A descriptive survey of porcine epidemic diarrhea in pig populations in northern Vietnam.

Porcine epidemic diarrhea (PED) virus (PEDV) is a globally emerging and re-emerging epizootic swine virus that causes massive economic losses in the swine industry, with high mortality in piglets. In Vietnam, PED first emerged in 2009 and has now developed to an endemic stage. This is the first cross-sectional survey performed to evaluate the proportion of PEDV-positive swine farms in Vietnam from January 2018 to February 2019. Fecal samples from 327 pig farms in northern Vietnam were collected and tested for PEDV infection by reverse transcription-loop-mediated isothermal amplification (RT-LAMP) method. The proportion of PEDV-positive farms was 30.9% and PEDV-positive farms were distributed throughout the study area. The highest proportion of PEDV-positive farms was 70% (7/10) among nucleus production type farms (P < 0.05). Higher proportions of PEDV-positive farms were found in the Northeast and Red River Delta areas, which are the major areas of pig production (P < 0.05). The proportion of PEDV-positive farms was higher among larger farms (P < 0.05). Our findings illustrate the high proportion of PEDV-positive farms in the Vietnamese pig population and will help to better understand the epidemiological dynamics of PED infection, to estimate impact, and establish and improve prevention and control measures.

Molecular characterization of a Korean porcine epidemic diarrhea virus strain NB1.

In Korea, for the past 30 years (1987-present), porcine epidemic diarrhea (PED) has been established as an endemic situation in which multiple genogroups of classical G1 and G2b, and the recently introduced pandemic G2a, coexisted. Because of the dynamic nature of the virus, continuous field monitoring for PEDV strains is required. This study is the first to reveal prevalence of PEDV in 9 sampling provinces, with an overall detection rate of 6.70%. Porcine endemic diarrhea virus (PEDV) was present in pigs of all ages, especially in the non-PED vaccinated groups. The highest detection rate was in the finisher group (2.34%), followed by that in the newborn group (1.56%). Secondly, using Sanger sequencing, this study recovered a complete genome (28 005 nucleotides long) of NB1 strain from a farm severely affected by PED. Analyses of nucleotide and deduced amino acid sequences showed that NB1 differed from 18 other Korean PEDV mostly in 4 protein coding genes: ORF1a, ORF1b, S, and N. Two amino acid substitutions (V635E and Y681Q) in the COE and S1D neutralizing epitopes of NB1 resulted in antigenic index alteration of the adjacent sites, one of which contributed to a mutation that escaped neutralizing antibodies.

En Corée, pour les 30 dernières années (1987 à ce jour), la diarrhée épidémique porcine (DEP) s'est établie comme une situation endémique dans laquelle de multiples génogroupes des classiques G1 et G2b, ainsi que le G2a pandémique récemment introduit, ont coexisté. Étant donné la nature dynamique du virus, un suivi continu sur le terrain des souches de DEP est requis. La présente étude est la première à révéler la prévalence de DEP dans neuf provinces échantillonnées, avec un taux de détection global de 6,70 %. Le virus de la DEP (VDEP) était présent chez les porcs de tout âge, spécialement dans les groupes d'animaux non-vaccinés contre la DEP. Les animaux dans le groupe en finition avaient taux de détection le plus élevé (2,34 %), suivi par ceux du groupe des nouveau-nés (1,56 %). Deuxièmement, en utilisant le séquençage de Sanger, nous avons récupéré un génome complet (28 005 nucléotides de long) de la souche NB1 sur une ferme sévèrement affectée par la DEP. L'analyse des nucléotides et des séquences d'acides aminés déduites a montré que NB1 différaient de 18 autres VDEP coréens principalement dans quatre gènes codant pour protéines: ORF1a, ORF1b, S, et N. Deux substitutions d'acides aminés (V635E et Y681Q) dans les épitopes neutralisants COE et S1D de NB1 ont résulté en une altération de l'index antigénique des sites adjacents, dont l'un contribuait à une mutation qui échappait aux anticorps neutralisants.(Traduit par Docteur Serge Messier).