Suspected epidemiological links between three cases of human immunodeficiency virus type 1 (HIV-1) infection were verified by the finding of a shared unique virus genotype. A probable male index case was not available for testing. Case 1 was a female sexual partner of the index case. Case 2 was an adult son of case 1. Case 3 was a female sexual partner of case 2. The link to the index case was substantiated by the subsequent finding of another female sexual contact of the index case, harboring the same HIV-1 genotype as the three other cases. To characterize the genotype further, the complete provirus nucleotide sequence was obtained directly from blood cell DNA of case 3. HIV cultivated from case 3 demonstrated CCR5 dependence, an extreme slow-low phenotype, and some genotypic features not present in its directly sequenced counterpart. Most of the gag, pol, and vif genes of these viruses clustered with one of the earliest African HIV-1 strains, MAL, previously classified as a recombinant between the subtypes A, D, and I. Most of the rest of the genome was related to subtype H, albeit with less than 90% identity in most regions. These viruses are the only ones shown to display extensive similarity with MAL in the gag-pol region and among the first HIV-1 recombinants described involving subtype H. We postulate that the gag-pol genes of MAL and these viruses are derived from a common ancestor that is not necessarily intersubtype recombinant in the pol region.
Three Norwegians, a couple and their daughter, died from AIDS in 1976 after up to 10 years of clinical manifestations of HIV infection (Lindboe et al., 1986, Acta Pathol. Microbiol, Immunol. Scand. 94, 117-123; Frøland et al., 1988, Lancet i, 1344-1345). We here demonstrate the presence of HIV DNA in autopsy materials from the father and the daughter. In phylogenetic analysis, the obtained sequences of the HIV pol and vif genes clustered with the HIV-1 group O clade. The genotyping was confirmed by detection of antibodies against HIV-1 group O in blood samples from the father and the mother. That these and other early isolates of HIV-1 are very similar to the presently circulating viruses and not intermediates between the present subtypes, verifies that the latest common ancestor of HIV-1 existed long before the emergence of the present epidemic. The presence of HIV-1 group O 30 years ago suggests that the limited spread of these viruses, compared to HIV-1 group M viruses, is not due to a later emergence of the group O viruses.