From the field to the lab - An European view on the global spread of PEDV

Abstract

Porcine Epidemic Diarrhea Virus (PEDV) is a member of the genus Alphacoronavirus, in the family Coronaviridae, of the Nidovirales order and outbreaks of porcine epidemic diarrhoea (PED) were first recorded in England in the 1970s. Intriguingly the virus has since successfully made its way around the globe, while seemingly becoming extinct in parts of Europe before its recent return from Northern America. In this review we are re-evaluating the spread of PEDV, its biology and are looking at lessons learnt from both failure and success. While a new analysis of PEDV genomes demonstrates a wider heterogeneity of PEDV than previously anticipated with at least five rather than two genotypes, biological features of the virus and its replication also point towards credible control strategies to limit the impact of this re-emerging virus.

Keywords: Control; Diagnosis; Outbreak; PEDV; Sequence.

Fig. 1

Phylogenetic analysis of 40 representative PEDV full genome RNA sequences. The evolutionary history was inferred by using the Neighbor-Joining method, as described by Huang et al., 2013. Evolutionary analyses were conducted in MEGA6 (Tamura et al., 2013). Accession numbers, country and year of isolation are indicated, as provided by GenBank and the references therein. The resulting genotypes are numbered and colour-coded. A) Percentage identity/differences across the different genotypes. The genetic differences between genotypes are at least 2.5% as highlighted in the light blue box using the prototype PEDV strain CV777 as reference. This table also demonstrates that PEDV England-1-2000 (Genotype 5) is more diverse to any other genotype than these are to each other (>4.5%, pink box). B) The tree is drawn to scale, except for the out-groups bat coronavirus (BatCoV), porcine respiratory coronavirus (PRCV) and transmissible gastroenteritis virus (TGEV), which are shown for reference. Branch lengths other than the out-groups reflect the number of substitutions per site. The percentage of trees in which the associated taxa clustered together is shown next to the branches for values greater than 70%. Genotypes 1 and 2 are as inferred by Huang et al. (2013); Genotype 3 is represented by the recently sequenced Italian strain from 2009, while Genotype 4 is represented by two strains derived from recombination thus previously termed R (Huang et al., 2013). Genotype 5 is represented by the strain England-1-2000, the most distinct PEDV strain discovered so far.