High Frequency of HIV-1 Dual Infections Among HIV-Positive Individuals in Cameroon, West Central Africa

Objectives: To determine the frequency of dual inter- and intra-subtype HIV-1 infection among a cohort of 64 longitudinally-studied, HIV-1-positive individuals in Yaounde, Cameroon. Methods: Blood was collected every 3-6 months for up to 36 months and RNA was extracted from plasma. Gag fragment (HxB2 location 1577-2040) was amplified by nested RT-PCR, and mixed-time-point Heteroduplex Assays (HDAs) were performed. As heteroduplexes in this assay indicate >= 5% genetic discordance in the gag fragment, their presence reveals dual infection. Results were confirmed by phylogenetic analysis. Results: Heteroduplexes were generated by specimens of 10 Subjects (15.6%). Kaplan-Meier nonparametric estimate of maintenance of single infection was calculated; the rate/year of a 2(nd) infection was found to be similar to 11%. Dual infection was identified in the final specimens of five subjects, after as much as 18 months follow-up, while for the remaining five sub subjects, dual infection was identified in interim specimens within an average of 10 Months follow-up. Analysis of samples obtained after dual infection From each of the latter five subjects revealed two patterns: reversion to initial strain, or replacement of initial strain. Four subjects were dually-infected with HIV-1 strains of the same subtype, while 6 were infected with different subtypes. Conclusions: The high prevalence of recombinant HIV-1 strains in Cameroon may in part be explained by the high frequency of dual infection. In this genetically-diverse HIV-1 milieu, dual infections and the recombinant viruses they generate are strongly driving viral evolution, complicating vaccine strategies.