Evidence that non-B strains of HIV being transmitted in the UK

Doctors in south London have obtained the first evidence to show that non-B subtypes of HIV are being transmitted in the United Kingdom. In a study published in the February 2^nd edition of the Journal of Acquired Immune Deficiency Syndromes, the investigators found evidence of onward transmission of non-B subtypes of HIV amongst Africans, UK born whites and Caribbeans.

In recent years there has been a significant increase in the number of heterosexual HIV infections in the UK. Nearly all these new infections are due to migration from countries with a high HIV prevalence in southern Africa. This migration has lead to an increase in the amount of non-B subtype HIV in the UK.

Previously, there was no evidence of onward transmission of non-B subtype HIV in the UK and investigators at King’s College Hospital wished to determine the genetic diversity of HIV and establish the source of non-B subtype infections in their ethnically mixed south London population.

Between May 1999 and May 2000 blood samples from 344 patients were sequenced to determine the subtype of HIV an individual was infected with. Patients’ medical records were also reviewed to obtain their demographic details and likely source of infection with HIV.

A total of 223 patients were infected with a non-B subtype including 97% of Africans, 31% of Caribbeans and 14% of white patients.

A total of 17 Africans were thought to have been infected with a non-B subtype in the UK, including three vertically infected children. The remaining 14 patients were heterosexual men and women, four of whom were born in the UK. Seven of the African-born patients had had a previous negative HIV test, and three of the African-born patients had sexual partners from southern Africa after their arrival in the UK.

Of the 21 white patients with non-B subtype HIV, 13 were gay men, three were heterosexual women, three were heterosexual men and two were injecting drug users. The investigators determined that 15 of these patients were probably infected with non-B subtype in the UK, including all three heterosexual women, one of the heterosexual men, both of the drug users and nine of the gay men.

There were 13 Caribbean patients with non-B subtype, eight of whom were born in the UK and five in Jamaica. The investigators determined that all 13 infections were acquired in the UK.

The investigators also found that diversity in the types of non-B HIV present in their patients, with subtypes A, C, D as well as recombinant and “mosaic” forms of the virus.

“Our findings represent the first documented evidence using molecular and epidemiological data for onward transmission of non-B HIV-1 strains in the UK”, write the investigators. They add, “with increasing migration and international travel, the diversity of HIV-1 subtypes in Western Europe and the potential for onward second-generation transmission should continue to increase.”