9th Conference on Retroviruses and Opportunistic Infections Seattle, Washington - February 24 -February 28, 2002

Conf Retroviruses Opportunistic Infect 2002 Feb 24-28;9:abstract no. 17
S. Jost¹, S. Yerly¹, D. Kaufmann², M. Monnat², A. Telenti², J. P. Chave², L. Kaiser¹, P. Burgisser², M. Flepp³, and L. Perrin^1
1Geneva Univ.; ²Lausanne Univ.; and ³Zurich Univ., Switzerland

BACKGROUND: The analysis of HIV-1 sequences in PHI presents a unique opportunity to assess the dynamic of spreading of HIV strains in defined geographic areas. We detected a J recombinant subtype for the first time in 1999, in seroconverting IVDUs in the Lausanne area (200.000 inhabitants).

METHODS: 61 plasma from seroconverting or recently (< 1 year) infected IVDUs were collected in 7 AIDS centers in Switzerland between January 1996 and September 2001. Sequencing and subtyping of reverse transcriptase (RT), protease (Pr), and in some cases env (C2V3) and gag (p17) regions were performed. Phylogenetic analyses were performed using the PHYLIP package. Genetic trees were constructed by the NEIGHBOR and DNADIST programs. Subtypes were confirmed by simplot analyses and BLAST against HIV-1 Los Alamos database. Genetic data were confronted with epidemiological data.

RESULTS: Among the 61 IVDUs, 33 were from the Lausanne area. Based on Pr and RT sequences, all the 28 IVDUs from Switzerland outside the Lausanne area carried a B subtype virus. Those from Lausanne were either of the B subtype (N=14) or of the J subtype (N=19) for Pr and RT sequences, 3 seroconverted in 1999 (0 B, 3 J), 12 in 2000 (2 B, 10 J), and 18 in 2001 (12 B, 6 J). The gag p17 sequences of all patients with the J Pr/RT subtype segregated together and were closely related to A reference strains. The C2V3 sequences were available in 14 IVDUs with J Pr/RT subtype: 3 C2V3 sequences segregated with B reference strains and 11 with A reference strains. These results were confirmed in subsequent plasma samples. The nucleotide difference between B and A C2V3 sequences was on average 22%. There was a documented epidemiological link between 2 of the 3 individuals with B C2V3 sequences. For individuals with J Pr/RT and A C2V3 recombinant form, a cluster of 11 individuals was observed for RT (bootstrap, 98) and was confirmed for C2V3. An epidemiological link and documented cocaine use were established in this subgroup. Among 210 PHI non-IVDUs individuals tested between 1996 and 2001 in Switzerland, this J/A recombinant form has been detected only in 3 individuals infected through heterosexual contacts.

CONCLUSIONS: Unlike the recombinant A/B epidemic in Leningrad IVDUs, the spread of the recently introduced recombinant J/A in IVDUs remains restricted to a relatively small area in Switzerland and almost exclusively in IVDUs. This study also indicates that, even in a small population, recombination events can be detected (A and B C2V3 within the context of a novel recombinant virus).

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