Evolution of human immunodeficiency virus subtype A in women seroconverting post partum and in their offspring post-natally infected by ingestion of breast milk.
An evolutionary analysis was undertaken of HIV-1 gag p17 sequences taken from a small cohort of hemophilia B patients infected from a common batch of clotting factor concentrate. The sequence population found at seroconversion was highly homogeneous, suggesting that the infecting batch also contained little sequence variation. Genetic diversification was found in follow-up sequences taken approximately 3 years later and was generally found to be complex. Greater rates of synonymous to nonsynonymous substitution were observed, especially when comparing distantly related isolates, and the rate of synonymous substitution was used to estimate times of divergence for a number of isolates of HIV-1 including the origin of the subtypes A to H. The p17 region is therefore proposed as a useful marker for future epidemiological studies.