sybr-green-i and Viremia

Quantification of titers of ubiquitous viruses such as Torque teno virus (TTV) that do not cause clinical symptoms might be helpful in assessing the immune status of an individual. We hereby describe the validation of a SYBR Green-based TTV quantification method for plasma samples.. Plasmids with TTV specific inserts were used for preparing standards and absolute quantification of TTV was performed using SYBR Green methodology. The method was assessed for its accuracy and precision (intra and inter-day) on four non-consecutive days. TTV was also quantified from plasma samples of 20 healthy volunteers and from 30 hematopoietic stem cell transplant (HSCT) recipients.. The assay was specific and showed satisfactory efficiency (82.2%, R2=0.99) with the limit of quantification defined as 100 copies per reaction. The assay had good precision (inter and intra-day coefficient of variation in cycle threshold (CT) < 4%) and accuracy (100 ± 10%) in the range of 100 to 1010 copies/reaction. We found TTV loads ranging from 2.5 - 4.07 log copies/mL of plasma with CT (mean ± SD) of 33.8 ± 1.77 in healthy individuals and 2.06 - 8.49 log copies/mL of plasma with CT (mean ± SD) of 24.3 ± 1.04 in HSCT recipients.. SYBR Green-based q-PCR assay combines simplicity with satisfactory sensitivity and may be suitable for monitoring the immune status of transplant recipients, where TTV loads over time may serve as a marker for immune reconstitution in human plasma samples.

Topics: Adult; Benzothiazoles; Diamines; DNA Virus Infections; Humans; Organic Chemicals; Plasma; Quinolines; Reproducibility of Results; Sensitivity and Specificity; Staining and Labeling; Torque teno virus; Viral Load; Viremia

The aim of this study is to assess a real-time PCR technique on the LightCycler 2.0 with SYBR-Green I detection as compared to another real-time PCR method based on detection with FRET (fluorescence resonance energy transfer) probes for the quantification of CMV DNA.. The two real-time PCR methods were used to test plasma samples from immunocompromised patients with clinically suspected CMV disease, patients under follow-up without symptoms, and healthy adults. A standard curve for quantitative analysis by the SYBR-Green I method was performed with 10-fold diluted solutions of DNA from the CMV Towne strain (ATCC VR-977) cultured in MRC-5 monolayer. In addition, frozen samples from patients positive for CMV pp65 antigenemia were also analyzed and results compared using the two real time PCR methods.. The real-time PCR technique using SYBR-Green I on the LightCycler 2.0 was a highly specific, fast, simple and reliable test to quantify CMV; moreover, it was cost-effective.. Quantification of CMV DNA in plasma using this sensitive, fast, low-cost method was advantageous for the diagnosis and follow up of patients with opportunistic CMV infection, which are increasingly more frequent in our daily hospital clinical practice.

Topics: Adult; AIDS-Related Opportunistic Infections; Antigens, Viral; Benzothiazoles; Bone Marrow Transplantation; Cell Line; Child; Computer Systems; Cytomegalovirus; Cytomegalovirus Infections; Diamines; DNA, Viral; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Humans; Immunocompromised Host; Infant, Newborn; Neoplasms; Neutrophils; Opportunistic Infections; Organic Chemicals; Phosphoproteins; Polymerase Chain Reaction; Postoperative Complications; Quinolines; Reagent Kits, Diagnostic; Reference Standards; Sensitivity and Specificity; Viral Matrix Proteins; Viremia

The persistence of proviral human immunodeficiency virus type 1 (HIV-1) DNA reservoir represents one of the major drawbacks to the total eradication of HIV-1. The quantitative determination of proviral HIV-1 DNA load offers significant therapeutic information, especially when the HIV-1 RNA levels drop below the detectable limits during the highly active retroviral therapy (HAART) treatment. Moreover, the detection of HIV-1 proviral DNA is an important diagnostic marker in the evaluation of HIV-1 infection of newborns of HIV-1 seropositive women.. We evaluated a real-time PCR based on LightCycler technology revealed through SYBR green fluorochrome (SYBR green real-time PCR) to quantify the HIV-1 proviral DNA load in peripheral blood mononuclear cells (PBMC) of HIV-1 seropositive patients.. Firstly, we assessed the SYBR green real-time quantitative PCR for HIV-1 proviral DNA load detection determining the specificity and sensitivity of the assay using the LightCycler system. Secondly, we tested the performance of our SYBR green real-time PCR on 50 HIV-1 seropositive patients under HAART and 20 blood donors.. The results of this study showed that our SYBR green real-time PCR is able to detect five copies of the HIV-1 genome. Moreover, our method revealed HIV-1 proviral DNA in all the 50 HIV-1 seropositive patients ( 627 +/- 1068 HIV-1 proviral DNA copies per 10(6) PBMC, with a range of 30-6300 copies), whereas no positive signal was observed in any PBMC blood donors. Our SYBR green real-time PCR represents a sensitive and useful approach that could be applied both in HIV-1 proviral DNA reservoir determination and in HAART monitoring, particularly when the HIV-1 plasmatic RNA is undetectable.

Topics: Benzothiazoles; Blood Donors; CD4 Lymphocyte Count; Diamines; DNA, Viral; HIV Infections; HIV Seropositivity; HIV-1; Humans; Leukocytes, Mononuclear; Organic Chemicals; Polymerase Chain Reaction; Proviruses; Quinolines; RNA, Viral; Sensitivity and Specificity; Viral Load; Viremia

Studies were performed to determine the effects of Bcell suppression on the pathogenesis of Subgroup J avian leukosis virus (ALV-J) in broiler chickens. Neonatal chickens were treated with cyclophosphamide (CY) or PBS, and then infected with ALV-J (ADOL-7501) at 2 weeks of age. CY treatment induced B cell specific immunosuppression throughout the experiment confirmed by decreased bursal weight, intact lymphocyte mitogenetic activity stimulated by Con A and increased relative subpopulation of CD3-positive cells as measured by flow cytometry. Chickens in this experiment had Mareks disease virus exposure prior to three weeks of age as determined by the presence of lymphocytic infiltration and antibody. Virus neutralizing antibody against ALV-J was first observed at 6 weeks post-infection in some of the infected chickens in the PBS group. As expected, none of the chickens from the CY group and uninfected chickens developed virus-neutralizing antibody. The viremic status was measured by real time RT-PCR using SYBR green I dye. The percentage of viremic chickens was significantly higher, and more chickens had high titered viremia, in the CY treated group. No neoplastic foci consistent with ALVJ infection were observed in any of the experimental chickens. The frequency and intensity of viral antigen expression determined by immunohistochemistry was significantly higher in tissues from CY treated birds than those of PBS treated chickens at 3 weeks post-infection. This study showed that B cell specific immunosuppression with CY treatment in chickens resulted in increase in viremia and viral antigen load in tissues.

Topics: Animals; Avian Leukosis; Avian Leukosis Virus; Benzothiazoles; Body Weight; Bursa of Fabricius; Chickens; Concanavalin A; Cyclophosphamide; Diamines; Flow Cytometry; Immunocompromised Host; Immunohistochemistry; Immunophenotyping; Immunosuppressive Agents; Lymphocyte Activation; Organic Chemicals; Poultry Diseases; Quinolines; Random Allocation; Reverse Transcriptase Polymerase Chain Reaction; RNA, Viral; Spleen; Statistics, Nonparametric; Viremia