laninamivir and peramivir

Influenza is an important cause of annual epidemics of respiratory viral infection associated with significant morbidity and mortality. Three classes of drugs, the M2 ion channel, neuraminidase and RNA-dependent RNA polymerase inhibitors, are approved for the prevention and treatment of influenza. Due to widespread resistance to the class, the M2 ion channel inhibitors are not recommended currently for therapy. The only polymerase inhibitor, favipiravir, is approved only in Japan and its use is highly restricted. Despite significant data to support the early use of the neuraminidase inhibitors, their use in all patient populations is suboptimal. The data to support the early use of neuraminidase inhibitors will be reviewed, as will current data on the utilization rates in ambulatory and hospitalized populations.

Topics: Acids, Carbocyclic; Antiviral Agents; Cyclopentanes; Drug Resistance, Viral; Enzyme Inhibitors; Guanidines; Humans; Influenza A virus; Influenza, Human; Neuraminidase; Oseltamivir; Pyrans; RNA-Dependent RNA Polymerase; Sialic Acids; Viral Matrix Proteins; Viral Proteins; Zanamivir

Influenza is a major cause of substantial morbidity and mortality in humans every year. Vaccination is the main strategy to prevent influenza infection, but antiviral agents also play an important role in the control of both seasonal and pandemic influenza. During the influenza A/H1N1 pandemic in 2009, early prompt antiviral therapy may have reduced the severity of the influenza outcomes including pneumonia, hospitalization and mortality in the Republic of Korea. Since the 2009 H1N1 pandemic, there have been increasing usages of antiviral agents for the treatment of patients with seasonal influenza. Although currently rare, antiviral resistance among influenza viruses may emerge and increase with increased use of neuraminidase inhibitors. New agents with different modes of action are under investigation, including favipiravir, DAS181, nitazoxanide and broad-spectrum neutralizing monoclonal antibodies. Data are limited with respect to high-dose and combination antiviral therapies. So, clinical trials are warranted to evaluate diverse antiviral combinations that may be synergistic and less likely to induce breakthrough resistance.

Topics: Acids, Carbocyclic; Amides; Antiviral Agents; Clinical Trials as Topic; Cyclopentanes; Drug Resistance, Viral; Guanidines; Hospitalization; Humans; Influenza A Virus, H1N1 Subtype; Influenza, Human; Oseltamivir; Pyrans; Pyrazines; Republic of Korea; Sialic Acids; Zanamivir

Topics: Acids, Carbocyclic; Amantadine; Antiviral Agents; Cyclopentanes; Drug Resistance, Viral; Guanidines; Humans; Influenza A virus; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Viral Matrix Proteins; Zanamivir

Human infections with avian influenza A (H5N1) are relatively rare but are associated with high mortality. As of July 5, 2010 there had been 500 cases and 296 fatalities. The influenza virus readily undergoes mutation and reassortment, and there are concerns that an H5N1 variant could be responsible for a future pandemic. The influenza neuraminidase inhibitors zanamivir and oseltamivir are approved for the treatment and prophylaxis of influenza. Oseltamivir is being used to treat H5N1 infections and the case has been made for a role for zanamivir; however, there are no case reports for the latter. Zanamivir is a potent inhibitor of H5N1, attains high lung concentrations immediately on administration, distributes into plasma at antiviral concentrations, has a low propensity for generating resistant virus, and retains activity against H275Y oseltamivir-resistant virus. There have been several reports of oseltamivir-resistant H5N1 arising during treatment with oseltamivir, and zanamivir retains effectiveness (in vitro or in vivo) against these isolates. Compassionate use of intravenous zanamivir for the treatment of seriously ill patients, including those with H275Y H1N1 infections, has also shown promising results. It is concluded that there is a role for zanamivir in treating H5N1 infections either as the approved, inhaled formulation in patients capable of using the Diskhaler, or as the intravenous formulation if compassionate use is warranted. The relatively small number of patients with these infections remains an obstacle to completion of clinical trials. Evidence is therefore likely to be based on carefully documented case reports, ideally in patients treated early in the course of the infection.

Topics: Acids, Carbocyclic; Antiviral Agents; Cyclopentanes; Disease Outbreaks; Drug Resistance, Viral; Guanidines; Humans; Immunocompromised Host; Influenza A Virus, H5N1 Subtype; Influenza, Human; Oseltamivir; Pneumonia, Viral; Pyrans; Severity of Illness Index; Sialic Acids; Zanamivir

Neuraminidase inhibitors (NAIs) reduce influenza symptoms but clear evidence of relationships between viral titer reduction and symptom alleviation is lacking. This open-label, randomized study evaluated differences in viral dynamics between NAIs, and relationships between viral dynamics and influenza symptoms (trial registration number: UMIN000012670).. Patients (n = 123) aged 4-12 years with influenza A virus infection were randomized to intravenous peramivir, oral oseltamivir, inhaled zanamivir, or inhaled laninamivir. Patients received regular viral assessments of nasal discharge, at least until rapid antigen tests were negative. Time to virus clearance, based on influenza virus titer, was the primary endpoint.. Peramivir recipients had a significantly shorter time to virus clearance than oseltamivir recipients (adjusted p = 0.035). Comparisons between the peramivir group and other NAI groups were not significant. There were no significant inter-group differences in other clinical efficacy endpoints (time to resolution of fever, time to alleviation of symptoms). However, the peramivir group showed a smaller numerical proportion of relapses with fever or positive virus than the other groups.. The time to virus clearance was significantly shorter with peramivir than with oseltamivir. Although no clear relationship between virus dynamics and symptoms was observed, ongoing studies should clarify the situation.

Topics: Acids, Carbocyclic; Antiviral Agents; Child; Child, Preschool; Cyclopentanes; Female; Guanidines; Humans; Influenza A virus; Influenza, Human; Japan; Male; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Time Factors; Treatment Outcome; Zanamivir

Topics: Acids, Carbocyclic; Adult; Antiviral Agents; Cyclopentanes; Female; Guanidines; Humans; Influenza, Human; Japan; Male; Middle Aged; Oseltamivir; Pyrans; Sialic Acids; Treatment Outcome; Zanamivir

The neuraminidase inhibitors (NAIs) oseltamivir, zanamivir, laninamivir and peramivir are available in Japan. However, the selective use of NAIs for treating outpatients with influenza has not been clearly defined.. We assigned 191 patients with influenza to 4 groups, each treated with a different NAI, and then compared how long it took to alleviate fever and other symptoms and to eliminate the virus.. Alleviation of fever occurred significantly sooner with peramivir than with either zanamivir (p = 0.0002) or oseltamivir (p = 0.0059), but was not significantly different from that with laninamivir (p = 0.0457; p < 0.0083). Other symptoms were also alleviated sooner by peramivir than by the other 3 NAIs.. The ability of each NAI to alleviate influenza symptoms and fever varied. The appropriate use of NAIs requires further study.

Topics: Acids, Carbocyclic; Adult; Aged; Aged, 80 and over; Antiviral Agents; Child; Child, Preschool; Cyclopentanes; Enzyme Inhibitors; Female; Guanidines; Humans; Infant; Influenza, Human; Japan; Male; Middle Aged; Neuraminidase; Oseltamivir; Outpatients; Pyrans; Sialic Acids; Time Factors; Treatment Outcome; Young Adult; Zanamivir

We aimed to investigate the association between anaphylaxis and anti-influenza drug use using the Japanese Adverse Drug Event Report (JADER) database, a national spontaneous reporting database in Japan. We surveyed registered cases from the JADER database between April 2004 and November 2019. The target drugs were five anti-influenza drugs, namely oseltamivir, zanamivir, peramivir, laninamivir, and baloxavir. Adverse events associated with anaphylaxis, "anaphylactic reaction," "anaphylactic shock," "anaphylactoid reaction," and "anaphylactoid shock," were evaluated. The association between anaphylaxis and anti-influenza drug use was assessed by calculating the reporting odds ratio (ROR) and information component (IC) as a measure of disproportionality. Signals were considered positive if the lower limit of the 95% confidence interval (CI) of ROR was > 1, and that of IC was > 0. The number of anaphylaxis cases associated with anti-influenza drug use was 199 (0.9%). Signals were detected for inhaled laninamivir (ROR: 4.24 [95% CI: 3.06-5.88], IC: 1.83 [1.35-2.30]), intravenous peramivir (ROR: 2.97 [2.11-4.17], IC: 1.40 [0.90-1.89]), and oral baloxavir (ROR: 3.05 [2.22-4.18], IC: 1.44 [0.98-1.90]). Conversely, signals were not detected for oral oseltamivir or inhaled zanamivir. Although zanamivir and laninamivir were used as dry powder inhalers containing lactose as an additive, they differed in terms of signal detection. Our analysis indicated that the signal of anaphylaxis may varies based on the main component or dosage form of each anti-influenza drug. Appropriate use of these drugs is essential to prevent anaphylaxis and improve health status.

Topics: Acids, Carbocyclic; Adult; Adverse Drug Reaction Reporting Systems; Anaphylaxis; Antiviral Agents; Databases, Factual; Dibenzothiepins; Female; Guanidines; Humans; Influenza, Human; Japan; Male; Middle Aged; Morpholines; Pyrans; Pyridones; Sialic Acids; Triazines; Young Adult

The recommended antiviral drugs available for the treatment and prevention of influenza are neuraminidase inhibitors (NAIs). The aim of this study was to evaluate age-related clinical manifestations of adverse events (AEs) related to NAIs. FAERS and WebMD data were downloaded. The available NAIs selected for the analysis were oseltamivir, peramivir, zanamivir, and laninamivir. Disproportionality was analyzed using the proportional reporting ratio (PRR), the reporting odds ratio (ROR), and the information component (IC) methods. In total, 16729 AEs from 4598 patients and 575 AEs from 440 patients in the FAERS and WebMD, respectively, were included in the analysis. In the FAERS, AEs were more common among those who were younger (<19 years) for zanamivir, while for those who were older (>65 years) for peramivir. A disproportionality analysis showed that signals for vomiting and hallucinations were detected in younger patients given oseltamivir, while an abnormal hepatic function, cardiac failure, shock, and cardio-respiratory arrest were detected in older patients given peramivir. Psychiatric disorders were most common in younger and older patients, while gastrointestinal disorders were most common in adult given oseltamivir in the WebMD. Adverse symptoms related to NAIs varied and depended on the drugs used and the age of the patient.

Topics: Acids, Carbocyclic; Adolescent; Adult; Adverse Drug Reaction Reporting Systems; Aged; Aged, 80 and over; Antiviral Agents; Child; Child, Preschool; Female; Guanidines; Humans; Infant; Infant, Newborn; Influenza, Human; Internet; Male; Middle Aged; Neuraminidase; Odds Ratio; Oseltamivir; Patient Participation; Pyrans; Risk Factors; Sialic Acids; United States; United States Food and Drug Administration; Young Adult; Zanamivir

Our earlier study investigated the incidence of severe abnormal behavior associated with neuraminidase inhibitors (NIs), but some studies have specifically examined the association of oseltamivir use and moderately abnormal behavior. Therefore, this study was undertaken to assess associations between moderately abnormal behavior and administered drugs. All cases of patients with influenza who exhibited moderately abnormal behavior were reported to us by physicians of all sentinel clinics and hospitals for influenza throughout Japan. Open Data of the National Database of Electronic Medical Claims include the numbers of patients diagnosed as having influenza who were prescribed NI. Incidence by NI was tested using Fisher's exact test. We received 518 moderately abnormal cases in 5-9-year-olds and 207 moderately abnormal behavior cases in 10-19-year-olds. The incidence among NI ranged from 193 per one million influenza patients in laninamivir among 10-19-year-olds to 1021 for peramivir among 5-9-year-olds. Estimation results revealed the order of risk among NIs as peramivir, oseltamivir, zanamivir and laninamivir in moderate abnormal behavior. Because of data limitations, risk among patients with and without NI cannot be compared.

Topics: Acids, Carbocyclic; Adolescent; Antiviral Agents; Child; Cyclopentanes; Enzyme Inhibitors; Guanidines; Humans; Illness Behavior; Influenza, Human; Japan; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Young Adult; Zanamivir

Topics: Acids, Carbocyclic; Adult; Antiviral Agents; Dibenzothiepins; Drug Resistance, Viral; Guanidines; Humans; Indonesia; Influenza B virus; Influenza, Human; Japan; Male; Microbial Sensitivity Tests; Morpholines; Mutation; Neuraminidase; Pyrans; Pyridones; Sialic Acids; Triazines; Zanamivir

Avian A(H7N9) infections in humans have been reported in China since 2013 and are of public health concern due to their severity and pandemic potential. Oseltamivir and peramivir are neuraminidase inhibitors (NAIs) routinely used for the treatment of A(H7N9) infections, but variants with reduced sensitivity to these drugs can emerge in patients during treatment. Zanamivir and laninamivir are NAIs that are used less frequently. Herein, we performed in vitro serial passaging experiments with recombinant viruses, containing the neuraminidase (NA) from influenza A/Anhui/1/13 (H7N9) virus, in the presence of each NAI, to determine whether variants with reduced sensitivity would emerge. NA substitutions were characterized for their effect on the NA enzymatic activity and surface expression of the A/Anhui/1/13 (Anhui/1) NA, as well as NAs originating from contemporary A(H7N9) viruses of the Yangtze River Delta and Pearl River Delta lineages. In vitro passage in the presence of oseltamivir, peramivir and laninamivir selected for substitutions associated with reduced sensitivity (E119D, R292K and R152K), whereas passage in the presence of zanamivir did not select for any viruses with reduced sensitivity. All the NA substitutions significantly reduced activity, but not the expression of the Anhui/1 NA. In contemporary N9 NAs, all substitutions tested significantly reduced NA enzyme function in the Yangtze River lineage background, but not in the Pearl River Delta lineage background. Overall, these findings suggest that zanamivir may be less likely than the other NAIs to select for resistance in A(H7N9) viruses and that the impact of substitutions that reduce NAI susceptibility or enzyme function may be less in A(H7N9) viruses from the Pearl River lineage.

Topics: Acids, Carbocyclic; Amino Acid Substitution; Animals; Antiviral Agents; Cyclopentanes; Dogs; Drug Resistance, Viral; Enzyme Inhibitors; Guanidines; HEK293 Cells; Humans; Influenza A Virus, H7N9 Subtype; Madin Darby Canine Kidney Cells; Neuraminidase; Oseltamivir; Pyrans; Serial Passage; Sialic Acids; Species Specificity; Viral Proteins; Zanamivir

The clinical effectiveness of four neuraminidase inhibitors (NAIs) (oseltamivir, zanamivir, laninamivir, and peramivir) for children aged 0 months to 18 years with influenza A and B were investigated in the 2014-2015 to 2016-2017 influenza seasons in Japan. A total of 1207 patients (747 with influenza A and 460 with influenza B) were enrolled. The Cox proportional-hazards model using all of the patients showed that the duration of fever after administration of the first dose of the NAI was shorter in older patients (hazard ratio = 1.06 per 1 year of age, p < 0.001) and that the duration of fever after administration of the first dose of the NAI was shorter in patients with influenza A infection than in patients with influenza B infection (hazard ratio = 2.21, p < 0.001). A logistic regression model showed that the number of biphasic fever episodes was 2.99-times greater for influenza B-infected patients than for influenza A-infected patients (p < 0.001). The number of biphasic fever episodes in influenza A- or B-infected patients aged 0-4 years was 2.89-times greater than that in patients aged 10-18 years (p = 0.010), and the number of episodes in influenza A- or B-infected patients aged 5-9 years was 2.13-times greater than that in patients aged 10-18 years (p = 0.012).

Topics: Acids, Carbocyclic; Adolescent; Betainfluenzavirus; Child; Child, Preschool; Cyclopentanes; Enzyme Inhibitors; Female; Guanidines; Humans; Infant; Infant, Newborn; Influenza A virus; Influenza, Human; Japan; Male; Neuraminidase; Oseltamivir; Pyrans; Seasons; Sialic Acids; Treatment Outcome; Zanamivir

Neuraminidase inhibitors are recommended for children hospitalized with influenza-related respiratory infections, and oseltamivir is the first choice of treatment in most situations. However, little is known regarding the recent trend in using neuraminidase inhibitors and their difference in health economy. The aim of this study was to reveal recent trends in neuraminidase inhibitor use and compare hospitalization costs across different treatment regimens.. We retrospectively obtained the hospital discharge records of inpatients under 18 years of age with a diagnosis of influenza-related respiratory infections using a national inpatient database in Japan. We excluded patients with chronic medical conditions from the analyses. Multivariable mixed effects regression models were used to investigate the recent treatment trends and healthcare costs.. We identified 27 771 inpatients with influenza-related respiratory infections. The proportions of neuraminidase inhibitor use increased from 62.6% in 2010 to 71.8% in2014 (P. We observed an increasing trend in peramivir use and decreasing trends in use of oseltamivir and zanamivir. Treatment with peramivir required higher hospitalization costs.

Topics: Acids, Carbocyclic; Antiviral Agents; Child; Child, Preschool; Cyclopentanes; Drug Utilization; Enzyme Inhibitors; Female; Guanidines; Hospitalization; Humans; Infant; Influenza, Human; Japan; Male; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Zanamivir

Topics: Acids, Carbocyclic; Amino Acid Substitution; Antiviral Agents; Cyclopentanes; Drug Resistance, Viral; Enzyme Inhibitors; Epidemiological Monitoring; Global Health; Guanidines; Humans; Influenza A Virus, H1N1 Subtype; Influenza B virus; Influenza, Human; Inhibitory Concentration 50; Microbial Sensitivity Tests; Neuraminidase; Oseltamivir; Pyrans; Seasons; Sialic Acids; World Health Organization; Zanamivir

Neuraminidase (NA) inhibitors are the recommended antiviral medications for influenza treatment. However, their therapeutic efficacy can be compromised by NA changes that emerge naturally and/or following antiviral treatment. Knowledge of which molecular changes confer drug resistance of influenza A(H7N9) viruses (group 2NA) remains sparse.. Fourteen amino acid substitutions were introduced into the NA of A/Shanghai/2/2013(H7N9). Recombinant N9 (recN9) proteins were expressed in a baculovirus system in insect cells and tested using the Centers for Disease Control and Prevention standardized NA inhibition (NI) assay with oseltamivir, zanamivir, peramivir, and laninamivir. The wild-type N9 crystal structure was determined in complex with oseltamivir, zanamivir, or sialic acid, and structural analysis was performed.. All substitutions conferred either reduced or highly reduced inhibition by at least 1 NA inhibitor; half of them caused reduced inhibition or highly reduced inhibition by all NA inhibitors. R292K conferred the highest increase in oseltamivir half-maximal inhibitory concentration (IC50), and E119D conferred the highest zanamivir IC50. Unlike N2 (another group 2NA), H274Y conferred highly reduced inhibition by oseltamivir. Additionally, R152K, a naturally occurring variation at the NA catalytic residue of A(H7N9) viruses, conferred reduced inhibition by laninamivir.. The recNA method is a valuable tool for assessing the effect of NA changes on drug susceptibility of emerging influenza viruses.

Topics: Acids, Carbocyclic; Antiviral Agents; Cyclopentanes; Databases, Genetic; Drug Resistance, Multiple, Viral; Enzyme Inhibitors; Guanidines; Humans; Influenza A Virus, H7N9 Subtype; Influenza, Human; Inhibitory Concentration 50; Neuraminidase; Oseltamivir; Protein Conformation; Pyrans; Recombinant Proteins; Sialic Acids; Viral Proteins; Zanamivir

We evaluated the environmental fate of new three anti-influenza drugs, favipiravir (FAV), peramivir (PER), and laninamivir (LAN), and an active prodrug of LAN, laninamivir octanoate (LANO), in comparison with four conventional drugs, oseltamivir (OS), oseltamivir carboxylate (OC), amantadine (AMN), and zanamivir (ZAN) by photodegradation, biodegradation, and sorption to river sediments. In addition, we conducted 9-month survey of urban rivers in the Yodo River basin from 2015 to 2016 (including the influenza season) to investigate the current status of occurrence of these drugs in the river environment. The results clearly showed that FAV and LAN rapidly disappeared through photodegradation (half-lives 1 and 8 h, respectively), followed by LANO which gradually disappeared through biodegradation (half-life, 2 days). The remained PER and conventional drugs were, however, persistent and transported from upstream to downstream sites. Rates of their sorption to river sediments were negligibly small. Detected levels remained were in the range from N.D. to 89 ng/L for the river waters and from N.D. to 906 ng/L in sewage effluent. However, all of the remained drugs were effectively removed by ozonation after chlorination at a sewage treatment plant. These findings suggest the importance of introducing ozonation for reduction of pollution loads in rivers, helping to keep river environments safe. To the best of our knowledge, this is the first evaluation of the removal effects of natural sunlight, biodegradation, and sorption to river sediments on FAV, PER, LAN, LANO, and a conventional drug, AMN.

Topics: Acids, Carbocyclic; Amides; Antiviral Agents; Biodegradation, Environmental; Cyclopentanes; Environmental Monitoring; Fresh Water; Guanidines; Half-Life; Humans; Influenza, Human; Japan; Prodrugs; Pyrans; Pyrazines; Rivers; Seasons; Sewage; Sialic Acids; Water Pollutants, Chemical; Zanamivir

Background In Japan, four neuraminidase inhibitors (NAIs) are currently prescribed to patients with influenza A and B. To know the backgrounds and clinical courses of patients with influenza who were treated with NAIs is important in the selection of appropriate medications. Methods We conducted a multicenter observational study in Osaka with postcard questionnaires. Patients who were prescribed NAIs were provided postcard questionnaires containing questions on their backgrounds, body temperatures, and durations of other influenza symptoms. We analyzed the factors that were associated with early fever alleviation using a logistic regression model. Results The postcard response rate was 31% (326 of 1050), and 307 patients were enrolled in this study [150 patients who were under 10 years old (type A, 118; and type B, 32) and 157 patients who were 10 or older (type A, 114; and type B, 43)]. In the patients under 10, the multivariate analysis showed that influenza type (Type B vs Type A; Odds Ratio, 0.13; 95% Confidence Interval: 0.04-0.38) was associated with early fever alleviation. However, NAIs were not related to early fever alleviation. Laninamivir tended to contribute more to early fever alleviation compared to oseltamivir in patients under 10 (Odds Ratio, 2.50;$95% Confidence Interval: 0.90-7.80). Conclusions The types,of prescibed NAIs were not significantly related to early fever alleviation. However, the fever durations of the patients under 10 who were prescribed laninamivir were shorter than those of patients under 10 who were prescribed oseltamivir or zanamivir.

Topics: Acids, Carbocyclic; Adolescent; Adult; Aged; Aged, 80 and over; Antiviral Agents; Child; Child, Preschool; Cyclopentanes; Disease Outbreaks; Enzyme Inhibitors; Female; Guanidines; Humans; Infant; Influenza, Human; Japan; Male; Middle Aged; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Surveys and Questionnaires; Treatment Outcome; Zanamivir

Oseltamivir and Zanamivir are two of the recently licensed neuraminidase inhibitors used for the treatment of influenza. However, alternative antiviral agents are needed due to the development of resistant mutations in Oseltamivir subtype H1N1 and H5N1 avian influenza A viruses, the latter being a highly pathogenic avian virus that can be transferred to humans upon immediate contact with H5N1 infected poultry or surface. Novel drug inhibiting group 1 neuraminidases may potentially be developed through addition of extra substituent moieties to existing inhibitor skeletons. Another approach involves virtual screening of existing inhibitor skeletons which we have reported using novel ligands of H5N1 via virtual screening approach. In this study, we have used 3D structure of avian influenza virus H5N1 neuraminidase as target against a ligand dataset of four known neuraminidase inhibitors for in silico analysis. Using the dataset of known four inhibitors, a pharmacophore model was developed using ligand-based pharmacophore modeling strategy. This pharmacophore model was then used for virtual screening of natural compounds library taken from Princeton database. New hits that shared features of our pharmacophore model and binding interactions with receptor residues have been reported in this study. As more antiviral agents are required, the reported hits in our study may play an important role as novel antiviral agents against influenza virus.

Topics: Acids, Carbocyclic; Binding Sites; Cyclopentanes; Databases, Chemical; Glycoside Hydrolase Inhibitors; Guanidines; Influenza A Virus, H5N1 Subtype; Ligands; Molecular Docking Simulation; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Structure-Activity Relationship; Viral Proteins; Zanamivir

Shedding of the pandemic virus during an influenza pandemic is thought to persist longer than shedding of influenza viruses during annual influenza seasons, because people have much less immunity against a pandemic influenza. A correlation is thought to exist between the length of virus shedding and the clinical severity of influenza illness.. We compared the virus isolation rates of children with pandemic A H1N1/09 influenza infection and children with A H3N2 influenza infection after the patients had been treated with one of three neuraminidase inhibitors (NAI) such as peramivir, laninamivir and oseltamivir. The clinical effectiveness of each NAI was assessed on the basis of the duration of the febrile period after the start of treatment.. Influenza viruses were isolated from 15 of the 34 patients in the A H3N2 group (mean age 6.2 years) and from 4 of the 25 patients in the A H1N1/09 (mean age 5.6 years) virus group (44.1% versus 16.0%; P<0.05). However, the differences between the duration of fever in the patients in the A H3N2 group and A H1N1/09 group after treatment with the NAIs were not significant.. The virus isolation rates after treatment with each of the NAIs were significantly lower in the A H1N1/09 group, suggesting that the pandemic A H1N1/09 virus was more sensitive to the NAIs than the seasonal A H3N2 virus was. Clinically, there were no significant differences in the effectiveness of the NAIs between the H1N1/09 infected group and H3N2 infected group.

Topics: Acids, Carbocyclic; Antiviral Agents; Child; Child, Preschool; Cyclopentanes; Enzyme Inhibitors; Female; Fever; Guanidines; Humans; Infant; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Influenza, Human; Male; Neuraminidase; Oseltamivir; Pyrans; Severity of Illness Index; Sialic Acids; Time Factors; Treatment Outcome; Viral Proteins; Virus Shedding; Zanamivir

Four World Health Organization (WHO) Collaborating Centres for Reference and Research on Influenza and one WHO Collaborating Centre for the Surveillance, Epidemiology and Control of Influenza (WHO CCs) tested 10,641 viruses collected by WHO-recognized National Influenza Centres between May 2013 and May 2014 to determine 50% inhibitory concentration (IC50) data for neuraminidase inhibitors (NAIs) oseltamivir, zanamivir, peramivir and laninamivir. In addition, neuraminidase (NA) sequence data, available from the WHO CCs and from sequence databases (n=3206), were screened for amino acid substitutions associated with reduced NAI susceptibility. Ninety-five per cent of the viruses tested by the WHO CCs were from three WHO regions: Western Pacific, the Americas and Europe. Approximately 2% (n=172) showed highly reduced inhibition (HRI) against at least one of the four NAIs, commonly oseltamivir, while 0.3% (n=32) showed reduced inhibition (RI). Those showing HRI were A(H1N1)pdm09 with NA H275Y (n=169), A(H3N2) with NA E119V (n=1), B/Victoria-lineage with NA E117G (n=1) and B/Yamagata-lineage with NA H273Y (n=1); amino acid position numbering is A subtype and B type specific. Although approximately 98% of circulating viruses tested during the 2013-2014 period were sensitive to all four NAIs, a large community cluster of A(H1N1)pdm09 viruses with the NA H275Y substitution from patients with no previous exposure to antivirals was detected in Hokkaido, Japan. Significant numbers of A(H1N1)pdm09 NA H275Y viruses were also detected in China and the United States: phylogenetic analyses showed that the Chinese viruses were similar to those from Japan, while the United States viruses clustered separately from those of the Hokkaido outbreak, indicative of multiple resistance-emergence events. Consequently, global surveillance of influenza antiviral susceptibility should be continued from a public health perspective.

Topics: Acids, Carbocyclic; Amino Acid Substitution; Antiviral Agents; China; Cyclopentanes; Disease Outbreaks; Drug Resistance, Viral; Enzyme Inhibitors; Europe; Guanidines; Humans; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Influenza B virus; Inhibitory Concentration 50; Japan; Microbial Sensitivity Tests; Neuraminidase; Oseltamivir; Phylogeny; Pyrans; Sialic Acids; Time Factors; United States; World Health Organization; Zanamivir

Prolonged treatment of an immunocompromised child with oseltamivir and zanamivir for A(H1N1)pdm09 virus infection led to the emergence of viruses carrying H275Y and/or E119G in the neuraminidase (NA). When phenotypically evaluated by NA inhibition, the dual H275Y-E119G substitution caused highly reduced inhibition by 4 NA inhibitors: oseltamivir, zanamivir, peramivir, and laninamivir.

Topics: Acids, Carbocyclic; Amino Acid Substitution; Antiviral Agents; Cyclopentanes; Drug Resistance, Viral; Enzyme Inhibitors; Guanidines; Humans; Immunocompromised Host; Infant; Influenza A Virus, H1N1 Subtype; Influenza, Human; Male; Mutation, Missense; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Viral Proteins; Zanamivir

To assess the extent of viral resistance, we measured the 50% inhibitory concentration (IC50) of neuraminidase inhibitors (NAIs) for the influenza virus isolates in the 2013-2014 influenza season and compared the results to those of the 2010-2011 to 2012-2013 influenza seasons. Viral isolation was done with specimens obtained prior to treatment, and the type and subtype of influenza was determined by RT-PCR using type- and subtype-specific primers. The IC50 was determined by a neuraminidase inhibition assay using a fluorescent substrate. A total of 327 influenza viruses were isolated: 172 influenza A(H1N1)pdm09 (52.6%), 49 A(H3N2) (15.0%), and 106 B (32.4%). Numbers of Victoria and Yamagata lineage isolates were 36 and 70, respectively. Two A(H1N1)pdm09 isolates showed a high IC50 for oseltamivir (130 and 150 nM) exceeding by 100 times the geometric mean of the IC50 of oseltamivir for A(H1N1)pdm09 isolates (0.76 nM). No isolate showed a very high IC50 for A(H3N2) or B. The IC50 of the NAIs except for oseltamivir for A(H1N1) pdm09 were significantly higher than those of the 2010-2011 season (P < 0.05). The IC50 of all four NAIs for A(H3N2) were significantly lower than those of the 2012-2013 season (P < 0.001). The IC50 of the NAIs for B except for oseltamivir were significantly lower than those of the 2012-2013 season (P < 0.001). Although there are some isolates that show highly reduced sensitivity to oseltamivir among A(H1N1)pdm09 isolates, the currently epidemic influenza A(H1N1)pdm09, A(H3N2) and B viruses are susceptible to all four NAIs with no trend toward decreased sensitivity.

Topics: Acids, Carbocyclic; Adolescent; Adult; Aged; Aged, 80 and over; Child; Child, Preschool; Cyclopentanes; Enzyme Inhibitors; Female; Guanidines; Humans; Infant; Infant, Newborn; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Influenza B virus; Influenza, Human; Inhibitory Concentration 50; Japan; Male; Middle Aged; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Time Factors; Young Adult; Zanamivir

This is the first report of the detection of two new anti-influenza drugs, peramivir (PER) and laninamivir (LAN), in Japanese sewage effluent and river waters. Over about 1 year from October 2013 to July 2014, including the influenza prevalence season in January and February 2014, we monitored for five anti-influenza drugs-oseltamivir (OS), oseltamivir carboxylate (OC), zanamivir (ZAN), PER, and LAN-in river waters and in sewage effluent flowing into urban rivers of the Yodo River system in Japan. The dynamic profiles of these anti-influenza drugs were synchronized well with that of the numbers of influenza patients treated with the drugs. The highest levels in sewage effluents and river waters were, respectively, 82 and 41 ng/L (OS), 347 and 125 ng/L (OC), 110 and 35 ng/L (ZAN), 64 and 11 ng/L (PER), and 21 and 9 ng/L (LAN). However, application of ozone treatment before discharge from sewage treatment plants was effective in reducing the levels of these anti-influenza drugs in effluent. The effectiveness of the ozone treatment and the drug dependent difference in susceptibility against ozone were further evidenced by ozonation of a STP effluent in a batch reactor. These findings should help to promote further environmental risk assessment of the generation of drug-resistant influenza viruses in aquatic environments.

Topics: Acids, Carbocyclic; Antiviral Agents; Cities; Cyclopentanes; Drug Residues; Environmental Monitoring; Guanidines; Japan; Limit of Detection; Oseltamivir; Ozone; Pyrans; Risk Assessment; Rivers; Sewage; Sialic Acids; Water Pollutants, Chemical; Water Purification; Zanamivir

Since 2011, outbreaks caused by influenza A(H3N2) variant [A(H3N2)v] viruses have become a public health concern in the United States. The A(H3N2)v viruses share the A(H1N1)pdm09 M gene containing the marker of M2 blocker resistance, S31N, but do not contain any known molecular markers associated with resistance to neuraminidase (NA) inhibitors (NAIs). Using a fluorescent NA inhibition (NI) assay, the susceptibilities of recovered A(H3N2)v viruses (n=168) to FDA-approved (oseltamivir and zanamivir) and other (peramivir, laninamivir, and A-315675) NAIs were assessed. All A(H3N2)v viruses tested, with the exception of a single virus strain, A/Ohio/88/2012, isolated from an untreated patient, were susceptible to the NAIs tested. The A/Ohio/88/2012 virus contained two rare substitutions, S245N and S247P, in the NA and demonstrated reduced inhibition by oseltamivir (31-fold) and zanamivir (66-fold) in the NI assay. Using recombinant NA (recNA) proteins, S247P was shown to be responsible for the observed altered NAI susceptibility, in addition to an approximately 60% reduction in NA enzymatic activity. The S247P substitution has not been previously reported as a molecular marker of reduced susceptibility to the NAIs. Using cell culture assays, the investigational antiviral drugs nitazoxanide, favipiravir, and fludase were shown to inhibit the replication of A(H3N2)v viruses, including the virus with the S247P substitution in the NA. This report demonstrates the importance of continuous monitoring of susceptibility of zoonotic influenza viruses to available and investigational antiviral drugs.

Topics: Acids, Carbocyclic; Animals; Antiviral Agents; Cyclopentanes; Dogs; Guanidines; Humans; Influenza A Virus, H3N2 Subtype; Madin Darby Canine Kidney Cells; Oseltamivir; Pyrans; Sialic Acids; United States; Virus Replication; Zanamivir

Influenza viruses collected from regions of Asia, Africa and Oceania between 2009 and 2012 were tested for their susceptibility to two new neuraminidase inhibitors, peramivir and laninamivir. All viruses tested had normal laninamivir inhibition. However, 3·2% (19/599) of A(H1N1)pdm09 viruses had highly reduced peramivir inhibition (due to H275Y NA mutation) and <1% (6/1238) of influenza B viruses had reduced or highly reduced peramivir inhibition, with single occurrence of variants containing I221T, A245T, K360E, A395E, D432G and a combined G145R+Y142H mutation. These data demonstrate that despite an increase in H275Y variants in 2011, there was no marked change in the frequency of peramivir- or laninamivir-resistant variants following the market release of the drugs in Japan in 2010.

Topics: Acids, Carbocyclic; Africa; Antiviral Agents; Asia; Cyclopentanes; Guanidines; Humans; Influenza A virus; Influenza B virus; Influenza, Human; Japan; Microbial Sensitivity Tests; Mutation, Missense; Neuraminidase; Oceania; Pyrans; Sialic Acids; Viral Proteins; Zanamivir

Emergence of influenza viruses with reduced susceptibility to neuraminidase inhibitors (NAIs) is sporadic, often follows exposure to NAIs, but occasionally occurs in the absence of NAI pressure. The emergence and global spread in 2007/2008 of A(H1N1) influenza viruses showing clinical resistance to oseltamivir due to neuraminidase (NA) H275Y substitution, in the absence of drug pressure, warrants continued vigilance and monitoring for similar viruses. Four World Health Organization (WHO) Collaborating Centres for Reference and Research on Influenza and one WHO Collaborating Centre for the Surveillance, Epidemiology and Control of Influenza (WHO CCs) tested 11,387 viruses collected by WHO-recognized National Influenza Centres (NIC) between May 2012 and May 2013 to determine 50% inhibitory concentration (IC50) data for oseltamivir, zanamivir, peramivir and laninamivir. The data were evaluated using normalized IC50 fold-changes rather than raw IC50 data. Nearly 90% of the 11,387 viruses were from three WHO regions: Western Pacific, the Americas and Europe. Only 0.2% (n=27) showed highly reduced inhibition (HRI) against at least one of the four NAIs, usually oseltamivir, while 0.3% (n=39) showed reduced inhibition (RI). NA sequence data, available from the WHO CCs and from sequence databases (n=3661), were screened for amino acid substitutions associated with reduced NAI susceptibility. Those showing HRI were A(H1N1)pdm09 with NA H275Y (n=18), A(H3N2) with NA E119V (n=3) or NA R292K (n=1) and B/Victoria-lineage with NA H273Y (n=2); amino acid position numbering is A subtype and B type specific. Overall, approximately 99% of circulating viruses tested during the 2012-2013 period were sensitive to all four NAIs. Consequently, these drugs remain an appropriate choice for the treatment and prophylaxis of influenza virus infections.

Topics: Acids, Carbocyclic; Amino Acid Substitution; Antiviral Agents; Cyclopentanes; Drug Resistance, Viral; Enzyme Inhibitors; Guanidines; Humans; Influenza A virus; Influenza, Human; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Zanamivir

To genetically characterize human influenza viruses and their susceptibilities to antivirals during two post-pandemic seasons in Lebanon.. Influenza virus was isolated from nasopharyngeal swabs that were obtained from patients with influenza-like illness during 2010-2012 and further analyzed both phenotypically and genotypically.. During the 2010-2011 season, both 2009 pandemic H1N1 (H1N1p) and B viruses co-circulated with equal prevalence, while the H3N2 virus predominated during the 2011-2012 season. All H3N2 and H1N1 viruses were resistant to amantadine. Importantly, all viruses of the influenza A and B types were susceptible to the neuraminidase (NA) inhibitors oseltamivir, zanamivir, peramivir, and laninamivir. Nonetheless, all 2011-2012 H1N1p isolates had three mutations (V241I, N369K, and N386S) in the NA gene that were suggested to be permissive of the H275Y mutation, which confers resistance to oseltamivir. We also detected one H1N1p virus during the 2010-2011 season with a 4-fold decrease in susceptibility to oseltamivir due to an NA-S247N mutation. This isolate was phylogenetically distinct from other H1N1p viruses that were isolated in other regions.. Influenza A viruses with reduced susceptibility to oseltamivir and mutations permissive for acquiring NA resistance-conferring mutation with minimal burden on their fitness were isolated in Lebanon.

Topics: Acids, Carbocyclic; Amantadine; Antiviral Agents; Cyclopentanes; Drug Resistance, Viral; Guanidines; Humans; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Influenza B virus; Influenza, Human; Lebanon; Microbial Sensitivity Tests; Mutation; Neuraminidase; Oseltamivir; Pandemics; Phylogeny; Pyrans; Sialic Acids; Zanamivir

Neuraminidase (NA) inhibitors (NAIs) are currently the only antivirals effective against influenza infections due to widespread resistance to M2 inhibitors.. Influenza A and B viruses (n = 1079) collected worldwide between April 01, 2011, and September 30, 2011, were assessed for susceptibility to FDA-approved NAIs, oseltamivir and zanamivir, and investigational peramivir, using the fluorescent-based NA-Fluor™ Influenza Neuraminidase Assay Kit. A subset of viruses (n = 98) were tested for susceptibility to the investigational NAI, laninamivir.. Influenza A(H1N1)pdm09 viruses (n = 326) were sensitive to all NAIs, except for two (0.6%) with H275Y (N1 numbering; H274Y in N2 numbering) substitution, which exhibited elevated IC50 s for oseltamivir and peramivir, and a third with previously unreported N325K substitution, exhibiting reduced susceptibility to oseltamivir. Influenza A(H3N2) viruses (n = 407) were sensitive to all NAIs. Influenza B viruses (n = 346) were sensitive to all NAIs, except two (0.6%) with H273Y (N1 numbering; H274Y in N2 numbering) substitution, exhibiting reduced susceptibility to oseltamivir and peramivir, and one with previously unreported G140R and N144K substitutions, exhibiting reduced susceptibility to oseltamivir, zanamivir, and peramivir. All influenza A and B viruses were sensitive to laninamivir. It is unknown whether substitutions N325K, G140R, and N144K were present in the virus prior to culturing because clinical specimens were unavailable for testing.. This study summarizes NAI susceptibility of influenza viruses circulating worldwide during the 2011 Southern Hemisphere (SH) season, assessed using the NA-Fluor™ Kit. Despite low resistance to NAIs among tested influenza viruses, constant surveillance of influenza virus susceptibility to NAIs should be emphasized.

Topics: Acids, Carbocyclic; Africa; Antiviral Agents; Cyclopentanes; Drug Resistance, Viral; Enzyme Inhibitors; Global Health; Guanidines; Humans; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Influenza B virus; Influenza, Human; Neuraminidase; Oceania; Oseltamivir; Pyrans; Seasons; Sentinel Surveillance; Sialic Acids; South America; Zanamivir

Two new influenza virus neuraminidase inhibitors (NAIs), peramivir and laninamivir, were approved in 2010 which resulted to four NAIs that were used during the 2010-2011 influenza season in Japan. This study aims to monitor the susceptibility of influenza virus isolates in 2009-2010 and 2010-2011 influenza seasons in Japan to the four NAIs using the fluorescence-based 50% inhibitory concentration (IC₅₀) method. Outliers were identified using box-and-whisker plot analysis and full NA gene sequencing was performed to determine the mutations that are associated with reduction of susceptibility to NAIs. A total of 117 influenza A(H1N1)pdm09, 59 A(H3N2), and 18 type B viruses were tested before NAI treatment and eight A(H1N1)pdm09 and 1 type B viruses were examined from patients after NAI treatment in the two seasons. NA inhibition assay showed type A influenza viruses were more susceptible to NAIs than type B viruses. The peramivir and laninamivir IC₅₀ values of both type A and B viruses were significantly lower than the oseltamivir and zanamivir IC₅₀ values. Among influenza A(H1N1)pdm09 viruses, the prevalence of H274Y viruses increased from 0% in the 2009-2010 season to 3% in the 2010-2011 season. These H274Y viruses were resistant to oseltamivir and peramivir with 200-300 fold increase in IC₅₀ values but remained sensitive to zanamivir and laninamivir. Other mutations in NA, such as I222T and M241I were identified among the outliers. Among influenza A(H3N2) viruses, two outliers were identified with D151G and T148I mutations, which exhibited a reduction in susceptibility to oseltamivir and zanamivir, respectively. Among type B viruses, no outliers were identified to the four NAIs. For paired samples that were collected before and after drug treatment, three (3/11; 27.3%) H274Y viruses were identified among A(H1N1)pdm09 viruses after oseltamivir treatment but no outliers were found in the laninamivir-treatment group (n=3). Despite widespread use of NAIs in Japan, the prevalence of NAI-resistant influenza viruses is still low.

Topics: Acids, Carbocyclic; Adult; Antiviral Agents; Cyclopentanes; Drug Resistance, Viral; Enzyme Inhibitors; Female; Guanidines; Humans; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Influenza B virus; Influenza, Human; Japan; Microbial Sensitivity Tests; Neuraminidase; Pandemics; Pyrans; Seasons; Sialic Acids; Viral Proteins; Zanamivir

Assessment of drug susceptibility has become an integral part of influenza virus surveillance. In this study, we describe the drug resistance profile of influenza A(H3N2) virus, A/Mississippi/05/2011, collected from a patient treated with oseltamivir and detected via surveillance. An MDCK cell-grown isolate of this virus exhibited highly reduced inhibition by the neuraminidase (NA) inhibitors (NAIs) oseltamivir (8,005-fold), zanamivir (813-fold), peramivir (116-fold), and laninamivir (257-fold) in the NA inhibition assay. Sequence analysis of its NA gene revealed a known oseltamivir-resistance marker, the glutamic acid-to-valine substitution at position 119 (E119V), and an additional change, threonine to isoleucine at position 148 (T148I). Unlike E119V, T148I was not detected in the clinical sample but acquired during viral propagation in MDCK cells. Using recombinant proteins, T148I by itself was shown to cause only a 6-fold increase in the zanamivir 50% inhibitory concentration (IC50) and had no effect on inhibition by other drugs. The T148I substitution reduced NA activity by 50%, most likely by affecting the positioning of the 150 loop at the NA catalytic site. Using pyrosequencing, changes at T148 were detected in 35 (23%) of 150 MDCK cell-grown A(H3N2) viruses tested, which was lower than the frequency of changes at D151 (85%), an NA residue previously implicated in cell selection. We demonstrate that culturing of the A(H3N2) viruses (n = 11) at a low multiplicity of infection delayed the emergence of the NA variants with changes at position 148 and/or 151, especially when conducted in MDCK-SIAT1 cells. Our findings highlight the current challenges in monitoring susceptibility of influenza A(H3N2) viruses to the NAI class of antiviral drugs.

Topics: Acids, Carbocyclic; Amino Acid Substitution; Animals; Antiviral Agents; Cell Culture Techniques; Cyclopentanes; Dogs; Drug Resistance, Viral; Enzyme Inhibitors; Gene Expression; Guanidines; Humans; Influenza A Virus, H3N2 Subtype; Inhibitory Concentration 50; Madin Darby Canine Kidney Cells; Neuraminidase; Oseltamivir; Pyrans; Sialic Acids; Viral Load; Viral Proteins; Virus Replication; Zanamivir

Drugs inhibiting the enzymatic activity of influenza virus neuraminidase (NA) are the cornerstone of therapy for influenza virus infection. The emergence of drug-resistant variants may limit the benefits of antiviral therapy. Here we report the recovery of an influenza B virus with reduced susceptibilities to NA inhibitors from a human patient with no history of antiviral drug treatment. The virus, designated B/Kochi/61/2011, was isolated by inoculating Madin-Darby canine kidney (MDCK) cells with respiratory specimens from the patient. NA inhibition assays demonstrated that the B/Kochi/61/2011 isolate showed a remarkable reduction in susceptibility to peramivir. The isolate also exhibited low to moderately reduced sensitivity to oseltamivir, laninamivir, and zanamivir. A sequence analysis of viruses propagated in MDCK cells revealed that the isolate contained a mutation (E105K) not previously associated with reduced susceptibility to NA inhibitors. However, pyrosequencing analysis showed that the NA E105K mutation was below a detectable level in the original clinical specimens, suggesting that the mutant virus may be preferably selected during propagation in MDCK cells. Analysis of the three-dimensional model of E105 and K105 NAs with peramivir suggested that the E105K mutation at the monomer-monomer interface of the NA tetramer may destabilize the tetrameric form of NA, leading to decreased susceptibility to NA inhibitors. These results have implications for understanding the mechanism of resistance against NA-inhibitor drugs.

Topics: Acids, Carbocyclic; Animals; Antiviral Agents; Catalytic Domain; Cyclopentanes; Dogs; Drug Resistance, Viral; Enzyme Inhibitors; Guanidines; HEK293 Cells; Humans; Influenza B virus; Madin Darby Canine Kidney Cells; Models, Molecular; Mutation; Neuraminidase; Oseltamivir; Protein Conformation; Pyrans; Sialic Acids; Viral Proteins; Zanamivir

The neuraminidase inhibitors (NAIs) zanamivir and oseltamivir are currently the only antiviral drugs effective for the treatment and prophylaxis of 2009 pandemic influenza A (H1N1) virus infections. The proven potential of these viruses to acquire NAI resistance during treatment emphasizes the need to assess their NAI susceptibility. The 50% inhibitory concentrations (IC(50)s) are known to vary depending on the neuraminidase inhibition (NI) test used; however, few side-by-side comparisons of different NI assays have been done. In the present study, a panel of 11 isolates representing 2009 seasonal and pandemic influenza H1N1 viruses, including oseltamivir-resistant H275Y variants, were tested in three functional NI assays: chemiluminescent (CL), fluorescent (FL), and colorimetric (CM). The sensitivities of the viruses to zanamivir, oseltamivir, and three investigational NAIs (peramivir, R-125489, and A-315675) were assessed. All isolates with the exception of H275Y variants were sensitive to all five NAIs by all three NI assays. The H275Y variants showed substantially elevated IC(50)s against oseltamivir and peramivir. The three NI assays generally yielded consistent results; thus, the choice of NI assay does not appear to affect conclusions based on drug susceptibility surveillance. Each assay, however, offers certain advantages compared to the others: the CL assay required less virus volume and the FL assay provided the greatest difference in the IC(50)s between the wild type and the variants, whereas the IC(50)s obtained from the CM assay may be the most predictive of the drug concentrations needed to inhibit enzyme activity in humans. It would be desirable to develop an NI assay which combines the advantages of all three currently available assays but which lacks their shortcomings.

Topics: Acids, Carbocyclic; Animals; Cell Line; Cyclopentanes; Dogs; Enzyme Assays; Enzyme Inhibitors; Guanidines; Humans; Influenza A Virus, H1N1 Subtype; Influenza, Human; Inhibitory Concentration 50; Neuraminidase; Oseltamivir; Zanamivir

Antiviral drugs are an important option for managing infections caused by influenza viruses. This study assessed the drug susceptibility of 2009 pandemic influenza A (H1N1) viruses collected globally between April 2009 and January 2010.. Virus isolates were tested for adamantane susceptibility, using pyrosequencing to detect the S31N marker of adamantane resistance in the M2 protein and biological assays to assess viral replication in cell culture. To assess neuraminidase (NA) inhibitor (NAI) susceptibility, virus isolates were tested in chemiluminescent NA inhibition assays and by pyrosequencing to detect the H275Y (H274Y in N2 numbering) marker of oseltamivir resistance in the NA.. With the exception of three, all viruses that were tested for adamantane susceptibility (n=3,362) were resistant to this class of drugs. All viruses tested for NAI susceptibility (n=3,359) were sensitive to two US Food and Drug Administration-approved NAIs, oseltamivir (mean ±sd 50% inhibitory concentration [IC(50)] 0.25 ±0.12 nM) and zanamivir (mean IC(50) 0.29 ±0.09 nM), except 23 (0.7%), which were resistant to oseltamivir, but sensitive to zanamivir. Oseltamivir-resistant viruses had the H275Y mutation in their NA and were detected in patients exposed to the drug through prophylaxis or treatment. NA activity of all viruses was inhibited by the NAIs peramivir, laninamivir (R-125489) and A-315675, except for H275Y variants, which exhibited approximately 100-fold reduction in peramivir susceptibility.. This report provides data regarding antiviral susceptibility of 2009 pandemic influenza A (H1N1) surveillance viruses, the majority of which were resistant to adamantanes and sensitive to NAIs. These findings provide information essential for antiviral resistance monitoring and development of novel diagnostic tests for detecting influenza antiviral resistance.

Topics: Acids, Carbocyclic; Adamantane; Amino Acid Substitution; Animals; Antiviral Agents; Cell Line; Cyclopentanes; Dogs; Drug Resistance, Viral; Enzyme Inhibitors; Guanidines; Humans; Influenza A Virus, H1N1 Subtype; Influenza, Human; Microbial Sensitivity Tests; Mutation, Missense; Neuraminidase; Oseltamivir; Pyrans; Pyrrolidines; Sialic Acids; Viral Plaque Assay; Zanamivir