Molecular evidence for transmission of viruses: hepatitis B and C viruses and human immunodeficiency virus

Securing molecular evidence for transmission of RNA viruses is critically dependent on the time elapsed after infection. To establish HCV transmission by blood transfusions from specific donors, we deduced the sequence of amino acids 329 to 410 of HCV in 30 transfusion recipients and 120 of their blood donors. Phylogenetic analyses of hypervariable region 1 (HVR1) and genotyping furnished proof of transmission. Linear regression analysis showed no differences between HVR1 sequences from the recipient and the implicated donor up to 7.9 weeks post-transfusion, but donor and recipient sequences diverged subsequently (r=0.690). The choice of viral genomic region is also important. We compared four genomic regions in HIV-1 encoding variable regions V1, V2 and V3 in the env gene and p2 in the gag gene in documented cases of mother-to-infant HIV-1 transmission. The less variable regions of V3 and p2 provided positive evidence for virus transmission, in contrast to results obtained on highly variable regions V1 and V2 (p<0.05). Intrafamilial transmission of hepatitis B virus, a DNA virus, could be demonstrated on the molecular level by sequencing of a 100-nucleotide region of the viral genomes from 96 Chinese children and their parents. In 28 of the 30 mothers and 6 of 8 fathers, sequences were identical to those of their offspring (p<0.00005).