zithromax and Poliomyelitis

Oral poliovirus vaccine is less immunogenic and effective in low-income countries than in high-income countries, similarly to other oral vaccines. The high prevalence of intestinal pathogens and associated environmental enteropathy has been proposed to explain this problem. Because administration of an antibiotic has the potential to resolve environmental enteropathy and clear bacterial pathogens, we aimed to assess whether antibiotics would improve oral poliovirus vaccine immunogenicity.. We did a double-blind, randomised, placebo-controlled trial of the effect of azithromycin on the immunogenicity of serotype-3 monovalent oral poliovirus vaccine given to healthy infants living in 14 blocks of Vellore district, India. Infants were eligible to participate if they were 6-11 months old, available for the study duration, and lacked serum neutralising antibodies to serotype-3 poliovirus. Infants were randomly assigned (1:1) at enrolment to receive oral 10 mg/kg azithromycin or placebo once daily for 3 days, followed by serotype-3 monovalent oral poliovirus vaccine on day 14. The primary outcome was detection of serum neutralising antibodies to serotype-3 poliovirus at a dilution of one in eight or more on day 35 and was assessed in the per-protocol population (ie, all those who received azithromycin or placebo, oral poliovirus vaccine, and provided a blood sample according to the study protocol). Safety outcomes were assessed in all infants enrolled in the study. The trial is registered with the Clinical Trials Registry India, number CTRI/2014/05/004588.. Between Aug 5, 2014, and March 21, 2015, 754 infants were randomly assigned: 376 to receive azithromycin and 378 to placebo. Of these, 348 (93%) of 376 in the azithromycin group and 357 (94%) of 378 infants in the placebo group completed the study per protocol. In the azithromycin group, 175 (50%) seroconverted to serotype-3 poliovirus compared with 192 (54%) in the placebo group (risk ratio 0·94, 95% CI 0·81-1·08; p=0·366). Azithromycin reduced faecal biomarkers of environmental enteropathy (calprotectin, myeloperoxidase, α1-antitrypsin) and the prevalence of bacterial but not viral or eukaryotic pathogens. Viral pathogens were associated with lower seroconversion. Three serious adverse events were reported (two in the azithromycin group and one in the placebo group), but none was considered related to the study interventions.. Azithromycin did not improve the immunogenicity of oral poliovirus vaccine despite reducing biomarkers of environmental enteropathy and the prevalence of pathogenic intestinal bacteria. Viral interference and innate antiviral immune mechanisms might be more important determinants of the immunogenicity of live-virus oral vaccines.. Bill & Melinda Gates Foundation.

Topics: Anti-Bacterial Agents; Antibodies, Viral; Azithromycin; Double-Blind Method; Humans; Immunization Schedule; Immunogenicity, Vaccine; India; Infant; Poliomyelitis; Poliovirus; Poliovirus Vaccine, Oral; Vaccination

Viral RNA-dependent RNA polymerase (RdRP) enzymes are essential for the replication of positive-strand RNA viruses and established targets for the development of selective antiviral therapeutics. In this work we have carried out a high-throughput screen of 154,267 compounds to identify poliovirus polymerase inhibitors using a fluorescence based RNA elongation assay. Screening and subsequent validation experiments using kinetic methods and RNA product analysis resulted in the identification of seven inhibitors that affect the RNA binding, initiation, or elongation activity of the polymerase. X-ray crystallography data show clear density for five of the compounds in the active site of the poliovirus polymerase elongation complex. The inhibitors occupy the NTP binding site by stacking on the priming nucleotide and interacting with the templating base, yet competition studies show fairly weak IC50 values in the low μM range. A comparison with nucleotide bound structures suggests that weak binding is likely due to the lack of a triphosphate group on the inhibitors. Consequently, the inhibitors are primarily effective at blocking polymerase initiation and do not effectively compete with NTP binding during processive elongation. These findings are discussed in the context of the polymerase elongation complex structure and allosteric control of the viral RdRP catalytic cycle.

Topics: Allosteric Regulation; Binding Sites; Catalytic Domain; Crystallography, X-Ray; Enzyme Inhibitors; Fluorescence; High-Throughput Screening Assays; Humans; Inhibitory Concentration 50; Models, Molecular; Nucleotides; Poliomyelitis; Poliovirus; Protein Binding; RNA-Dependent RNA Polymerase; RNA, Viral; Small Molecule Libraries; Virus Replication