Shedding of Japanese encephalitis virus in oral fluid of infected swine

Authors: LYONS, AMY - Kansas State University; HUANG, YAN-JANG - Kansas State University; PARK, SO LEE - Kansas State University; AYERS, VICTORIA - Kansas State University; HETTENBACH, SUSAN - Kansas State University; HIGGS, STEPHEN - Kansas State University; McVey, David; Noronha, Leela; HSU, WEI-WEN - Kansas State University; VANLANDINGHAM, DANA - Kansas State University

Submitted to: Vector-Borne and Zoonotic Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2018
Publication Date: 5/9/2018
Citation: Lyons, A., Huang, Y., Park, S., Ayers, V., Hettenbach, S., Higgs, S., Mcvey, D.S., Noronha, L.E., Hsu, W., Vanlandingham, D. 2018. Shedding of Japanese encephalitis virus in oral fluid of infected swine. Vector-Borne and Zoonotic Diseases. 10.1089/vbz.2018.2283.
DOI: https://doi.org/10.1089/vbz.2018.2283

Interpretive Summary: The high susceptibility and low infectious dose required for the establishment of Japanese encephalitis virus (JEV) infection following exposure via the oronasal route suggests that vector-free transmission of JEV may be epidemiologically important and warrants further investigation of the shedding profile of JEV in infected swine species. Additionally, this observation could enable the development of a non-invasive veterinary diagnostic method which targets the oronasal secretions. In this study, the feasibility of using pen-based collection of oral fluid as a surveillance method for the presence of JEV was demonstrated using experimentally challenged white-line crossbreed domestic pigs and SinclairTM miniature swine. Detection of JEV in oral fluid collected by this rope-based sampling method was achieved using three reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR) assays targeting the highly conserved genomic region of the nonstructural protein 5 (NS5) gene and the 3' untranslated region (UTR). Our results demonstrated the feasibility of using oral fluid samples for JEV surveillance and identified the appropriate primer sets for molecular diagnosis.

Technical Abstract: Japanese encephalitis virus (JEV) is a zoonotic mosquito-borne flavivirus endemic in the Asian-Pacific region. Maintenance of JEV in nature involves enzootic transmission by competent Culex mosquitoes among susceptible avian and swine species. Historically, JEV has been regarded as one of the most important arthropod-borne viruses in Southeast Asia. Oronasal shedding of JEV from infected amplification hosts was not recognized until the recent discovery of vector-free transmission of JEV among domestic pigs. In this study, oral shedding of JEV was characterized in domestic pigs used in commercial production and miniature swine representing the feral phenotype. A rope-based sampling method followed by the detection of viral RNA using reverse-transcriptase quantitative polymerase chain reaction allowed the collection and detection of JEV in oral fluid samples collected from intradermally challenged animals. The results suggest that the shedding of JEV in oral fluid can be readily detected by molecular diagnostic assays at the acute phase of infection. It also demonstrates the feasibility of this technique for the diagnosis and surveillance of JEV in swine species.