Non-A, Non-B Epidemic Hepatitis: Visualization of Virus-like Particles in the Stool by Immune Electron Microscopy

SUMMARY Acute-phase stool samples collected from hepatitis cases during outbreaks of water- borne epidemic hepatitis were examined by immune electron microscopy (IEM). Spherical virus-like particles (27nm in diameter) were visualized in the stool of a hepatitis patient with serological evidence of non-A, non-B (NANB) hepatitis. The IEM demonstrated serological specificity of the antigen with the patient's own convalescent serum as well as a known pool of NANB hepatitis convalescent sera. It is suggested that these virus-like particles may be the aetiological agent of faeco-orally transmitted NANB epidemic hepatitis in India. Until recently, water-borne epidemics of hepatitis in India were believed to be due to the faeco-orally transmitted hepatitis A virus (HAV). Recent research has shown that the causative agent(s) of the disease is neither HAV nor hepatitis B virus (HBV) but a postulated new entity termed non-A, non-B (NANB) hepatitis (Khuroo, 1980; Wong et al., 1980). The identification of this form of hepatitis is mainly based on exclusion of HAV and HBV infection and clinico- epidemiological manifestation of the disease. Balayan et al. (1983) reported the isolation and visualization of virus-like particles from the stool of a volunteer after oral administration of a pooled faecal extract from NANB hepatitis patients. Since the sero-epidemiological studies on water-borne epidemic hepatitis in India indicated a possible excretion of the aetiological agent in the faeces, we examined the stool samples of hepatitis cases by immune electron microscopy (IEM). We report here the detection of 27-nm diameter, spherical virus-like particles in the stool of a patient with serological evidence of NANB hepatitis.