Molecular Epidemiology of HIV-1 Infection in the Philippines, 1985 to 1997: Transmission of Subtypes B and E and Potential Emergence of Subtypes C and F

Abstract

The molecular epidemiology of HIV-1 infection in the Philippines from 1985 to 1997 was investigated following subtyping of 54 (33 women, 21 men) prospectively collected clinical specimens using the heteroduplex mobility assay (HMA). In contrast with other Asian countries, subtype B accounted for most (70%) of the infections in the population studied, among female commercial sex workers (CSWs, 18 of 28), overseas contract workers (OCWs, 7 of 10), and men who have sex with men (MSM, 8 of 10). However, although viral specimens from HIV-seropositive persons diagnosed before 1993 (n = 16) were all of subtype B, diagnoses in more recent years (1993-present, n = 38) indicate the existence of subtypes E (29%), F (8%), and C (5%) in the population. Since its estimated introduction in the early 1990s, subtype E has accounted for 60% of the infections among female CSWs diagnosed after 1992 (n = 15). This genotype distribution shift occurred in parallel with a shift in transmission focus from the U.S. military bases to the the Philippine national capital region. So far, both events appear to have had no significant effect on the stability of HIV-1 transmission in the country. The recent identification of non-B subtypes in the Philippines may present novel insights on the dynamics of HIV-1 transmission in a high-risk but low-HIV prevalence setting in Asia.

Comparing the Ex Vivo Fitness of CCR5-Tropic Human Immunodeficiency Virus Type 1 Isolates of Subtypes B and C

“…Introductions of subtype C into these regions may be a founder event, but other subtypes did preexist in some populations (e.g., A and B in southern Africa and India) (40 The rapid insurgence of subtype C throughout the world suggests that this clade may be fitter within the population. It is also quite conceivable that a subtype such as C may be introduced into human subpopulations with different social and sexual mixing patterns than populations infected by another subtype(s) (32,51,72). Thus, subtype C may not be in direct competition with other subtypes in these geographical regions.…”

The changing molecular epidemiology of HIV in the Philippines

“…Group M subtypes B, C, D, and F have been seen in the Philippines, along with the circulating recombinant form (CRF) CRF01_AE (Paladin et al, 1998;Gloriani-Barzaga et al, 1998;Espantaleon et al, 2003;Santiago et al, 1998). Two early studies in 1998 found that the majority of HIV infections were caused by subtypes B and CRF01_AE, with low numbers of subtypes A, C, D, and F (Paladin et al, 1998;Gloriani-Barzaga et al, 1998).…”

Rapid spread of hepatitis C virus among injecting-drug users in the Philippines: Implications for HIV epidemics

“…However, wide-range HIV strains have already been introduced in the country, i.e. ; five HIV-1 subtypes (A, B, C, D, F), a circulating recombinant form (CRF01_AE) Paladin et al, 1998;Santiago et al, 1998], a recombinant strain (gag-A/env-B) . Even HIV-2 ] have been identified.…”

“…Even HIV-2 ] have been identified. Among these, HIV-1 subtype B was the most predominant, followed by CRF01_AE [Paladin et al, 1998;Santiago et al, 1998;Espantaleon et al, 2003] and others [Ruxrungtham et al, 2004] have implied that the Asian AIDS epidemic may start among injecting drug users with secondary new infections being evident among sex workers. This is reasonable when considering the fact that the probability of HIV infection is 10-fold higher for the transmission through 5 contaminated needle sharing than that through sexual contact [Royce et al, 1997].…”