High prevalence of HIV-1 subtype G and natural polymorphisms at the protease gene among HIV-infected immigrants in Madrid

Objectives Genetic characterization of HIV-1 subtypes among immigrants and natives infected overseas. Methods Phylogenetic analysis of HIV-1 protease sequences obtained from 109 foreigners (mainly Africans) and 32 native individuals infected overseas attending a reference HIV/AIDS centre located in Madrid, Spain. Results The overall rate of infection with HIV-1 non-B subtypes was 50.3% (71/141). Whereas 94.3% (67/71) belonged to immigrants (mostly Africans, 60/67), only 5.6% (4/71) were from native individuals (P < 0.05). The distribution of non-B subtypes was: 49 G, eight C, six A, four D, two F and two H. The high prevalence of subtype G was mainly related to individuals from west-central Africa. Interestingly, substitutions at three or more positions associated with protease inhibitor (PI) resistance were recognized in 52.6% of naive subjects carrying non-B subtypes, but only in 8% of those infected with B viruses (P < 0.05). The genotypes most frequently recognized among non-B and B subtypes occurred, respectively, at positions 36 (100 versus 12%), 20 (77.2 versus 0%), 63 (40.3 versus 64%), 82 (17.5 versus 0%), 10 (14 versus 12%), 77 (3.5 versus 34%), and 71 (0 versus 2%). Accordingly, changes 1-36 and 1-20 may be considered specific genetic markers for non-B, group M variants and subtype G infections, respectively. Conclusion Nearly two-thirds of foreigners with HIV-1 infection in Madrid carry non-B subtypes, subtype G (protease) being the most common among west-central African immigrants. The high rate of natural polymorphisms at the protease gene in non-B viruses may compromise the response to Pl. Therefore, HIV subtyping should be considered in treatment guidelines. (C) 2002 Lippincott Williams Wilkins.