Genetic heterogeneity of the V3 region of the HIV-1 envelope glycoprotein in Brazil. Brazilian Collaborative AIDS Research Group.

OBJECTIVE

To examine the genetic heterogeneity of the V3 region of HIV-1 gp120 from 22 Brazilian HIV-1 specimens.

DESIGN

Genetic heterogeneity was examined by DNA sequencing of the C2 V3 region of the HIV-1 envelope (env) gene from polymerase chain reaction (PCR)-amplified HIV-1 DNA. Deduced amino-acid sequences were compared to determine the extent of amino-acid conservation among the Brazilian specimens. Genetic similarity among and between the Brazilian specimens and other previously 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 kilo (k) bp PCR-amplified HIV-1 env fragment was sequenced by a Taq dye-labeled primer cycle sequencing reaction. Nucleotide sequences were used to analyze inter-specimen relationships based on overall nucleotide sequence similarity and DNA parsimony principles.

RESULTS

Amino-acid comparison showed that 15 of the 35 (43%) residues of the V3 loop were conserved among the Brazilian specimens. Nine of the 22 (40%) Brazilian specimens contained the North American-European GPGR tetrapeptide motif, while eight (36%) contained the GWGR motif, previously reported in Japanese isolates. Principal co-ordinate analysis demonstrated that 19 of the 20 examined Brazilian HIV-1 specimens were more similar to North American and Haitian isolates than to African isolates. Similar results were also obtained by DNA parsimony analysis.

CONCLUSION

The majority of the Brazilian specimens examined are more genetically related to North American and Haitian HIV-1 isolates than to African isolates. This finding and the presence of a GWGR V3 loop motif in some Brazilian isolates may be important for vaccine development.