Serial Fecal-oral Transmission of Hepatitis A Virus (HAV) in Marmosets (Saguinus labiatus) : Establishment of an Experimental Model for a Natural Transmission Pathway of HAV

Hepatitis A virus (HAV) originally obtained from stool specimens of a human patient with an acute phase of hepatitis type A was successively passaged in marmosets, Saguinus labiatus, by oral administrations. The pattern of infection was as follows: after a certain incubation period, the appearance of HAV antigen in stools was the first sign of infection, followed by the simultaneous elevations of transaminases and anti-HAV antibody with approximately 10-day intervals. This sequence was consistently observed throughout four successive passages. More passages resulted in less incubation time: the incubation period at passage 3 was 49 and 35 days in two animals, and those at passage 4 and 5 were 26 and 21 days, respectively. Because the inoculation dosis used beyond passage 2 was adjusted at 2,000 antigen units, the shorter incubation period in later passages suggested the adaptation of HAV in marmosets, Saguinus labiatus. Since the adapted virus showed reproducible incubation periods as well as clinical courses in marmosets, it is now possible to look for the primary target organs other than the liver of HAV, if any, and to use this system for the screening of vaccine candidates