HIV disease progression: is the Brazilian variant subtype B' (GWGR motif) less pathogenic than US/European subtype B (GPGR)?

Background: The aim of this study was to investigate differences in HIV disease progression in patients infected with HIV subtype B with a GPGR motif in the V3 loop region (B-GPGR) versus the Brazilian subtype B variant with a GWGR motif (B'-GWGR).

Materials And Methods: Patients were enrolled in an ongoing cohort study at the University of São Paulo Dermatology Clinic in Sao Paulo, Brazil. V3 serology was performed by enzyme immunoassay with peptides representing two HIV subtype B strains, MN and SF2, and two Brazilian variant B'-GWGR strains. The incidence of AIDS-defining events was calculated, and Cox proportional hazards regression was used to estimate adjusted risk ratios.

Results: Of the samples from 114 patients studied, 23 (20%) were classified as B'-GWGR motif, and 91 (80%) as B-GPGR motif. Patients with T CD4+ cell counts less than 200 cells/mm3 or 200-400 cells/mm3 experienced an increased incidence of AIDS-defining events compared with patients who entered the cohort with T CD4+ cell counts greater than 400 cells/mm3. In a proportional hazard model including age, gender, T CD4+ cell count at entry into the cohort, and V3 serology, GWGR reactivity was associated with a decreased hazard rate for presenting an AIDS-defining condition during follow-up. Three patients in the group with GPGR serology died after experiencing an AIDS-defining event. None of the patients with GWGR serology died during follow-up.

Discussion: Survival analysis showed that patients infected with the Brazilian subtype B variant with a GWGR motif in the V3 loop had lower risk, adjusted for initial CD4+ cell count, of AIDS-defining events than patients infected with subtype B-GPGR strains.