Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/1999
Publication Date: N/A
Citation: N/A Interpretive Summary: Channel catfish are susceptible to a virus disease that causes severe blood loss to the intestine and death in a high percentage of fish infected. The source of infection has not been understood because, except during an active outbreak of the disease, no trace of the virus could be found. This study describes the results of application of new DNA technology to identify the virus DNA in tissues of fish that were infected and recovered from the disease. These fish show no signs of having the disease, yet are thought to be able to transmit the disease to other fish (called latent carriers). Standard procedures for isolating the virus are not adequate to identify latent carriers. The techniques described here allowed identification of virus DNA in several organs and in blood cells of latent carriers. This study confirms that this virus establishes a latent infection in channel catfish.
Technical Abstract: Channel catfish virus (CCV) disease is an acute haemorrhagic disease in juvenile channel catfish (Ictalurus punctatus). While fish that survive primary CCV infection are suspected of being carriers of CCV, little is known concerning CCV tatency. In this report, fingerling catfish were infected with CCV by experimental immersion challenge. Infected fish displayed clinincal signs of CCV disease, but 22% of infected fish survived the acute disease. At 140 days post-infection, PCR analysis detected CCV DNA in the blood, brain, intestines, kidney, liver and peripheral blood leukocytes of latently infected fish. Further analysis indicated the cCV genome may exist as circular or concatemeric DNA during virus latency. This study, employing and experimental model of CCV disease, confirms that CCV establishes a latent infection of channel catfish.