Edna Ben-Porath

A hepatitis B virus mutant associated with an epidemic of fulminant hepatitis

BACKGROUND A nosocomial outbreak of fulminant hepatitis B occurred in five patients in Haifa, Israel. Previous investigations identified the suspected source as a carrier of hepatitis B surface antigen who was positive for antibodies to hepatitis B e antigen and had chronic liver disease. We examined the strain of hepatitis B virus (HBV) that caused this epidemic, in order to identify specific mutations in the precore or core region. METHODS The presence of HBV was identified by polymerase-chain-reaction amplification of viral DNA in serum from the source patient, the five patients with fulminant hepatitis B, and five controls with acute, self-limited hepatitis B. The amplified viral HBV DNA samples were then cloned and sequenced. RESULTS Sequence analysis of viral DNA established that the same HBV mutant with two mutations in the precore region was present in the source patient and the five patients with fulminant hepatic failure. This HBV mutant had significant sequence divergence from other known HBV subtypes in the X, precore, and core regions. Cloned HBV DNA derived from a hospitalized patient who had subclinical hepatitis B at the same time as the outbreak and from four other control subjects with acute, self-limited hepatitis B all contained the wild-type sequence in the precore region. CONCLUSIONS In the outbreak we studied, a mutant hepatitis B viral strain was transmitted from a common source to five patients who subsequently died of fulminant hepatitis B infection. Naturally occurring viral mutations hepatitis B infection. Naturally occurring viral mutations in the HBV genome may predispose the infected host to more severe liver injury.

Improved detection of hepatitis B surface antigen (HBsAg) in blood donors by monoclonal radioimmunoassay.

We evaluated the performance of a monoclonal radioimmunoassay (M‐RIA) with enhanced sensitivity and high specificity for hepatitis B surface antigen (HBsAg) in blood donors. The results were compared to a conventional RIA that used polyvalent antibodies (P‐RIA). Analysis of 6409 American blood donors not reactive by P‐RIA revealed an additional 1.4 HBsAg‐positive donors per 1000 by M‐RIA, or an approximate 60 percent, improvement in HBsAg detection rate. Furthermore, in 995 Israeli blood donors negative by P‐RIA, 11 additional HbsAg‐positive donors were identified. The 55 percent improvement in detection rate was similar to that observed with American blood donors. Since several of the newly identified HBsAg‐positive blood donors had antibodies to the core antigen (anti‐HBc) as the only serologic evidence of recent or past hepatitis B exposure, we studied an additional 68 anti‐HBc‐ positive individuals with the M‐RIA. It was found that 26 percent (18/68) reacted only by M‐RIA and not by P‐RIA. These findings suggest that there are blood donors with HBsAg undetectable by P‐RIA.

Correlation of HBV DNA and monoclonal reactivity to HBsAg in serum of patients with HBV infection

Hepatitis B virus (HBV) DNA hybridization assay, a monoclonal radioimmunoassay (M-RIA) for hepatitis B surface antigen (HBsAg) and conventional polyclonal immunoassays for HBV associated antigens were used to study sera from patients on dialysis and with acute hepatitis B. HBV DNA was detectable in hepatitis B e antigen (HBeAg) negative patients with acute hepatitis but not in HBsAg+ HBeAg- dialysis patients. In acute hepatitis, HBsAg immunoreactivity by M-RIA could still be detected even though a commercial immunoassay for HBsAg, the AUSRIA II, and the HBV DNA assay were no longer positive. Unlike in acute HBV infection, serum HBV DNA was detectable in dialysis patients who were AUSTRIA II negative but M-RIA positive. Serial determination of HBsAg by M-RIA and HBV DNA revealed episodes of HBV DNA positivity months after both the HBsAg was no longer positive by polyclonal immunoassay. Thus, the M-RIA for HBsAg and the molecular hybridization technique for HBV DNA are sensitive and specific assays for the identification of potentially infectious individuals who would not have been characterized as such based on the results of conventional polyclonal immunoassays.