HIV type 1 non-B subtype prevalence in Spain, 1997-1998

We have evaluated the prevalence of HIV-1 non-B subtypes in Spain by means of an enzyme immunoassay (EIA) for discrimination between B and non-B subtypes. Samples were obtained from newly diagnosed patients attended at internal medicine outpatient clinics between October 1997 and October 1998. Discrimination between HIV-1 B and non-B subtypes was carried out by means of the EIA, with V3 synthetic peptides specific to the different subtypes. Non-B-serotyped samples were genetically analyzed in the gp41 region from the original sera. During the study period, 909 samples were collected from 21 medical units located in various Spanish geographical regions. Serotyping was possible in 885 cases, of which 791 were assigned as B serotype (89.38%), 70 showed no reactivity to any of the peptides (7.91%), and the remaining samples displayed other reaction patterns (2.72%). Of the 94 non-B-assigned samples, 65 were genetically characterized in the gp41 region of the env gene: 55 were B subtype, 5 were A subtype (4 clustered with CRF02AG reference strains), 3 were C subtype, and 2 were G subtype. The prevalence rate for non-B subtypes in Spain was established at 1.13% (95% CI, 0.59-2.21). Although the B subtype is predominant in the Spanish population, other subtypes have been detected.