7th Conference - Abstract 213

Newly Derived HIV-1 Group N and SIVcpz (P.t.t.) Strains Cluster Together in the HIV-1/SIVcpz Lineage

S. SOUQUIERE¹, P. ROQUES², A. AYOUBA³, E. NERRIENET³, D. L. ROBERTSON⁴, M. MULLER-TRUTWIN⁵, P. MAUCLERE^3&5, F. BARRE-SINOUSSI⁵, and F. SIMON*¹. ¹CIRMF, Franceville, Gabon; ²CEA, Fontenay aux Roses, France; ³Ctr. Pasteur, Yaounde, Cameroon; ⁴Oxford Univ., UK; and ⁵Inst. Pasteur, Paris, France

Studies have shown a close relationship between SIVcpz from common chimpanzees (Pan troglotydes troglotydes) and HIV-1 group N. However, only three SIVcpz (P.t.t.) strains (GAB, US and Cam3) and one HIV-1 N (YBF30) have so far been fully characterized, and a second group N strain (YBF105) partially sequenced in pol. In order to study the group N epidemiology and to better define the HIV-1/SIVcpz relationship, new group N and SIVcpz strains were derived. 5464 HIV-1 positives samples collected in Cameroon (1997-99) were tested using group M, O and N-specific V3 peptides EIA. 97% samples reacted with the group M peptide, 2% with the group O peptide and three samples (0.1%) with group N peptide. A 150 bp fragment of integrase was amplified for these three new group N samples designated YBF106, YBF115 and YBF116. In addition, 3356 bp from gag-pol of YBF106 was obtained. Phylogenetic analysis showed a monophyletic clustering of all five group N strains in integrase and preliminary analysis in gag and env confirmed this clustering. Using the same peptide assay, 118 wild caught chimpanzees captured during infancy in Cameroon (29), Gabon (53), Congo (36) were tested. Only two P. t. troglotydes, from Cameroon, were positive, reacting specificaly with the N peptide. SIVcpz strains Cam3 and Cam5 were isolated and fully sequenced. The HIV-1 group N and SIVcpz strains form a monophyletic cluster. These new sequences confirm a primate-human cross-species transmission and the circulation of group N strains in the human population. The low prevalence in juvenile chimps points to the need for epidemiological studies of adult primate populations to find the missing links in the origin(s) of HIV groups M and O.

Key Words: group N, origins, SIVcpz