Background: The wide genetic variability of HIV-1 isolates has allowed to classify them into several subtypes. Very high divergent strains have been isolated recently from West Africa patients with AIDS, and they have been called HIV-1 group O ("outlier").
Patients and methods: In April 1995 a couple of patients was referred for medical follow-up and definitive diagnosis of HIV-1 infection. Both were white and had been born in Spain. The husband had been working for 10 years in West Africa. CD4+ T-cell counts were below 250 x 10(6)/l in both subjects, and the wife had developed seborrheic dermatitis and mild pancytopenia. Serologic and genetic studies were performed to study the presence of HIV-1 group O infection in this couple.
Results: Serological tests (enzyme immunoassays, Western blot, line immunoassay) yielded indeterminate results for HIV-1 testing serum from the wife, but the husband's specimen was positive. Serological test for HIV-2 were negative in both subjects. In contrast, a new test allowed recognition of specific antibodies to HIV-1 group O in these patients. Furthermore, this infection was confirmed using a discriminative PCR methodology, which demonstrated the presence of specific HIV-1 group O sequences and the absence of group M sequences.
Conclusions: The first two cases of HIV-1 group O infection in Spain are described. It is pointed that diagnostic tests and therapeutic strategies need to considers the presence of this new HIV variant outside endemic areas.