Porcine Hemagglutinating Encephalomyelitis Virus: A Review
- 1Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, United States
- 2Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, United States
The porcine hemagglutinating encephalomyelitis virus (PHEV) is classify as a member of genus Betacoronavirus, family Coronaviridae, sub-family Cornavirinae, and order Nidovirales. PHEV share the same genomic organization, replication strategy, and expression of viral proteins as other nidoviruses. PHEV produces vomiting and wasting disease and/or encephalomyelitis, being the only known neurotropic coronavirus affecting pigs. First clinical outbreak was reported in 1957 in Ontario, Canada. Although, pigs are the only species known to be susceptible to natural PHEV infections, the virus displays neurotropism in mice and Wistar rats. Clinical disease, morbidity and mortality are age-dependent and generally reported only in piglets under four weeks old. The primary site of replication of PHEV in pigs is the respiratory tract, and it can be further spread to the central nervous system through the peripheral nervous system via different pathways. PHEV diagnosis can be achieved by a combination of direct and indirect detection methods. The virus can be isolated from different tissues within the first few days after the onset of clinical signs using primary and secondary pig cell lines. PHEV agglutinates the erythrocytes of mice, rats, chickens, and several other animals. PCR-based methods are useful to identify and subsequently isolate animals that are actively shedding the virus. The ability to detect antibodies allows producers to know the status of first-litter gilts and evaluate their risk of tier offspring to infection. PHEV is highly prevalent and circulates subclinically in most swine herds worldwide. PHEV-related disease is not clinically relevant in most of the swine-producing countries, most likely because of dams are immune to PHEV and may confer passive immunity to their offspring. However, PHEV should be considered a major source of economic loss because of the high mortality on farms with high gilt replacement rates, specific pathogen-free animals, and gnotobiotic swine herds. Thus, in the absence of current PHEV vaccines, promoting virus circulation on farms with early exposure to gilts and young sows could induce maternal immunity and prevent disease in piglets.
Keywords: Porcine hemagglutinating encephalomyelitis virus, Coronavirus, Vomiting and wasting disease, Encephalomyelitis, Nidovirus
Received: 08 Nov 2018;
Accepted: 07 Feb 2019.
Edited by:Anan Jongkaewwattana, National Center for Genetic Engineering and Biotechnology (BIOTEC), Thailand
Reviewed by:Faten A. Okda, St. Jude Children's Research Hospital, United States
Wenqi He, Jilin University, China
Copyright: © 2019 Mora-Díaz, Pineyro, Houston, Zimmerman and Gimenez-Lirola. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Dr. Pablo Pineyro, Iowa State University, Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Ames, United States, firstname.lastname@example.org
Dr. Luis G. Gimenez-Lirola, Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, 50011-1134, Iowa, United States, email@example.com