High natural polymorphism in the gag gene cleavage sites of non-B HIV type 1 isolates from Gabon

The main goal of the present study was to determine the frequency of substitutions in the cleavage sites (CS) of gag gene among non-B HIV-1 isolates from Gabon. Fifty plasma specimens, collected in 2010-2011, from HIV-1-infected patients failing first-line antiretroviral (ARV) regimens (constituted of two nucleoside reverse transcriptase inhibitors+one nonnucleoside reverse transcriptase inhibitor) (n = 38) and from HIV-1-infected individuals untreated with ARV (n = 12) were analyzed in the gag and gag-pol cleavage sites. Compared to HXB2 reference sequence, the total median number of substitutions in gag and gag-pol CS was 10 (range, 5-18). The cleavage site p2/NC was the most variable of the four gag CS with 100% (50/50) isolates carrying at least 1 substitution (range, 1-9). The two gag-pol TFP/p6(pol) and p6(pol)/PR CS sites were also highly variable (at least one substitution, 50/50, 100% in both cases). Substitutions at position G381 (p2/NC), L449 (p1/p6(gag)), and K444 (TFP/p6(pol)) were significantly more frequent in CRF02_AG strains, compared to other non-B strains (30.4% vs. 3.7%, p = 0.03; 87.0% vs. 59.3%, p = 0.03; and 91.3% vs. 59.3%, p = 0.01, respectively). Other non-B subtypes were significantly more likely to harbor substitutions at position N487 (p6(pol)) (70.4%) than CRF02_AG (39.1%) (p = 0.02). In Gabon, gag and gag-pol cleavage sites were highly polymorphic in protease inhibitor-naive patients harboring non-B HIV-1 strains. In sub-Saharan Africa, further studies are definitively required to better understand the impact of gag mutations among subjects receiving second-line LPV/r-containing regimens (monotherapy or triple combinations)

Mimivirus: leading the way in the discovery of giant viruses of amoebae

International audienceThe accidental discovery of the giant virus of amoeba -Acanthamoeba polyphaga mimivirus (APMV; more commonly known as mimivirus) -in 2003 changed the field of virology. Viruses were previously defined by their submicroscopic size, which probably prevented the search for giant viruses, which are visible by light microscopy. Extended studies of giant viruses of amoebae revealed that they have genetic, proteomic and structural complexities that were not thought to exist among viruses and that are comparable to those of bacteria, archaea and small eukaryotes. The giant virus particles contain mRNA and more than 100 proteins, they have gene repertoires that are broader than those of other viruses and, notably, some encode translation components. The infection cycles of giant viruses of amoebae involve virus entry by amoebal phagocytosis and replication in viral factories. In addition, mimiviruses are infected by virophages, defend against them through the mimivirus virophage resistance element (MIMIVIRE) system and have a unique mobilome. Overall, giant viruses of amoebae, including mimiviruses, marseilleviruses, pandoraviruses, pithoviruses, faustoviruses and molliviruses, challenge the definition and classification of viruses, and have increasingly been detected in humans