Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 24, 2014
Publication Date: March 26, 2014
Citation: Buehler, J., Lager, K., Vincent, A., Miller, C., Thacker, E., Janke, B. 2014. Issues encountered in development of enzyme-linked immunosorbent assay for use in detecting influenza A virus subtype H5N1 exposure in swine. Journal of Veterinary Diagnostic Investigation. 26(2):277-281. Interpretive Summary: The emergence of the H5N1 highly pathogenic avian influenza virus in the late 1990s that could infect humans changed the public perception of animal influenza. The first human H5N1 virus infections were identified in Hong Kong and associated with contact with H5N1 infected poultry. During the intervening years this virus spread to many regions in the Eastern Hemisphere by the movement of infected wild birds and poultry resulting in over 600 human infections of which over half have died. In addition to the great concern over poultry serving as reservoir for H5N1 virus, the potential role of swine as a mammalian reservoir has been raised. Swine can serve as a mixing vessel in which human, avian, and swine influenza viruses can mix resulting in the production of novel viruses that can infect man and animals. Potentially, this could happen with the avian H5N1 virus. This possibility led to the development of diagnostic assays that can detect H5N1 virus in swine and differentiate this virus from common swine influenza viruses. There is limited work on diagnostic tests that can detect H5N1-specific antibody in swine. In the study reported here, it was shown that one antibody detection method, the hemagglutination assay, was limited in its ability to quickly detect H5N1 antibody and have broad application. A different type of method, an ELISA test, was developed that could be used for higher capacity testing and was more broad in detecting antibody to different H5N1 viruses. Results indicate the ELISA method has potential for use as a blood test to screen pig serum for H5N1 antibodies which could be used if H5N1 influenza viruses become established in swine.
Technical Abstract: A potential mechanism by which highly pathogenic avian influenza H5N1 viruses could become established in humans is through the infection of and adaptation in pigs. To detect the occurrence of such adaptation, monitoring of the pig populations in endemic H5N1 areas through serological screening would be highly desirable. In the current study, it was determined that hemagglutination inhibition assays would have limited ability to detect antibodies against H5N1 developed in pigs, primarily because the use of multiple virus strains would be required. Whole recombinant virus and recombinant hemagglutinin antigen enzyme-linked immunosorbent assays (ELISAs) were developed for detection of antibody against multiple H5N1 strains and determined that the recombinant hemagglutinin antigen-based ELISA proved to be more sensitive than the whole virus antigen ELISA assays for the virus strains used in this study. These results provide important information and considerations for the development of serological screening assays for highly pathogenic avian influenza H5N1 viruses.