Japanese encephalitis virus, a mosquito-borne virus, can infect many species including swine and humans. While JEV is not currently in the US, incursion risk remains a concern given the virus’s recent global expansion. The presence of JEV in the US could have devastating outcomes for the swine industry because of its severe disease presentation in neonatal piglets and pregnant sows. In the event of an outbreak, accurate JEV diagnostics will be critical to disease monitoring. Currently, no approved diagnostic tests for JEV antibodies in swine exist in the US. As part of the Swine Health Information Center JEV Research Program, funded in collaboration with the Foundation for Food & Agriculture Research, a recently completed project led by Dr. Katharine Bossart, Integrated Research Associates, LLC, sought to build diagnostic testing capabilities for JEV in the US.
The main goal of the project was to build diagnostic capability for JEV based on diagnostic serological assays used and validated throughout Southeast Asia. JEV is classified as a biosafety level 3 agent, which limits the number of laboratories able to work with the virus and further reduces JEV diagnostic capability. Recognizing this, Dr. Bossart and team evaluated and developed JEV serology assays based on similar tests utilized overseas. These assays use nonhazardous recombinant JEV virus-like particles as viral antigens to broaden access and increase JEV testing capacity.
Read the industry summary for this study, #24-061, here.
JEV has been found throughout Asia and the Western Pacific with many of these countries having active surveillance programs in place for mosquitoes and swine. In countries outside of the region, including the US, JEV surveillance programs have not been implemented and vaccination is only advised in those traveling to countries where JEV is endemic. In 2022, a JEV genotype IV virus caused a widespread and devastating outbreak in eastern Australia in commercial piggeries and in humans. Currently, there are no approved diagnostics for JEV antibodies in humans or animals in the US. Initially, recombinant JEV virus-like particles (VLPs) were being made using a novel technology developed to explore their potential as JEV vaccine candidates. Expanding the use of recombinant JEV VLPs to replace inactivated JEV in diagnostic kits was a logical step towards not just building JEV diagnostic capability but also simplifying kit manufacturing.
To complete this study, sufficient quantities of inactivated JEV viral antigens, JE1, FE1, JN1, JN2 and FN1 monoclonal antibodies (mAbs) and corresponding mAb hybridomas, were imported from Venture Technologies. Stable cell lines expressing JEV VLPs from genotypes III, IV and V were used to produce recombinant JEV VLPs. Although recombinant JEV VLPs were made from genotypes III, IV and V, there were unique properties for each that were most notable for JEV V. Results indicated that JEV VLPs performed well and can replace inactivated JEV in diagnostic kits. Multiple genotypes of JEV can be included as antigens, which represents an improvement in design, and a scalable cGMP-compliant manufacturing process has been developed for recombinant JEV VLPs, which will simplify future regulatory filings and approvals.
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