AEGiS-08IAC: Phenotype associated sequence variation in the third variable domain of the HIV-1 gp120 molecule.

8th International AIDS Conference

Amsterdam, Netherlands — July 19-24, 1992

Phenotype associated sequence variation in the third variable domain of the HIV-1 gp120 molecule.

Int Conf AIDS 1992 Jul 19-24; 8:We60 (abstract no. WeA 1082)
Fouchier RA, Groenink M, Kootstra NA, Tersmette M, Huisman HG, Miedema F, Schuitemaker H; Central Laboratory of The Netherlands Red Cross Blood Transfusion Service, Amsterdam.

OBJECTIVES: The third variable (V3) domain of HIV-1 gp120 elicits type specific neutralizing antibodies, and contains a type specific T-cell epitope. V3 is critical for gp120 function, and has been implied in determining the virus phenotype including fusion capacity and monocytotropism. Fusion capacity of virus isolates has been shown usefull as a prognostic marker for disease progression. Comparison of small numbers of isolates have not provided insight as how the high degree of sequence variability may give rise to large subgroups of HIV-1 strains.

METHODS: PCR amplification of V3 domains from a large panel (60 isolates from 30 infected persons) of primary isolates with well defined syncytium inducing capacity and monocytotropism was performed, followed by direct sequencing of the PCR products.

RESULTS: Sequence analysis of V3 domains from virus isolates with well defined biological phenotypes revealed that fast-replicating, syncytium-inducing (SI)/non-monocytotropic isolates contained V3 sequences with a significantly higher positive charge than those of slow-replicating, non-syncytium-inducing (NSI)/monocytotropic isolates. On either side of the loop, midway the cysteine and the central GPG motif, a highly variable amino acid residue is located that was negatively charged or uncharged in NSI/monocytotropic isolates whereas in SI/non-monocytotropic isolates either one or both were positively charged. These substitutions result in changes in predicted secondary structure of the V3 domain. Site directed mutagenesis experiments of the critical amino acid residues are now in progress to formerly prove the functional relevance of our findings.

CONCLUSIONS: Our data indicate that the V3 domain is an important determinant for the biological phenotype of HIV-1 isolates and further suggest that an efficacious AIDS vaccine conferring protection to the relevant HIV-1 variants should include V3 sequences specific for NSI/monocytotropic in addition to the now generally used SI/non-monocytotropic isolates.

Keywords: AEGIS, HIV-1, Variation (Genetics), Phenotype, Giant Cells, Polymerase Chain Reaction, Sequence Analysis, genetics, ICA8
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