Detection of e Antigen during Acute and Chronic Hepatitis B Virus Infections in Chimpanzees

Abstract

Sera from 35 chimpanzees that developed infections with hepatitis B virus (HBV) were tested for the presence of hepatitis B e antigen (HB_e Ag) and its antibody (anti-HB_e). HB_e Ag was detected early in the course of the disease in the sera of six of eight chimpanzees, which became chronic carriers of hepatitis B surface antigen (HB₈ Ag), and in the sera of three of 27 chimpanzees, which recovered from acute infection with HBV. Of the nine chimpanzees with HB_e Ag, all had the previously described HB_e Ag/1 and HB_e Ag/2 specificities, and one appeared to have a third specificity. None of the 35 chimpanzees developed detectable titers of anti-Hb_e. Weekly samples of serum from four chimpanzees (three of which developed chronic HBV infections and one with an acute infection) were further studied to determine the pattern of acquisition of HB_e Ag. In each animal, HB_e Ag appeared eight to 12 weeks after the appearance of HB₈ Ag detected by radioimmunoassay and up to four weeks before elevation of levels of liver enzymes. In the three chronically infected chimpanzees, HB_e Ag was undetectable after four, nine, and 95 weeks, although HB_e Ag persisted. In the animal with acute hepatitis, HB_e Ag was undetectable before clearance of HB₈ Ag. The observed pattern of HB_e Ag detectability suggests that the appearance of HB_e Ag in the course of HBV infection in chimpanzees may signal the progression of the disease to chronic infection.