The changing molecular epidemiology of HIV in the Philippines

The Philippines has one of the fastest-growing HIV epidemics in the world. Possible reasons for this include increased testing, increased local transmission, and possibly more aggressive strains of HIV. This study sought to determine whether local molecular subtypes of HIV have changed.

Viruses from 81 newly diagnosed, treatment-naive HIV patients were genotyped using protease and reverse transcriptase genes. Demographic characteristics and CD4 count data were collected.

The cohort had an average age of 29 years (range 19-51 years), CD4+ count of 255 cells/mm³ (range 2-744 cells/mm³), and self-reported acquisition time of 2.42 years (range 0.17-8.17 years). All were male, including 79 men who have sex with men (MSM). The genotype distribution was 77% CRF01_AE, 22% B, and 1% C. Previous data from 1985-2000 showed that most Philippine HIV infections were caused by subtype B (71%, n=100), followed by subtype CRF01_AE (20%). Comparison with the present cohort showed a significant shift in subtype (p<0.0001). Comparison between CRF01_AE and B showed a lower CD4+ count (230 vs. 350 cells/mm³, p=0.03). Survival data showed highly significant survival associated with antiretroviral (ARV) treatment (p<0.0001), but no significant difference in mortality or CD4 count increase on ARVs between subtypes.

The molecular epidemiology of HIV in the Philippines has changed, with the more aggressive CRF01_AE now being the predominant subtype.