Re-analysis of human immunodeficiency virus type 1 isolates from Cyprus and Greece, initially designated 'subtype I', reveals a unique complex A/G/H/K/? mosaic pattern.

Human immunodeficiency virus type 1 (HIV-1) has been classified into three main groups and 11 distinct subtypes. Moreover, several circulating recombinant forms (CRFs) of HIV-1 have been recently documented to have spread widely causing extensive HIV-1 epidemics. A subtype, initially designated I (CRF04_cpx), was documented in Cyprus and Greece and was found to comprise regions of sequence derived from subtypes A and G as well as regions of unclassified sequence. Re-analysis of the three full-length CRF04_cpx sequences that were available revealed a mosaic genomic organization of unique complexity comprising regions of sequence from at least five distinct subtypes, A, G, H, K and unclassified regions. These strains account for approximately 2% of the total HIV-1-infected population in Greece, thus providing evidence of the great capability of HIV-1 to recombine and produce highly divergent strains which can be spread successfully through different infection routes.