A highly sensitive radioimmunoassay technique for subtyping the antibody to hepatitis B surface antigen.

A highly sensitive technique for determining the subtype specificity of antibody to hepatitis B surface antigen (anti-HBs) is described. Immunoadsorbent consisting of controlled pore glass coated with subtype specific HBsAg was used to remove homologous antibody from the test samples before testing them for residual antibody by a commercially available radioimmunoassay (RIA). A total of 73 anti-HBs-positive samples from asymptomatic blood donors were tested. In nearly 80% of these samples the subtype reactivity could be determined by this technique. Only 67% could be typed by conventional liquid phase absorption RIA and 22% by passive hemagglutination inhibition techniques. Among the samples with low anti-HBs titer, ad and ay subtypes were found with equal frequency; however, with the increase in anti-HBs titer, considerably higher proportion of ad specificity was detected.

Antibodies to delta antigen in asymptomatic hepatitis B surface antigen-reactive blood donors in the United States and their association with other markers of hepatitis B virus.

A total of 1,915 sera collected in 1979 from asymptomatic hepatitis B surface antigen (HBsAg) carriers were tested for delta antigen, antibody to delta antigen (anti-delta), hepatitis B e antigen (HBeAg) and antibody to hepatitis B e antigen (anti-HBe) in addition to HBsAg and its subtypes. These sera represented blood donated by volunteers to 49 of 57 regions of the American Red Cross located in nine geographic regions of the United States and Puerto Rico. A total of 72 (3.8%) sera had anti-delta activity while none had a detectable level of delta antigen. A significantly higher (p less than 0.01) prevalence of anti-delta (12.1%) was found in San Jose, California (Pacific Region); on the other hand, the East South Central region covering Alabama, Kentucky, Mississippi and Tennessee had a significantly lower (p less than 0.05) prevalence (1.4%) of anti-delta when compared with all other regions combined. Anti-delta was, however, detected in all regions of the United States and in Puerto Rico. The cause of significant differences in the prevalence of anti-delta was not clear. The distribution of anti-delta was not associated with age, sex or blood type of the donor. Sixty-nine of 70 samples with anti-delta were found among the 1,527 samples that had either HBeAg or anti-HBe. And among 149 that lacked both HBeAg and anti-HBe, only one sample had anti-delta. The difference is statistically significant (p less than 0.05). The presence of anti-delta was not associated with HBsAg/ad (2.7%) or HBsAg/ay (4.6%).

Hepatitis-associated markers in the American Red Cross volunteer blood donor population. ii. Distribution of level of HBsAg reactivity by radioimmunoassay and occurrence of nonspecific reactivity.

During the year 1978 this laboratory evaluated the specificity of all samples found reactive for hepatitis B surface antigen (HBsAg) by 44 of 57 regions of the American Red Cross Blood Services. Radioimmunoassay detected a total of 1.921 HBsAg-reactive sampled among more than three million donor units tested. A vast majority (96%) of the samples had high level of HBsAg (greater than or equal to 20 ng/ml). Only about 50% of the samples with low level of HBsAg (less than 20 ng/ml) were reactive in reversed passive hemagglutination. There were 13 samples that were repeatable for HBsAg but were considered nonspecific as they were nonneutralizable in radioimmunoassay, 2 donors who showed nonspecific reactivity were further tested and it was found that the reactivity in radioimmunoassay persisted for more than 9 months, and this reactivity was also detectable by a second commercial kit for HBsAg. Antibodies to core and surface antigen were not found in any of the nine samples that were tested. The explanation of this nonspecific reactivity is unclear, but the data suggest that the nonspecific factor(s) may be an inherent property of the sample rather than a deficiency of the test reagents.