A New Genetic Subtype of HIV-1

During a large screening of Swedish individuals presumed to be infected by subtypes other than the common B subtype (unpublished material), two unrelated individuals were found to carry virus of a previously unknown HIV-1 subtype. Blood samples were collected in Sweden from two HIV-1 infected immigrants from Zaire. Sample SE7022 was obtained in December 1993 from a female who was asymptomatic but had low CD4+ lymphocyte counts (184 × 10 cells/l). The first HIV-antibody positive sample from this female was obtained in May 1990, however the epidemiological investigation indicated that she became infected in Zaire between 1981 and 1986. Sample SE7887 was obtained in October 1994 from a man, who was found HIV-antibody positive in August 1994 (he had tested negative in Sweden in January 1993). His CD4+ lymphocyte count was normal (567 × 10 cells/l). Both patients were heterosexual. A thorough epidemiological investigation, including contact tracing, did not reveal any direct contact between the two individuals.