DOI: 10.1097/QAD.0b013e3283355659
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PMID: 20386379
Issn Print: 0269-9370
Publication Date: 2010/04/24
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Excerpt
In May 2008, a 25-year-old Cameroonian woman (RBF208) living in France attended a consultation at Reims University Hospital (north-east France). She had been diagnosed with HIV infection in 2003 in the Paris suburbs, but the initiation of highly active antiretroviral therapy (HAART) was delayed because this patient was lost to follow-up a few months after diagnosis. On arrival at Reims Hospital, this patient was thus antiretroviral drug-naive and presented with severe immunodepression (CD4 cell count = 6 cells/μl) and AIDS, but no detectable plasma viral load (pVL) in the HIV-M-specific Cobas TaqMan test (Roche Diagnostics, Meylan, France). This immunovirological discordance was investigated with the plasma samples available, dating from May 2008, with two in-house Env serotyping assays, to identify the group to which the strain belonged [7,8], RNA quantification tools (RealTime HIV-1 assay, Abbott Molecular, Abbott Park, Illinois, USA; in-house HIV-O-specific technique [9]; and the Generic HIV viral load assay [Biocentric, Bandol, France] specific for HIV-M [10]), and group-specific PCRs targeting the Pol and Env regions [4,11,12]. The near full-length genome of strain RBF208 was amplified and sequenced, from RNA and proviral DNA, with procedures adapted from [1].
Env serotyping assays revealed a typical HIV-M infection, with no reactivity for group O-specific antigens. Conversely, pVL was 4.8 log copies/ml and 5.1 log copies/ml with the RealTime HIV-1 and in-house HIV-O-specific assays, respectively, whereas no virus could be detected in the plasma with the Generic HIV and Cobas Taqman tests, consistent with a group O strain. Using group-specific PCRs, only the HIV-O Pol region [protease, reverse transcriptase (RT) and integrase] was detected in plasma and peripheral blood mononuclear cells. The Env/Gp41 region was first not amplified by any classical group M or O primers, but with alternative primers, revealing a HIV-M to HIV-O switch in this region. The characterization of the near full-length genome showed a 5′-O-M-O-3′ recombinant form, with a first O/M breakpoint in the first codon of Vpr (3' end of Vif) and a second M/O breakpoint towards the 3′ end of Gp41 (Fig. 1a, b). Phylogenetic analyses confirmed that the Pol (integrase) and Env (Vpr-to-Gp120) regions, belonged, respectively, to group O (Fig. 1c) and to group M (subtype D, Fig. 1d), and that strain RBF208 was unrelated to the other M/O recombinants previously described. The full-length sequences obtained from plasma RNA and intracellular DNA displayed an identical mosaic pattern.
This first characterization of an M/O intergroup recombinant circulating outside Cameroon was based on discordances between pVL quantification techniques, leading to the suspicion of an HIV-O infection and paradoxical Env serotyping reactivities indicating HIV-M infection. The lack of RNA and DNA detection with group-specific primers binding to the Gag-to-Vif region for HIV-M and the Vpr-to-3'Env region for HIV-O suggested the absence of putative parental strains.
