New sensitive one-step real-time duplex PCR method for group A and B HIV-2 RNA load.

The Agence Nationale de Recherche sur le Sida et les hépatites virales (ANRS) previously developed a widely used method for HIV-1 RNA quantification (Biocentric). Here, we report the development of a new specific and sensitive method for HIV-2 RNA quantification, based on an adaptation of the existing HIV-1 protocol. The new test is based on TaqMan one-step reverse transcription-quantitative PCR (qRT-PCR) targeting two conserved consensus regions of HIV-2 (long terminal repeat [LTR] and gag).

Field evaluation of the Abbott ARCHITECT HIV Ag/Ab Combo immunoassay.

Background: Fourth generation assays for HIV diagnosis are progressively being introduced into routine services, due to their improvement of diagnosis. In spite of this, HIV diagnosis remains a challenge in sub-Saharan Africa, due to false positive reactivity. There is a continuous need for field evaluations and routine validations of fourth generation HIV tests in African populations.

Tools for the biological diagnosis of HIV infection: 25 years of progress.

The biological tools for an efficient diagnosis of HIV infection have made major progresses during the three last decades. The dynamics of the viral markers during natural infection is well known and provides a strong rationale for the diagnostic strategy. The 4th generation enzyme immunoassays that allow the simultaneous detection of the p24 capsid antigen and HIV antibodies must be used as first-line diagnostic in priority.

A new real-time quantitative PCR for diagnosis and monitoring of HIV-1 group O infection.

The correct diagnosis and monitoring of HIV-1 group O (HIV-O) infection are essential for appropriate patient management, for the prevention of mother-to-child transmission, and for the detection of dual HIV-M/HIV-O infections. HIV-O RNA quantification is currently possible with two commercial kits (from Abbott and Roche), which quantify HIV-M and HIV-O strains indifferently; therefore, they cannot be used for the specific identification of HIV-O infection. We designed a new real-time quantitative reverse transcription PCR (RT-qPCR assay) (INT-O), which we compared with our previous version, LTR-O, and with the Abbott RealTime HIV-1 kit.

Impact of HIV-1 group O genetic diversity on genotypic resistance interpretation by algorithms designed for HIV-1 group M.

Background: HIV-1 group O (HIV-O) is characterized by a high genetic divergence from HIV-1 group M viruses. Little is known about the therapeutic impact of this diversity. The aim of this study was to assess in a large series of samples (1) the genotypic impact of natural polymorphism of the HIV-O reverse transcriptase and protease genes; and (2) the predictive value of resistance interpretation algorithms developed for HIV-1 group M when used for highly mutated HIV-O viruses.

[Human Immunodeficiency Virus type 1 variants of groups N, 0 and P].

The HIV pandemic is caused by viruses of type 1 group M (HIV-M). Beside the majority of these viruses, there are many divergent variants, leading to the definition of HIV-2 and group N, O and P in HIV-1. HIV-1 groups are the result of independent cross-species of viruses from chim- panzees and gorillas living in Western Central Africa.

Baseline genotypic and phenotypic susceptibilities of HIV-1 group O to enfuvirtide.

We assessed the natural genotypic and phenotypic susceptibilities to enfuvirtide of 171 HIV group O (HIV-O) samples and 29 strains, respectively. The N42D resistance-associated mutation in the gp41 region was detected in 98% of cases. The phenotypic assay showed a wide range of baseline susceptibilities, with 50% inhibitory concentrations (IC(50)s) from 4 to 5,000 nM, a range similar to that reported for HIV-1 group M.

Census and analysis of persistent false-negative results in serological diagnosis of human immunodeficiency virus type 1 group O infections.

Human immunodeficiency viruses (HIV) have a high level of genetic diversity. The outlier variants of HIV type 1 (HIV-1) group O are distantly related to HIV-1 group M. Their divergence has an impact on serological diagnosis, with a risk of false-negative results.

RNA amplification of the HIV-1 Pol and env regions on dried serum and plasma spots.

Background: Dried sample spots have molecular applications, but few data are available on conditions of HIV-1 RNA amplification.

Objectives: To determine the impact of (i) the sample type (plasma or serum), (ii) various storage periods, (iii) transfer at ambient temperature of the dried spots via postal mail, and (iv) two different methods of elution-extraction, to amplify partial pol and env genes with a view to both phylogenic and resistance analyses.

Methods: Fourteen samples (dried plasma spot and dried serum spot) from seven patients were stored at 20-25 degrees C for 2, 5 and 7 days.

Prevalence of HIV-2 and HIV-1 group O infections among new HIV diagnoses in France: 2003-2006.

French national surveillance of new HIV diagnoses included the collection of dried serum spots to identify HIV serotypes. Between January 2003 and June 2006, 10,184 new diagnoses were reported. The proportions of HIV-2 and HIV-1 group O infections were 1.

[Virological diagnosis and follow-up of HIV infection. State of the art and situation in Tunisia].

Human immunodeficiency virus (HIV) is a retrovirus infecting approximatively 40 million people worldwide. HIV is characterized by a great variability with epidemiological, diagnostic and therapeutic implications. The course of infection goes through three stages (acute infection, clinical latency and AIDS) with the evolution of virological markers (anti-HIV antibodies, p24 antigenemia, plasma RNA and proviral DNA).

Revisiting the role of neutralizing antibodies in mother-to-child transmission of HIV-1.

We analyzed the association between mother-to-child transmission (MTCT) of human immunodeficiency virus type 1 (HIV-1) and maternal neutralizing antibodies to heterologous primary isolates of various HIV-1 clades, to test the hypothesis that protective antibodies are those with broad neutralizing activity. Our study sample included 90 Thai women for whom the timing of HIV-1 transmission (in utero or intrapartum) was known. The statistical analysis included a conditional logistic-regression model to control for both plasma viral load and duration of zidovudine prophylaxis.

Human immunodeficiency virus serotyping on dried serum spots as a screening tool for the surveillance of the AIDS epidemic.

Many studies have demonstrated the utility of the dried blood spot (DBS) or dried plasma/serum spot (DSS) method for serological and molecular diagnosis of HIV infection. Here, we report on the description of a serotyping assay performed on DSS, and its application to a national surveillance program of HIV variants. We combined serotyping assays that we developed previously to discriminate between HIV-1 and HIV-2, between HIV-1 group O and HIV-1 group M, and between B and non-B subtypes of HIV-1 group M.

Development and validation of an immunoassay for identification of recent human immunodeficiency virus type 1 infections and its use on dried serum spots.

The objective was to develop and to validate an immunossay to identify recent human immunodeficiency virus type 1 (HIV-1) infections that can be used on dried serum spots (DSS). A single, indirect enzyme-linked immunosorbent assay was developed to quantify antibodies toward four HIV-1 antigens: consensus peptides of the immunodominant epitope of gp41 (IDE), consensus V3 peptides, recombinant integrase, and recombinant p24. The parameters of the logistic regression used to classify the samples were estimated on a training sample (210 serum samples) using resampling techniques to get stable estimates and then applied to a validation sample (761 serum samples).

HIV-1 resistance genotyping on dried serum spots.

Objective: To assess the feasibility of HIV-1 group M resistance genotyping on dried serum spots, by testing samples from previously untreated patients, patients on treatment, and patients having stopped treatment, representing a wide genetic diversity panel.

Methods: Serum samples from 62 HIV-1-infected Caucasian and African patients, with viral load values from 715 copies/ml to more than 750,000 copies/ml, were deposited on filter paper. After elution and RNA extraction, nested RT-PCR was used to amplify the protease and RT regions of the pol gene.

Rapid discrimination between human immunodeficiency virus type 2 groups A and B by real-time PCR.

We studied the feasibility of genotyping human immunodeficiency virus (HIV) type 2 groups A and B by real-time PCR. Two group-specific PCRs were developed. Real-time genotyping of 22 samples of genotype A, 10 samples of genotype B, and the isolate of new group H were compared to genotyping by sequencing and phylogeny.

Preliminary results from the new HIV surveillance system in France.

In addition to AIDS surveillance, data on HIV infection are necessary to better follow the dynamics of the epidemic. We report the first results of France's mandatory anonymous HIV notification system, which is linked to a virological surveillance of recent HIV infections and of circulating HIV types, groups and subtypes. HIV notifications are initiated by microbiologists who create an anonymous code of patient's identity.