Analysis of HIV-1 sequences vertically transmitted to infants in Kisumu, Kenya

HIV-1 prevalence in Kenya among women aged between 15-19 years is approximately 23%. These women are prospective mothers and therefore can play an important role in mother-to-child transmission of HIV. The risk of a seropositve mother transmitting the virus to her infant is 25-35% in developing countries, such as Kenya, where antiretroviral drugs are not readily available.

This study was undertaken to evaluate the molecular nature of HIV-1 strains, assess recombination and it's relevance in mother-to-child transmission in Kenya.

HIV-1 gag and gp120 sequences were derived from peripheral blood mononuclear cells (PBMC) of 16 infected mothers and infants, from Kisumu, Kenya. PCR, cloning, and phylogenetic analyses were conducted to examine any sequence differences between HIV-1 strains derived from mother-infant pairs.

The cohort consisted of seven pairs harboring possible subtype A/D recombinants, eight pairs with apparent pure A or D strains and one possible dual infection. This dual infection comprised of a pure subtype A region and an A/D recombinant, and was detected in one of the mother's sample. Interestingly, only the recombinant virus was detected in the paired baby sample.

This study shows that HIV-1 inter-subtype recombinants can be effectively transmitted vertically to infants, and could possibly be favored in this setting where multiple subtypes infect women. Together, dual infections and the co-existence of multiple HIV-1 subtypes is encouraging the emergence of recombinant HIV strains and their rapid dispersal.