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Porcine epidemic diarrhoea: new insights into an old disease

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ABSTRACT

Porcine epidemic diarrhea (PED) is an enteric disease in swine caused by an alphacoronavirus. It affects swine of all ages causing acute diarrhoea and can lead to severe dehydration and death in suckling piglets. Being recognized for the first time in Europe and Asia during the seventies and the eighties, respectively, it has remained a relevant cause of diarrhea outbreaks in Asia for years and to the present. It has become a major concern in swine production since 2013 when the virus was detected for first time in the USA and in other American countries causing a high number of pig deaths and significant economic losses. The present review aims at approaching the reader to the state of the art of PED giving answer to some of the most recent questions which have arisen related to this disease.

No MeSH data available.


Phylogenetic analysis using the neighbor-joining method based on the nucleotide sequences corresponding to the whole genome (a) and full-length S gene (b) of a selection of PEDV isolates based on geographical and time criteria. Bootstrap values calculated from 1000 replicate analyses are shown in the nodes
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Fig1: Phylogenetic analysis using the neighbor-joining method based on the nucleotide sequences corresponding to the whole genome (a) and full-length S gene (b) of a selection of PEDV isolates based on geographical and time criteria. Bootstrap values calculated from 1000 replicate analyses are shown in the nodes

Mentions: Some insights have been obtained related to the virulence of different strains. In the USA, at least two main variants of PEDV have been recently identified using molecular methods. The first one seems to be a highly virulent virus and similar to viruses described in several Asian countries after 2010 while the second, the S INDEL variant, has been associated to mild clinical outbreaks [59]. This S INDEL variant includes some particular insertions and deletions in the S gene and is also similar to some Asian isolates, part of which were recovered before 2010. The classical European reference strain of PEDV CV777 is also an S INDEL isolate although it is located in a different cluster and well differentiated from American INDEL isolates (Fig. 1a and b). PEDV isolates recovered in European countries (Germany, Italy, Belgium, the Netherlands and France) in 2014 and 2015 have been characterized and all of them were found to be INDEL isolates similar to the variant described in the USA [13–19]. Most of these recent PED outbreaks in Europe occurred in fattening farms and, as expected, no mortality was observed. However, PEDV isolates recently recovered in severe outbreaks of PEDV in Ukraine have shown a genome nucleotide similarity reaching 99.8 % with non-INDEL isolates from the United States and Mexico [20]. So far, this has been the only report of PEDV non-INDEL isolates in Europe. Apart from differences in the virulence of the PEDV strains, many other parameters including management, immune status of the population and herd sanitary status could also explain variations in the clinical outcome of PED outbreaks [31]. Thus, the contribution of co-infections with other viruses, particularly with other enteric viruses such as porcine delta coronavirus (PDCoV) or the recently described mammalian orthoreovirus 3 (MRV3) has also been pointed out. Both viruses have been detected in faecal samples collected from PEDV positive farms in the USA. PDCoV has been associated with mild to moderate diarrhoea in experimentally inoculated naïve suckling piglets [33] while MRV3 caused severe diarrhoea with 100 % mortality in 3-day-old piglets [60].Fig. 1


Porcine epidemic diarrhoea: new insights into an old disease
Phylogenetic analysis using the neighbor-joining method based on the nucleotide sequences corresponding to the whole genome (a) and full-length S gene (b) of a selection of PEDV isolates based on geographical and time criteria. Bootstrap values calculated from 1000 replicate analyses are shown in the nodes
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5382377&req=5

Fig1: Phylogenetic analysis using the neighbor-joining method based on the nucleotide sequences corresponding to the whole genome (a) and full-length S gene (b) of a selection of PEDV isolates based on geographical and time criteria. Bootstrap values calculated from 1000 replicate analyses are shown in the nodes
Mentions: Some insights have been obtained related to the virulence of different strains. In the USA, at least two main variants of PEDV have been recently identified using molecular methods. The first one seems to be a highly virulent virus and similar to viruses described in several Asian countries after 2010 while the second, the S INDEL variant, has been associated to mild clinical outbreaks [59]. This S INDEL variant includes some particular insertions and deletions in the S gene and is also similar to some Asian isolates, part of which were recovered before 2010. The classical European reference strain of PEDV CV777 is also an S INDEL isolate although it is located in a different cluster and well differentiated from American INDEL isolates (Fig. 1a and b). PEDV isolates recovered in European countries (Germany, Italy, Belgium, the Netherlands and France) in 2014 and 2015 have been characterized and all of them were found to be INDEL isolates similar to the variant described in the USA [13–19]. Most of these recent PED outbreaks in Europe occurred in fattening farms and, as expected, no mortality was observed. However, PEDV isolates recently recovered in severe outbreaks of PEDV in Ukraine have shown a genome nucleotide similarity reaching 99.8 % with non-INDEL isolates from the United States and Mexico [20]. So far, this has been the only report of PEDV non-INDEL isolates in Europe. Apart from differences in the virulence of the PEDV strains, many other parameters including management, immune status of the population and herd sanitary status could also explain variations in the clinical outcome of PED outbreaks [31]. Thus, the contribution of co-infections with other viruses, particularly with other enteric viruses such as porcine delta coronavirus (PDCoV) or the recently described mammalian orthoreovirus 3 (MRV3) has also been pointed out. Both viruses have been detected in faecal samples collected from PEDV positive farms in the USA. PDCoV has been associated with mild to moderate diarrhoea in experimentally inoculated naïve suckling piglets [33] while MRV3 caused severe diarrhoea with 100 % mortality in 3-day-old piglets [60].Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Porcine epidemic diarrhea (PED) is an enteric disease in swine caused by an alphacoronavirus. It affects swine of all ages causing acute diarrhoea and can lead to severe dehydration and death in suckling piglets. Being recognized for the first time in Europe and Asia during the seventies and the eighties, respectively, it has remained a relevant cause of diarrhea outbreaks in Asia for years and to the present. It has become a major concern in swine production since 2013 when the virus was detected for first time in the USA and in other American countries causing a high number of pig deaths and significant economic losses. The present review aims at approaching the reader to the state of the art of PED giving answer to some of the most recent questions which have arisen related to this disease.

No MeSH data available.