Evidence has recently been accumulating toindicate that the e antigen system is a marker of the HBV infectivity. In this study, sera from 115 symptorn-free HBsAg carriers aged 1-85 years (male 55, female 60) were tested for e antigen and anti-e, and the results as given below Were obtained.
1. The e antigen was detected in 32 (28%) and anti-e in 35 (30%). The frequencies of e antigen and anti-e were observed in 5 age groups of 1-10, 1 1-20, 21-40, 41-60, and over 61 years. The positive rate of e antigen was 77% in the youngest group, and the rate fell stepwise by 41% in the 2nd and by 17% in the 3rd age group. In the 2 more older groups, however, the frequency scarcely changed as compared with that of the former group, respectively.
Although 42% of the all had neither e antigen nor anti-e, it is likely from the above results that all the HBsAg carriers are positive for e antigen in the beginning of the HBV carrier state, and, with advancing years of life, most of them become negative for e antigen and positive for anti-e, though there are wide differermces among the individuals in the age of the conversion of e antigen to anti-e. The decreasing prevalence of e antigen and increasing prevalenco of anti-e with age may be reflected in the difference in infectivity of young and old carriers; younger HBsAg carriers may be much more contagious than those in older age groups.
2. In family studies of the carriers, We have obtained a result that 10 out of the 11 offspring of 6 e antigen-positive mothers were HBsAg-positive. This suggests that HBV is vertically transmitted with an extremely high frequency when the carrier mother has e antigen.
Moreover, findings suggesting a father-to-child transmission were obtained, in which 3 out of the 6 offspring from 2 pairs of the e antigen-positive carrier father and HBsAg-negative mother, were HBsAg-positive. In one of the other families, 1 of the 3 children living with their grandfather with e antigen was positive for HBsAg, despite both the parents being HBsAgnegative. These results suggest that, even if the mother is HBsAg-negative, the infant is exposed with a considerably high frequency to the risk of becoming a long-term HBsAg carrier, when an e antigen-positive carrier exists among the family members.
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