Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2009
Publication Date: 5/20/2010
Citation: McClenahan, S.D., Bok, K., Sosnovtsev, S.V., Neill, J.D., Burek, K.A., Beckmen, K.B., Green, K.Y., Romero, C.H. 2010. Expression and Self-Assembly of Virus-Like Particles from Two Genotypes of Marine Vesiviruses and Development of an ELISA for the Detection of Antibodies. Veterinary Microbiology. 142(3-4):184-192. Interpretive Summary: Emerging or newly discovered viruses are becoming more of a threat to both human and animal health. Some of these viruses belong to the calicivirus family of viruses. There is a group of caliciviruses that can cause disease in many different species of mammals, called the San Miguel sea lion viruses (SMSV). These viruses are closely related to the exotic caliciviruses that cause a very severe disease of pigs called vesicular exanthema of swine. Both groups collectively are termed vesiviruses. There is evidence that many different species of marine mammals may serve as reservoirs for these viruses to enter into domestic livestock herds. In response to this, a novel enyme-linked immunosorbant assay (ELISA) test was developed that was able to detect very low levels of antibodies against these viruses in serum from infected animals. This test successfully detected antibodies directed against 21 different vesivirus strains. The ELISA was used to screen for the presence of vesivirus specific antibodies in the sera of free-ranging marine mammals. The ELISA results demonstrated that marine mammals that inhabit the Pacific Ocean waters of southeast Alaska are widely exposed to antigenically related marine vesiviruses, while no previous exposure could be demonstrated in 17 Steller sea lions from the Aleutian Islands. This new test will be especially valuable when large numbers of clinical samples are screened as in the case of surveillance for these viruses.
Technical Abstract: Sequences encoding the major capsid protein (VP1) from two marine vesivirus isolates (Steller sea lion viruses V810 and V1415) were engineered for expression of virus-like particles (VLPs) in the baculovirus system. The resulting VLPs were morphologically similar to native vesivirus virions. Purified VLPs were probed in immunoblots with antiserum specific for San Miguel sea lion virus (SMSV), and a predominant protein of approximately 60 kDa was detected. An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies was developed in which the VLPs served as antigen. The VLPs were adsorbed to the wells of a microplate, and the specificity of the ELISA was established with hyperimmune sera raised against other caliciviruses, including SMSV. The ELISA was used to screen for the presence of vesivirus specific antibodies in the sera of free-ranging marine mammals. The ELISA results demonstrated that marine mammals that inhabit the Pacific Ocean waters of southeast Alaska are widely exposed to antigenically related marine vesiviruses, while no previous exposure could be demonstrated in 17 Steller sea lions from the Aleutian Islands. The broad reactivity of these VLPs and their non-infectious nature will facilitate sero-epidemiological studies aimed at determining prevalence and incidence of marine vesiviruses in mammals that inhabit both the Pacific and Atlantic oceans.