Characterizing the fecal shedding of swine infected with Japanese encephalitis virus

Abstract

Japanese encephalitis virus (JEV) is an enveloped, single-stranded, positive sense Flavivirus with five circulating genotypes (GI to GV). JEV has a well described enzootic cycle in endemic regions between swine and avian populations as amplification hosts and Culex species mosquitoes which act as the primary vector. Humans are incidental hosts with no known contributions to sustaining transmission cycles in nature. Vector-free routes of JEV transmission have been described through oronasal shedding of viruses among infected swine. The aim of this study was to characterize the fecal shedding of JEV from intradermally challenged swine. The objective of the study was to advance our understanding of how JEV transmission can be maintained in the absence of arthropod vectors. Our hypothesis is that JEV RNA will be detected in fecal swabs and resemble the shedding profile observed in swine oral fluids, peaking between days three and five. In this study fecal swabs were collected throughout a 28-day JEV challenge experiment in swine and samples were analyzed using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). Quantification of viral loads in fecal shedding will provide a more complete understanding of the potential host-host transmission in susceptible swine populations. Our results show that fecal shedding of JEV appears to mimic that of oral shedding, with peak viral loads detected around day five post-infection. The detection of JEV viral genomes in fecal specimens indicate a potential for fecal shedding to contribute to transmission of JEV in the absence of vectors. These findings are significant in developing control strategies to mitigate the agricultural and public health threats created by JEV in endemic regions.