Biomedical subjects

Edouard Tuaillon

Publications and source records attributed to Edouard Tuaillon.

4 recordsLinked to original sources

PubMed2006

Detection of memory B lymphocytes specific to hepatitis B virus (HBV) surface antigen (HBsAg) from HBsAg-vaccinated or HBV-immunized subjects by ELISPOT assay.

To improve the investigation of the role of human memory B lymphocytes following hepatitis B virus (HBV) infection or vaccination, we developed a method to characterize circulating memory B cells specific to hepatitis B surface antigen (HBsAg). Our approach combined: (1) purification of CD19+ cells, (2) CD40-CD40L polyclonal stimulation, and (3) enumeration of memory B cells differentiated into anti-HBs antibody (Ab)-secreting cells (HBs-SCs) by a HBs-ELISPOT assay. In this way, HBs-SCs were detected in 17 HBsAg-vaccinated and nine HBV-immunized subjects including four individuals with serum anti-HBs Ab levels < 10 mIU/ml, but not in six controls. IgG+, IgA+ plus IgM+ HBs-SCs, representing 5-1736 cells/10(6) circulating B cells and 0.02-0.58% of total immunoglobulin-SCs generated by the B cell polyclonal stimulation, were counted by an Ig two-colour ELISPOT assay. In addition, anti-HBs Abs were found in 8/15 supernatants recovered from B cell cultures which contained HBs-SCs, suggesting that the HBs-ELISPOT assay is more reliable in tracking HBsAg-specific memory B cells than ELISA measurement of anti-HBs Abs secreted in supernatants. This new approach could be useful to explore the presence and the longevity of HBsAg-specific memory B cells in vaccinated and immunized subjects, in chronic HBV infection and after liver transplantation for HBV-related disease.

Antibody-Producing Cells↗

PubMed2006

Detection of a large T-cell reservoir able to replicate HIV-1 actively in breast milk.

In breast milk and paired blood samples of nine HIV-1-infected lactating women, we undertook a study to detect a CD4 T-cell reservoir and to investigate its capacity to enter viral production after activation. Breast milk-infected CD4 T cells have a greater capacity to produce viral particles actively than blood CD4 T cells. This observation may explain the apparent paradox of a transmissible viral infection from a body fluid with a low viral concentration.

CD4 Lymphocyte Count↗

PubMed2004

Phenotypic susceptibility to nonnucleoside inhibitors of virion-associated reverse transcriptase from different HIV types and groups.

OBJECTIVES: To evaluate a phenotype assay based on plasma reverse transcriptase (RT) to assess HIV susceptibility to nonnucleoside RT inhibitors (NNRTIs). To compare RT-based phenotype with recombinant virus assay (RVA) phenotype- and genotype-based analysis. To assess group O and HIV-2 susceptibility to NNRTIs in correlation with genotype polymorphisms. METHODS: RT activity was quantified and its susceptibility to efavirenz, nevirapine, and delavirdine measured as drug concentration resulting in 50% inhibition. RT phenotype was compared with genotype analysis. Eighteen plasma samples from 14 group M- and culture supernatants from 4 group M-, 9 group O-, and 7 HIV-2-infected patients were investigated. RT-based and RVA-based phenotypes were compared for identical plasma from 9 group M-infected patients. RESULTS: RT-based and RVA-based phenotypes were in complete agreement. RT-based phenotype- and genotype-predicted susceptibility were concordant for all but 1 group M samples. One plasma showed susceptibility to 3 NNRTIs by phenotypes, despite the presence of 101E and 106I/V residues. The HIV-2 RTs were totally resistant to the NNRTIs tested. Among HIV-1 group O, 6 were totally resistant to NNRTIs independently of the presence of the 181C mutation and 3 were susceptible to some NNRTIs. CONCLUSION: Plasma RT-based phenotype could be useful as a simple alternative for monitoring resistance to NNRTIs. This assay is suitable for highly divergent strains. It would be particularly useful for large epidemiologic survey of the natural HIV polymorphism and the potential impact in emergence of drug resistance, particularly to nevirapine, widely used to prevent mother-to-child transmission.

Anti-HIV Agents↗

PubMed2003

A new quantitative HIV load assay based on plasma virion reverse transcriptase activity for the different types, groups and subtypes.

BACKGROUND: Plasma viral load monitoring is an integral part of the standard of care for HIV-infected patients in industrialized countries. In developing countries, viral load assay is either unaffordable or hindered by on-site maintenance and/or technical problems. OBJECTIVES: To evaluate a new and simple quantitative assay for plasma HIV reverse transcriptase (RT) activity; and to compare RT activity-based and RNA-based quantification in plasma samples from patients infected by different subtypes of HIV-1 group-M, HIV-1 group-O and HIV-2. METHODS: The RT-based viral load assay involves separation of the virion-protected RT and quantification of its activity with an enzyme immunoassay. Plasma viraemia was quantified both by RT activity and by RNA copies in 322 samples from 236 HIV-1 group M-infected patients, including serial samples from 54 patients. Samples from 49 patients infected by HIV-1 group O or HIV-2 were also tested. RESULTS: RT activity and RNA copies were detected in 70% of plasma samples; respectively 25% and 1% of samples contained detectable RNA copies or RT activity alone. Measured RT activity corresponded to 48%, 96% and 100% of samples with 1.7-4.0 log(10), 4.1-4.8 log(10) and 4.9-6.7 log(10) RNA copies/ml, respectively. The values of the two assays correlated independently of the HIV subtype (P < 0.0001) and group/type (P < 0.03). Patient follow-up showed a similar pattern of viraemia with the two assays. CONCLUSION: Plasma RT activity assay is a simple, cheap and reliable alternative for HIV viral load determination. As such, it could be particularly valuable for diagnosis and treatment monitoring in developing countries.

HIV Infections↗