Background: Human immunodeficiency virus (HIV)-1 strains are divided into seven genetic subtypes based on their gag sequences (A, B, C, D, F, G and H). Strains that have appeared in Finland show unusual heterogeneity compared to most industrialized countries, up to 25% of the strains belong to non-B subtypes (Liitsola et al., 1996). Three D subtype viruses have so far been identified in Finland. All patients were men, one Kenyan immigrant and two Finnish men, who had been infected in Africa. Here we describe some of the characteristics of the genomic diversity of these strains.
Method: The genotype was determined by direct solid-phase sequencing of the p7 gag region. Phylogenetic analysis was done using standard methods.
Results: The analysis showed that the D subtype sequences clustered clearly distinctly from the other non-B strains, but did not suggest any transmission links between the three cases. From one case both cerebrospinal fluid (CSF) and blood leukocyte virus isolates were studied. The analysis revealed significant differences between the blood and CSF viruses. A four amino acid duplication and other differences were observed between the strains.
Conclusion: The results confirm that D subtype viruses do indeed occur in Finland and they represent quite heterogenic strains within the D cluster.