Intragastric infection induced in marmosets (Callithrix jacchus) by a Brazilian hepatitis A virus (HAF-203)

RESUMO

Several specied of non-human primates have been used in studies on experimental infection with hepatitis A virus (HAV). Attempts to infect a South-American marmoset (Callithrix jacchus) with a Brazilian HAV isolate (HAF-203) are described here. Four seronegative animals were inoculated intragastrically and one was sacrificed on day 11,20,47 and 62 after infection. One uninfected animal was included as control. Liver, small intestine, lymph node, spleen and kidney samples were collected for histological diagnosis and immunocytochemistry studies. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) serum enzymes and anti-HAV antibodies were monitored by a colorimetric procedure (Abbott) and an enzyme immunoassay (ELISA), respectively. Feces were collected daily for HAV antigen (HAVAg) detection by ELISA. Increased levels of HAVAg were detected in hepatocytes 11 days after infection, with a gradual decrease during the course of infection. Shedding of HAVAg in feces was observed from the late incubation to the early acute phase (20th day to 47th day after infection). The end of the incubation period was indicated by the initial increases in serum ALT and AST. Severe hepatic lesions such as piecemeal necrosis and bridging necrosis were detected during the acute phase, coinciding with the maximum transaminase levels and the appearance of anti-HAV antibodies. On the 62nd day (convalescent phase), the hepatic tissue showed evidence of regeneration and the transaminase values had returned to baselines. The serological, biochemical, antigenic and histological evidence of hepatitis A was similar to that observed in several primate models inoculated with other HAV isolates. The data suggest that C. jacchus can be a valuable model for the study of hepatitis A and for the evaluation of HAV vaccines