[Human immunodeficiency virus type 1 subtypes in cohort of infected patients, Saint-Etienne, France, from 1984 to 2003].

Objective: The authors had for aim to study the distribution of HIV-1 subtypes in a cohort of HIV-1 positive patients in the University hospital of Saint-Etienne, France, and to describe the epidemiological characteristics of patients infected with a non-B subtype strain.
Design: An epidemiological study was made on 271 HIV-1 positive patients followed up in the Infectious Diseases Department over 20 years. All patients sample were subtyped by serotyping and some samples were also tested by genotyping.
Results: Two hundred and sixty-four patients (191 men and 73 women) were found infected by an HIV-1 strain belonging to the M group. After combining serotyping and genotyping results, 195 patients were found infected by a B subtype and 69 by a non-B subtype. Most of the latter strains belonged to an A subtype or related ones. The following factors were shown to be linked to an infection by a non-B strain: being born abroad, having contracted the infection though heterosexual practice, and being a woman. The incidence of non-B strains increased regularly over time (to reach more than 40% in 2003). This progression was especially noted for men born in France with risky sexual behaviour.
Conclusion: These results indicate that more than 40% of HIV-1 new cases detected in the Saint-Etienne area are related to non-B strains and that strains of A and related subtypes are common in the local population with risky sexual behaviour.