North American domestic pigs are susceptible to experimental infection with Japanese encephalitis virus

So Lee Park,Kenneth R Burton,Stephen Higgs,D Scott Mcvey,Dana L Vanlandingham,Victoria B Ayers,Yan-Jang S Huang,Susan M Hettenbach,Amy C Lyons

doi:10.1038/s41598-018-26208-8

Abstract

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that is capable of causing encephalitic diseases in children. While humans can succumb to severe disease, the transmission cycle is maintained by viremic birds and pigs in endemic regions. Although JEV is regarded as a significant threat to the United States (U.S.), the susceptibility of domestic swine to JEV infection has not been evaluated. In this study, domestic pigs from North America were intravenously challenged with JEV to characterize the pathological outcomes. Systemic infection followed by the development of neutralizing antibodies were observed in all challenged animals. While most clinical signs were limited to nonspecific symptoms, virus dissemination and neuroinvasion was observed at the acute phase of infection. Detection of infectious viruses in nasal secretions suggest infected animals are likely to promote the vector-free transmission of JEV. Viral RNA present in tonsils at 28 days post infection demonstrates the likelihood of persistent infection. In summary, our findings indicate that domestic pigs can potentially become amplification hosts in the event of an introduction of JEV into the U.S. Vector-free transmission to immunologically naïve vertebrate hosts is also likely through nasal shedding of infectious viruses.

Highlights

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that has high human and veterinary public health significance
Our results demonstrate that North American domestic pigs, as used for commercial pork production, are susceptible to JEV infection
North American pigs infected with GI-b JEV JE-91 strain developed clinical signs including depression, fever, and minor weight loss followed by mild to moderate bilateral hind limb ataxia, which is a clinical finding often reported with other ambulatory abnormalities in horses infected with JEV6,21

Summary

Introduction

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that has high human and veterinary public health significance. The susceptibility of North American swine to JEV infection and its disease outcomes remains largely unknown despite the significant role that pigs play in JEV-endemic regions as efficient amplifying hosts[4,16]. The majority of published studies were performed with JEV strains belonging to genotype III (GIII), which was previously dominant in the endemic region but has been replaced by the rapidly emerging strains under the clade b of genotype I (GI-b)[10,17,18,19,20] Such a critical gap of knowledge precludes the comprehensive assessment needed to estimate the risk and develop effective countermeasures against the potential emergence of JEV in the United States (U.S.). Pathogenic outcomes and tissue tropism were characterized by detection of infectious viruses and viral genomes

Methods

Results

Conclusion