key: cord-0008256-lw0r3prt
authors: Opriessnig, Tanja
title: Re-emergence of porcine epidemic diarrhea virus in the global pig population
date: 2015-03-25
journal: Vet J
DOI: 10.1016/j.tvjl.2015.03.019
sha: a71c66cae802debdc8d1ecd5e32b1c4c94e1ed3b
doc_id: 8256
cord_uid: lw0r3prt

nan

The review on the etiology, epidemiology, pathogenesis and immunoprophylaxis of porcine epidemic diarrhea virus (PEDV) infection by Dr Kwonil Jung and Dr Linda Saif from the Ohio State University, USA, published in this issue of The Veterinary Journal (Jung and Saif, 2015) is very timely considering the recent introduction and emergence of PEDV in North America in 2013 and the ongoing outbreaks attributed to novel strains of PEDV in Asia and now also in Europe.

Coronaviruses such as PEDV continue to remain on the radar of global health professionals mainly due to their ability to adapt rapidly to changing conditions. Certainly the outbreaks of severe acute respiratory syndrome coronavirus at the beginning of the 21st century, or more recently the emergence of the Middle East respiratory syndrome coronavirus in 2012 in Saudi Arabia, give reason to fear new epidemics in humans (Plowright et al., 2015) . Like other coronaviruses, PEDV has been found to mutate quickly and today it is well recognized that several distinct PEDV variants are circulating in the global pig population (Jung and Saif, 2015) . Furthermore, another coronavirus associated with enteric disease, porcine deltacoronavirus (PDCoV), recently emerged in US pigs causing clinical signs similar to PEDV as confirmed by experimental inoculation of gnotobiotic piglets (Jung and Saif, 2015) .

In their review, Jung and Saif (2015) describe that the disease associated with PEDV is characterized by acute onset of profuse liquid diarrhea, inappetence, vomiting and lethargy commonly connected with high morbidity and mortality rates, especially when young suckling pigs in naïve pig populations become infected. Clinically in pigs, PEDV associated diarrhea is indistinguishable from diarrhea caused by other viral pathogens including other coronaviruses, transmissible gastroenteritis virus and PDCoV, or rotavirus. Molecular investigations have highlighted the potential diversity of PEDV strains and the need to constantly re-evaluate the most prevalent PEDV strain to keep diagnostic tools up date (Jung and Saif, 2015) . PEDV mainly targets small intestinal villus enterocytes in the jejunum and ileum which express large amounts of the cellular receptor of PEDV, aminopeptidase N, although PEDV is capable of infecting villous epithelial cells of the entire small and large intestines. Once in the cell, PEDV causes acute necrosis of the cell resulting in marked villous atrophy (Jung and Saif, 2015) .

The PEDV was recognized more than three decades ago in the UK (Wood, 1977) and later spread through Europe and reached Asia in the 1980s. In times with large scale pig movements within and across farms, states and continents, it is somewhat expected that viruses previously confined to certain geographic areas will increasingly spread and emerge in distant locations. In April 2013, PEDV was reported for the first time in the Midwestern United States (Stevenson et al., 2013) and it has since been confirmed in Canada, Mexico, Columbia, the Caribbean and Hawaii. In the US alone, PEDV has caused losses of over seven million pigs causing high economic losses to the pork industry (Jung and Saif, 2015) . The PEDV strains identified in US pigs in 2013 were closely related to strains reported in China during 2011 and 2012 indicating a relationship, although the precise transmission route responsible for the introduction of PEDV into North America remains undetermined (Jung and Saif, 2015) . Jung and Saif (2015) indicate that preventive strategies to reduce the impact of PEDV need to focus on pregnant sows during epidemics mainly to reduce mortality in suckling pigs whereas active immunization of growing pigs is important for the control of endemic PEDV infection. Current vaccination protocols that have been implemented in North America during 2013 and 2014 target sows and have been effective in reducing mortality associated with PEDV. However, much more needs to be learned on antigen preparations, vaccine strains and vaccination routes in future.

The review by Jung and Saif (2015) provides an excellent summary of the current knowledge of PEDV infection and will be of use for the academic community as well as swine veterinarians. PEDV appears to be circumventing biosecurity and vaccination protocols highlighting the need for ongoing detailed molecular analyses to recognize emerging strains with a higher pathogenic potential for targeted vaccine design.

Tanja Opriessnig

Porcine epidemic diarrhea virus infection: Etiology, epidemiology, pathogenesis and immunoprophylaxis

Ecological dynamics of emerging bat virus spillover

Emergence of porcine epidemic diarrhea virus in the United States: Clinical signs, lesions, and viral genomic sequences

An apparently new syndrome of porcine epidemic diarrhoea

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