Virulent HIV Strain Emerges In UK

A strain of HIV that is endemic in Asia but rare in the west has now gained a toehold in the UK, sparking off fears that it could lead to an increase in the rate of heterosexual transmission. HIV subtype E is endemic in Asia where most HIV-positives are heterosexual; in the West, where the majority of cases are homosexual men, subtype B is far more common.

In The Lancet of May 25, researchers from the UK's Public Health Laboratory Service, in Colindale, North London, reported the results of an HIV-1 genetic subtyping study in 93 patients. This study, which looked at the genomes of the viruses with respect to the env and gag sequences, found that apart from subtype B, a range of strains were encountered, including A, C, D and G, as well as mosaics of D/A, E/A and G/A. Mosaics occur as a result of the formation of recombinant viruses with genetic material from two separate strains.

More recently, the PHLS researchers, headed by John Clewely, say they have identified a group of 72 HIV-positive men and women infected with subtype E, most of whom are thought to have contracted the infection as a result of having heterosexual contact in Thailand or from partners who have. They also note that the incidence of heterosexual HIV is around 19% amongst the infected population in the UK, and that around 75% of these are as a result of exposure to the virus outside the UK.