11th International AIDS Conference Vancouver, British Columbia — July 7-12, 1996

Int Conf AIDS 1996 Jul 7-12; 11:224 (abstract no. Tu.A.371)
Saragosti S, Loussert-Ajaka I, Mauclere P, Descamps D, Bouchaud O, Simon F, Brun-Vezinet F; I.C.G.M, Institut Fournier, Paris, France. Fax: 33-1-45.89.74.05. E-mail: sentob@citi2.fr.

OBJECTIVE: To characterize the genotype and the phenotype of group O viruses isolated from patients living in France and in Cameroon.

METHODS: Strains isolated by coculture on PBMC were studied. DNA was amplified using group O specific primers for the gag and C2V3 env regions and sequenced (Applied 373A sequencer). Phylogenetic trees were inferred using PHYLIP package (SEQBOOT, DNADIST, NEIGHBOR JOINING or FITCH, and CONSENS). Phenotypic sensitivity to nucleosides and non nucleosides reverse transcriptase inhibitors were determined using a standardized in vitro test which evaluates RT inhibition, considering the replication kinetics of each strain. Syncytia formation onto MT2 cells were studied using standard technics and correlation with the V3 loop amino acid sequence was assessed. Antigenic consequences of the strain variability was studied by the serological reactivity against ANT70 V3 peptides.

RESULTS: As already described, the inter M and O genetic distances clearly defined two different HIV-1 groups forming a double star phylogenetic pattern. Inter M and O groups genetic distances ranged from 39 to 49% for the C2V3 env region and from 24 to 32% for the gag region (our work, J. Virol, 1995, 69: 5640). However, the analysis derived from the new of group O strains sequences suggests that the inter M and O genetic distances may be closer than previously published. This variability is correlated with the large pattern of reactivity against ANT70V3 peptide.

CONCLUSIONS: The emergence of highly divergent viruses must be taken in account in HIV diagnosis, in vaccine and in drug development. Surveillance of newly recognized HIV-1 group O viruses is important in order to monitor the incidence of these viruses and the emergence of unknown viruses strains. The use of a serological algorithm for the detection of HIV-1 group O viruses and other variants (Mauclere et al, in preparation) was possible after the setting up of a surveillance network. This approach which allowed us already to characterize 18 group O viruses in France, confirms the need for an extensive epidemiological study.

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TuA371

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