Application of Hepatitis B Virus (HBV) DNA Sequence Polymorphisms to the Study of HBV Transmission

Short sequencesin hypervariableregions of the hepatitis Bvirus (HBV)genome can beused to identify different strains, providing a novel approach to the study of HBV transmission. The nucleotide sequence in positions 2551–2650 (1: EcoRI site) was determined for serum HBV DNA from 96 Chinese children living in Hong Kong and from 38 of their parents. HBV DNA was extracted and sequenced after amplification with the polymerase chain reaction, using as primers oligonucleotides corresponding to two conserved sequences. Among 82 unrelated children, 32 HBV DNA variants were present. One sequence was present in 33 children and 31 variants were found among the other 49. Siblings within each of nine families had the same variant; in three families siblings had different variants. Six of the eight fathers and 28 of the 30 mothers had HBV DNA sequences identical to those of their offspring. A total of 34 variants were found among the 134 individuals. The hypothesis of random assortment of sequences in parents and children was rejected (P < .00005). Thus, this newapproach proves the occurrence of intrafamilial transmission of HBV among Chinese.