Marie Leoz

A new human immunodeficiency virus derived from gorillas.

We have identified a new human immunodeficiency virus in a Cameroonian woman. It is closely related to gorilla simian immunodeficiency virus (SIVgor) and shows no evidence of recombination with other HIV-1 lineages. This new virus seems to be the prototype of a new HIV-1 lineage that is distinct from HIV-1 groups M, N and O. We propose to designate it HIV-1 group P.

Differential Regulation of NF-κB-Mediated Proviral and Antiviral Host Gene Expression by Primate Lentiviral Nef and Vpu Proteins.

SUMMARY NF-κB is essential for effective transcription of primate lentiviral genomes and also activates antiviral host genes. Here, we show that the early protein Nef of most primate lentiviruses enhances NF-κB activation. In contrast, the late protein Vpu of HIV-1 and its simian precursors inhibits activation of NF-κB, even in the presence of Nef. Although this effect of Vpu did not correlate with its ability to interact with β-TrCP, it involved the stabilization of IκB and reduced nuclear translocation of p65. Interestingly, however, Vpu did not affect casein kinase II-mediated phosphorylation of p65. Lack of Vpu was associated with increased NF-κB activation and induction of interferon and interferon-stimulated genes (ISGs) in HIV-1-infected T cells. Thus, HIV-1 and its simian precursors employ Nef to boost NF-κB activation early during the viral life cycle to initiate proviral transcription, while Vpu is used to downmodulate NF-κB-dependent expression of ISGs at later stages.

Diagnosis and monitoring of HIV-1 group O-infected patients in Cameroun.

Objective:To define a routine algorithm for the specific diagnosis and complete follow-up of HIV-1 group O (HIV-O) infections in Cameroun. Methods:During 18 months, samples referred to Centre Pasteur du Cameroun for HIV testing or viral monitoring were screened for HIV-O infection with an in-house serotyping assay. HIV-O viral load was quantified by real-time polymerase chain reaction in the LTR gene and resistance genotyping was performed on pol and env sequences. Results:Of the 7030 samples tested, 78 HIV-O infections (1.1%) were identified, including 7 M and O dually seroreactive samples (9%). All treatment-naive patients and 59% of the patients receiving HAART had detectable viral loads. Analysis of pol sequences from 15 treatment-naive patients revealed a high number of polymorphisms in the protease region, with natural residues implicated in genotypic resistance to tipranavir and saquinavir for HIV-1 group M according to the Agence Nationale de Recherches sur le Sida et les Hépatites virales algorithm. Six patients (40%) harbored the 181C mutation conferring natural resistance to nonnucleoside reverse transcriptase inhibitors. Among antiretroviral-treated patients, major resistance mutations described for HIV-1 group M were found. Conclusions:HIV-O prevalence remains relatively low in Cameroun. The cocirculation of groups M and O in this country leads to replicative dual infections. HIV-O-infected patients in this region can now benefit from effective and specific tools for a complete monitoring of infection. However, further studies are needed to understand long-term response to antiretrovirals of these complex variants.

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. Methods:Sixty-eight antiretroviral-naive and 9 highly antiretroviral-experienced HIV-O-infected patients were included. The viruses were sequenced and resistance-associated mutations were identified using 3 different algorithms (Agence Nationale de Recherches sur le SIDA et les hépatites virales, Rega, Stanford). Results:All HIV-O samples naturally exhibited the A98G and V179E resistance mutations in the reverse transcriptase region; 54% of samples presented the Y181C mutation, conferring resistance to nonnucleoside reverse transcriptase inhibitors. Twelve minor resistance mutations, present in more than 75% of the protease sequences, led to the different algorithms giving discrepant results for nelfinavir and saquinavir susceptibility. A marked virological response was observed in 8 of the 9 antiretroviral-experienced patients, despite the prediction of limited activity of the combination for 5 to 8 patients according to the algorithm used. Conclusions:The high level of natural polymorphism in HIV-O genes, and the important discrepancies between genotypic resistance interpretation and the virological response, emphasize the need for resistance algorithm rules better adapted to HIV-O.

First evidence of a HIV-1 M/O recombinant form circulating outside Cameroon.

HIV-1 are now classified into four groups: M (major), O (outlier), N (non-M – non-O), and a new group P, the prototype of which is the divergent strain recently characterized in a Cameroonian patient [1]. Recombination between HIV strains is a very frequent phenomenon, greatly increasing genetic div

A New Real-Time Quantitative PCR for Diagnosis and Monitoring of HIV-1 Group O Infection

ABSTRACT 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. Specificity was assessed with 27 HIV-1 group M strains and the prototype strain of group P. Clinical performances were analyzed by using 198 stored plasma samples, representative of HIV-O genetic diversity. Analytical sensitivity, repeatability, and reproducibility were also determined. The detection limit of the INT-O assay was 40 copies/ml, and its specificity was 100%. The repeatability and reproducibility were excellent. Analysis of clinical samples showed a good correlation between the INT-O and LTR-O assays (r = 0.8240), with an improvement of analytical sensitivity. A good correlation was also obtained between the INT-O and Abbott assays (r = 0.8599) but with significantly higher values (0.19 logs) for the INT-O method, due to marked underquantifications for some patients. These results showed that HIV-O genetic diversity still has an impact on RNA quantification. The new assay, INT-O, allows both the specific diagnosis of HIV-O infection and the quantification of diverse HIV-O strains. Its detection limit is equivalent to that of commercial kits. This assay is cheap and suitable for use in areas in which strains of HIV-1 groups M and O cocirculate.

Baseline Genotypic and Phenotypic Susceptibilities of HIV-1 Group O to Enfuvirtide

ABSTRACT 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 (IC50s) from 4 to 5,000 nM, a range similar to that reported for HIV-1 group M. Thus, despite the natural genotypic resistance conferred by the N42D signature mutation, HIV-O variants appear to be phenotypically susceptible. Enfuvirtide could therefore potentially be used in antiretroviral treatments for HIV-O-infected patients.

Circulation of multiple patterns of unique recombinant forms B/CRF02_AG in France: precursor signs of the emergence of an upcoming CRF B/02.

Background:HIV-1 group M is characterized by substantial genetic diversity, and includes nine subtypes, more than 45 circulating recombinant forms (CRFs), and numerous unique recombinant forms (URFs). In France, the epidemic is characterized by predominance of subtype B strains, increasing prevalence of non-B subtypes (CRF02_AG being the most prevalent) and increasing at-risk behaviour in the MSM population. The high prevalence and co-circulation of B and CRF02_AG strains in this population raise the possibility that recombinant forms might emerge and spread. Methods:Samples from seven patients (five being MSM) were selected on the basis of subtyping discordances in different regions. The pattern of each near full-length genome of the viruses was characterized. The relationships between the newly and previously described B/CRF02_AG URFs were analysed using phylogenetic networks. Single genome amplification was used to search for the parental strains and confirmation of the breakpoints. Results:Seven unique recombination patterns were identified, breakpoints being found throughout the genomes, with hotspots in pol and accessory genes. No link was observed with the previous forms, but the CRF02 regions of two new viruses indicated that they are phylogenetically associated, suggesting a common ancestral strain. No evidence of circulating parental strains was found. Conclusion:This description of seven URFs involving subtype B and CRF02_AG highlights the growing complexity of HIV molecular epidemiology in France. These multiple patterns, found mostly in MSM, and the hypothesis of a better fitness of some recombinant strains, argue for a context that could lead to the genesis of CRFB/02_AG strains in France.

Characterization of CRF56_cpx, a new circulating B/CRF02/G recombinant form identified in MSM in France.

Several B/CRF02_AG Unique Recombinant Forms (URFs) have previously been identified in France. Here we show that one of them (URF5_B/02/G) is emerging in MSM, a high-risk population where HIV incidence and number of superinfections are increasing. We describe this new Circulating Recombinant Form, CRF56_cpx, estimate the time to its most recent common ancestor, investigate its origins and show that it probably shares common ancestors with strains from the East Mediterranean.

The Two-Phase Emergence of Non Pandemic HIV-1 Group O in Cameroon

Unlike the pandemic form of HIV-1 (group M), group O viruses are endemic in west central Africa, especially in Cameroon. However, little is known about group O’s genetic evolution, and why this highly divergent lineage has not become pandemic. Using a unique and large set of group O sequences from samples collected from 1987 to 2012, we find that this lineage has evolved in successive slow and fast phases of diversification, with a most recent common ancestor estimated to have existed around 1930 (1914–1944). The most rapid periods of diversification occurred in the 1950s and in the 1980s, and could be linked to favourable epidemiological contexts in Cameroon. Group O genetic diversity reflects this two-phase evolution, with two distinct populations potentially having different viral properties. The currently predominant viral population emerged in the 1980s, from an ancient population which had first developed in the 1950s, and is characterized by higher growth and evolutionary rates, and the natural presence of the Y181C resistance mutation, thought to confer a phenotypic advantage. Our findings show that although this evolutionary pattern is specific to HIV-1 group O, it paralleled the early spread of HIV-1 group M in the Democratic Republic of Congo. Both viral lineages are likely to have benefited from similar epidemiological contexts. The relative role of virological and social factors in the distinct epidemic histories of HIV-1 group O and M needs to be reassessed.