GENETIC-HETEROGENEITY OF THE V3 REGION OF THE HIV-1 ENVELOPE GLYCOPROTEIN IN BRAZIL

Objective: To examine the genetic heterogeneity of the V3 region of HI V-1 gp120 from 22 Brazilian HIV-1 specimens. Design: Genetic heterogen eity was examined by DNA sequencing of the C2 V3 region of the HIV-1 e nvelope (env) gene from polymerase chain reaction (PCR)-amplified HIV- 1 DNA. Deduced amino-acid sequences were compared to determine the ext ent of amino-acid conservation among the Brazilian specimens. Genetic similarity among and between the Brazilian specimens and other previou sly published HIV-1 isolates was analyzed by principal co-ordinate and DNA parsimony methods.Methods: A 282 base pair (bp) region of a 1.5 k ilo (k) bp PCR-amplified HIV-1 env fragment was sequenced by a Taq dye -labeled primer cycle sequencing reaction. Nucleotide sequences were u sed to analyze inter-specimen relationships based on overall nucleotid e sequence similarity and DNA parsimony principles. Results: Amino-aci d comparison showed that 15 of the 35 (43%) residues of the V3 loop we re conserved among the Brazilian specimens. Nine of the 22 (40%) Brazi lian specimens contained the North American-European GPGR tetrapeptide motif, while eight (36%) contained the GWGR motif, previously reporte d in Japanese isolates. Principal co-ordinate analysis demonstrated th at 19 of the 20 examined Brazilian HIV-1 specimens were more similar t o North American and Haitian isolates than to African isolates. Simila r results were also obtained by DNA parsimony analysis. Conclusion: Th e majority of the Brazilian specimens examined are more genetically re lated to North American and Haitian HIV-1 isolates than to African iso lates. This finding and the presence of a GWGR V3 loop motif in some B razilian isolates may be important for vaccine development.