[Spontaneous hepatitis in the crab-eating macaque exposed to immunodepressants]

A case of spontaneous hepatitis was detected in experiments aimed at working out the conditions for reproduction of the immunosuppressed state in Macaca fascicularis with the purpose of subsequent infection of these monkeys with non A non B hepatitis virus transmitted by the fecal-oral route. One of 6 monkeys at the 8th day of the experiment was found to have developed an increase in the level of serum aminotransferases which grew progressively reaching high values by day 14. Fecal specimens from this monkey collected on the 5th day and later contained spherical virus-like structures 27 nm in diameter, antigenically identical with hepatitis A (HAV) virus. In the other 5 monkeys, no similar structures were found in fecal specimens throughout the experiment. The monkey with the signs of hepatitis was sacrificed on the 16th day of experiment, i. e. on the 8th day from the onset of hyperenzymemia. Immune electron microscopy of extracts of hepatic tissue and fecal specimens collected from this monkey has revealed 27 nm particles antigenically identical with HAV. The bulk of viral particles from the liver sedimented in cesium chloride buoyant density zone of 1.32 g/cm3, and from fecal specimens in the zone of 1.36 g/cm3. In the liver of this monkey, histological changes were found which are observed in acute hepatitis, and HAV antigen in hepatocyte cytoplasm was detected by the fluorescent antibody technique. It is suggested that the spontaneous disease of this monkey was due to natural infection with HAV which could be provoked by experimental immunosuppression.