Experimental infection of nonenveloped DNA virus (TTV) in Rhesus monkey

Virus fragments homologous to TTV were detected previously from an enterica lly transmitted outbreak of non-A-E hepatitis [Luo et al., 1999]. To test t he susceptibility of the Rhesus monkey to this virus and to establish its t ransmission routes, 6 Rhesus monkeys were inoculated, 3 orally and another 3 intravenously. The inoculum was prepared by extracting and filtering fece s collected from a patient during the incubation period identified in the d escribed outbreak. A second group of 3 monkeys was used for the passage stu dy. The feces and blood samples were collected for detection of the virus b y polymerase chain reaction (PCR). Four animals were subjected to liver bio psies and bile aspiration by open surgery for in situ virus detection. Vire mia occurred in 4-7 days after intravenous and 7-10 days after oral inocula tion. The virus was excreted in feces a few days after oral infection and s imultaneously with viremia after intravenous inoculation. The virus was als o detected in bile during the viremic phase. There was a prolonged carrier state with persistent viremia and virus excretion in feces for more than 6 months. Serum transaminase levels were not raised during the infection. The virus was present in both the cytoplasm and nuclei of hepatocytes, but no significant pathology was found. Therefore, the Rhesus monkey is susceptibl e to TT virus infection, but the virus seems nonpathogenic. Infection of th e liver may be established either by oral or parenteral inoculation. The vi rus may be released from liver into the blood or via bile into feces, so it may be transmitted by both blood and fecal routes. J. Med. Virol. 61:759-1 64, 2000. (C) 2000 Wiley-Liss, Inc.