Early stages of rabbit haemorrhagic disease virus infection monitored by polymerase chain reaction

In order to define more accurately the initial events that take place during rabbit haemorrhagic disease virus (RHDV) infection, different organs of experimentally infected rabbits were analysed for the presence of the virus and correlated with histopathological observations. A total of 24 rabbits were intranasally inoculated with a viral suspension, and tissue samples were taken from the liver, spleen, kidney, lung, thymus, lymph node and tonsil at different intervals post-inoculation (2, 4, 6, 12, 18, 24, 30, 36, 48, 50, 51, 70 and 72 h). Histopathological observations revealed the presence of the first significant lesions at 30 h post-inoculation (p.i.) in the liver. Using an ELISA and a haemagglutination test (HAT), the virus was detected in the liver at 36 h p.i. The reverse transcriptase-polymerase chain reaction (RT-PCR) showed that the RHDV RNA was present as early as 18 h p.i. in the liver acid spleen, whereas thymus, kidney, tonsil and lymph node were found to be positive after more than 36 h p.i. The lungs presented a variable positivity between 0 and 36 h p.i., but remained positive after this time.