Teresa Venenno

Spreading of HIV-1 subtype G and envB/gagG recombinant strains among injecting drug users in Lisbon, Portugal.

We have evaluated the genetic diversity of HIV-1 strains infecting injecting drug users (IDUs) in Lisbon, Portugal. Heteroduplex mobility assay and/or phylogenetic analysis revealed that env (C2V3C3 or gp41) subtype B is present in 63.7% of the 135 viral samples studied, followed by subtypes G (23.7%), A (6.7%), F (5.2%), and D (0.7%). Similar analysis of gag (p24/p7) performed on 91 of the specimens demonstrated that 49.5% of the infections were caused by subtype G viruses; other gag subtypes identified were B (39.5%), F (3.3%), A and D (1.1.% each), and the recombinant circulating form CRF02_AG (5.5%). Discordant env/gag sub-types were detected in 34.1% of the strains and may reflect the presence of dual infections and/or recombinant viruses. The presumptive B/G recombinant form was highly predominant (21 of 31). The genetic pattern of HIV-1 subtype B and G strains is suggestive of multiple introductions and recombination episodes and of a longstanding presence of both subtypes in the country. C2V3C3 amino acid sequences from IDU-derived subtype G viruses presented highly significant signatures, which distinguish the variants from this transmission group. The unusually high prevalence of subtype G sequences (34.1%), independent of the geographic origin of the infected individuals, makes this IDU HIV-1 epidemic unique.

Hepatitis C virus subtypes circulating among intravenous drug users in Lisbon, Portugal†

Hepatitis C virus (HCV) infects 2–3% of the world population and intravenous drug consumption is the leading cause of transmission in industrialized countries. The unavailability of data on the molecular epidemiology of HCV infection in Portugal prompted the study of HCV subtypes circulating among intravenous drug users residing in the Lisbon metropolitan area and sampled about 10 years apart (1998–2000 and 2008–2009). Partial coding sequences for E1 and/or NS5B were obtained from 124 individuals with HCV viremia, both mono‐infected and co‐infected with HIV. Phylogenetic analysis showed that, for both time periods, the most prevalent subtypes were 1a and 3a, found, altogether, in 64.9% and 71.6% of the individuals, respectively for the first and the second sampling periods. However, genotype 4 viruses (subtypes 4a and 4d), introduced later, as inferred by comparison of intra‐subtype genetic distances, were also relatively frequent even one decade ago (24.6%). This HCV subtype profile for Portuguese intravenous drug users is in agreement with those described for other southern European countries when in association with drug consumption. With the exception of subtype 1b, phylogenetic trees did not show clustering of the Portuguese sequences, but rather phylogenetic mixing of HCV sequences from different geographic origins, as described previously in other Western countries and suggestive of a large international transmission network. Consistent with the low recombination rates reported for HCV, only one sample revealed discordant subtypes for the two regions analyzed (4d in E1 and 4a in NS5B), representing a potential new recombinant that deserves further analysis. J. Med. Virol. 83:608–615, 2011.

Genetic characterization of HIV type 1 and type 2 from Bissau, Guinea-Bissau (West Africa)

Previous studies from Guinea-Bissau (West Africa) have demonstrated a unique epidemiology with respect to both HIV-1 and HIV-2 infection. In order to evaluate the prevalence and dynamics of HIV-1 and HIV-2 subtypes in Bissau, the capital city of Guinea-Bissau, a cross-sectional study was set up using serological and molecular techniques. Plasma samples from 103 individuals were screened for HIV-1 and HIV-2 antibodies by ELISA and Western-blot. Seropositive results were confirmed by PCR amplification of proviral sequences in primary peripheral blood mononuclear cells (PBMC) with env and LTR primer sets for HIV-2 and env, LTR and pol primers for HIV-1. A total of 38/103 individuals were HIV-seroreactive (four HIV-1, 15 HIV-2, 19 HIV-1/HIV-2). A total of eight out of 19 dually seropositive specimens showed double PCR amplification of HIV-1 and HIV-2 proviral sequences, accounting for 21% of the infected individuals. In the remaining 11 individuals either HIV-2 or HIV-1 sequences were detected, the majority (n=9) amplifying only HIV-2. These screening data demonstrate a high discrepancy between serology and PCR results for dually seroreactive samples, Western-blot giving an overestimation of double infection. Additionally, HIV-1 strains were subtyped by heteroduplex mobility assay (HMA) on the basis of gp120 sequences. Subtyping of HIV-2 was carried out by DNA sequencing and phylogenetic analysis of env V3 molecular clones. For both HIV-1 and HIV-2 strains circulating in Bissau, our results indicate dominance of subtype A.

Genetic Variability of Human Immunodeficiency Virus Type 2 C2V3 Region within and between Individuals from Bissau, Guinea-Bissau, West Africa

The V3 loop of both HIV-1 and HIV-2 is characterized by a high degree of genetic variation. To investigate the spectrum of HIV-2 variability in nature we have focused on the C2V3 region of Env and analyzed 108 viral sequences obtained from uncultured peripheral blood mononuclear cells obtained from 16 HIV-2-seropositive individuals from Bissau (Guinea-Bissau). The estimated values of genetic divergence between individuals were higher than those calculated from sequence information collected in a single individual. We have also found that the sequences surrounding the V3 loop contribute significantly to the overall genetic diversity of the C2V3 region of HIV-2 gp105, while the V3 loop itself seems to be rather conserved. Phylogenetic analysis demonstrated that all the individuals enrolled in this study were infected with HIV-2 subtype A viruses.

Longstanding presence of HIV-2 infection in Guinea-Bissau (West Africa).

We have retrospectively studied the seroprevalence of the human immunodeficiency virus (HIV) in Guinea-Bissau in a sample of sera collected from the whole country in 1980. We tested a total of 1248 individuals and found 11 individuals who were seropositive for HIV-2 but there were no HIV-1 seropositive samples. The mean age of the HIV-2 seropositive people was significantly higher than the age of the seronegative individuals. In the different areas surveyed, the HIV-2 seroprevalence ranged from 0 to 2.5%. A central region of the country, grossly centred in the capital city of Bissau, presented the highest prevalence of HIV-2 seropositivity (>2%), which contrasts with its virtual absence from the more remote rural areas located near the borders with the neighbouring countries. The overall seroprevalence found for HIV-2 in this study is 0.9% (1.8%, when considering the adult seroprevalence only), which proves that the virus was definitely circulating in Guinea-Bissau at the beginning of the 1980s.

Follow-up Study of Intrahost HIV Type 2 Variability Reveals Discontinuous Evolution of C2V3 Sequences

Sequence change dynamics in the highly polymorphic C2V3 region of the envelope glycoprotein gp105 coding sequence of HIV-2 was studied for two HIV-2 seropositive Guinean individuals over a 5-year period. Proviral DNA was amplified by PCR from uncultured peripheral blood mononuclear cells (PBMC), cloned, and sequenced. Amino acid sequence alignment and phylogenetic analysis showed distinct viral populations for the three collected samples (1992, 1995, and 1997) for both individuals. A discontinuous replacement of sequences suggests activation of latent viruses present in reservoirs, a process that has been documented for the HIV-1 infection but unreported so far for HIV-2. The nucleotide sequences presented in this work have been assigned accession numbers AJ400276 to AJ400319.