ELUCIDATION OF AN HIV-1 TRANSMISSION FROM MOTHER-TO-CHILD IN WEST-AFRICA BY SEQUENCE-ANALYSIS

A pregnant woman living in Germany went to Ghana for several months, w here she received 4 blood transfusions. Her newborn child also receive d one blood transfusion in West Africa. After return to Germany, HIV-1 infection was detected in both of them. Serotyping with V3 peptides r evealed that the sera reacted only poorly with the subtype B-specific antigens. To investigate whether the child had been infected by vertic al or parenteral transmission, we amplified different proviral HIV-1 g ene segments from samples obtained 1-3 years after infection. Sequence analysis of the hypervariable regions V1 and V2 of the proviral env g ene was misleading, since the viral population of the mother was highl y heterogeneous, whereas only one predominant viral variant was found in the child. In contrast, sequences of the gag p17 gene and the regul atory genes nef and vif were homogeneous and revealed a very high homo logy, suggesting that the child had been infected by the mother. This was confirmed by phylogenetic tree analysis showing that sequences of mother and child clustered together and that both were infected by HIV -1 subtype A which is common in West Africa. The results suggest that sequence analysis of the hypervariable regions V1 and V2 alone can lea d to unclear results, especially if not single genomes are analysed bu t a mixture of quasi-species. It is recommended that investigations in to HN transmission should be based on sequence analysis of several HIV genes.