Porcine epidemic diarrhoea virus: a comprehensive review of molecular epidemiology, diagnosis, and vaccines

Abstract

The porcine epidemic diarrhoea virus (PEDV), a member of the Coronaviridae family, causes acute diarrhoea and dehydration in pigs. Although it was first identified in Europe, it has become increasingly problematic in many Asian countries, including Korea, China, Japan, the Philippines, and Thailand. The economic impacts of the PEDV are substantial, given that it results in significant morbidity and mortality in neonatal piglets and is associated with increased costs related to vaccination and disinfection. Recently, progress has been made in understanding the molecular epidemiology of PEDV, thereby leading to the development of new vaccines. In the current review, we first describe the molecular and genetic characteristics of the PEDV. Then we discuss its molecular epidemiology and diagnosis, what vaccines are available, and how PEDV can be treated.

Fig. 1

Photographic records of PEDV outbreaks. During a 2006 outbreak on a commercial farm in Kimpo. South Korean, piglets <1 week of age died from severe watery diarrhoea after showing signs of dehydration. After the acute outbreak, piglets were anorectic, depressed, vomiting, and producing water faeces that did not contain any signs of blood. Necropsies of deceased piglets from the Kimpo outbreak uncovered gross lesions in the small intestines, which were typically fluidic, distended, and yellow, containing a mass of curdled, undigested milk. Atrophy of the villi caused the walls of the small intestines to become thin and almost transparent

Fig. 2

Schematic representation of the PEDV genome based on the CV777 (GenBank accession No. AF353511) strain

Fig. 3

Relationships among PEDVs isolated from various countries based on the partial S gene including epitope region. The phylogenetic tree was constructed using the neighbor-joining method in MEGA version 5.05 with pairwise distances [99]. Bootstrap values (based on 1,000 replicates) for each node are given if >60%. The scale bar indicates nucleotide substitutions per site. Asterisk represents PEDV isolate whose sequence available in GenBank database was shorter as compared to that of other reference strains. PEDVs isolated from various countries were marked with various colors: Europe (black), Korea (blue), China (red), Japan (olive green), Thailand (green) and Viet Nam (purple) (Color figure online)