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Emergence of porcine epidemic diarrhea virus in southern Germany.

Stadler J, Zoels S, Fux R, Hanke D, Pohlmann A, Blome S, Weissenböck H, Weissenbacher-Lang C, Ritzmann M, Ladinig A - BMC Vet. Res. (2015)

Bottom Line: In the fattening farm yellowish, watery diarrhea without evidence of mucus or blood was associated with a massive reduction of feed consumption.Slightly lower identities were found with other strains from the US and Asia.Current strains were clearly different from isolates found in the 1980s and were closely related to a PEDV variant found in the US in 2014.

View Article: PubMed Central - PubMed

Affiliation: Clinic for Swine at the Centre for Clinical Veterinary Medicine, Ludwig-Maximilians University, Oberschleissheim, Germany. j.stadler@med.vetmed.uni-muenchen.de.

ABSTRACT

Background: Over the last years, porcine epidemic diarrhea virus (PEDV) has caused devastating enteric diseases in the US and several countries in Asia, while outbreaks in Europe have only been reported sporadically since the 1980s. At present, only insufficient information is available on currently circulating PEDV strains in Europe and their impact on the European swine industry. In this case report, we present epidemic outbreaks of porcine epidemic diarrhea in three farms in South-Western Germany.

Case presentation: Epidemic outbreaks of diarrhea affecting pigs of all age groups were reported in three farms, one fattening farm and two piglet producing farms, in South-Western Germany between May and November 2014. In the fattening farm yellowish, watery diarrhea without evidence of mucus or blood was associated with a massive reduction of feed consumption. Severity of clinical signs and mortality in young suckling pigs varied significantly between the two affected sow farms. While mortality in suckling piglets reached almost 70 % in one sow herd, no increase in suckling piglet mortality was observed in the second sow farm. In all three cases, PEDV was confirmed in feces and small intestines by RT-qPCR. Phylogenetic analyses based on full-length PEDV genomes revealed high identity among strains from all three herds. Moreover, the German strains showed very high nucleotide identity (99.4 %) with a variant of PEDV (OH851) that was isolated in the United States in January 2014. This strain with insertions and deletions in the S-gene (so called INDEL strains) was reported to show lower virulence. Slightly lower identities were found with other strains from the US and Asia.

Conclusion: Phylogenetic information on the distribution of PEDV strains in Europe is severely lacking. In this case report we demonstrate that acute outbreaks of PEDV occurred in southern Germany in 2014. Current strains were clearly different from isolates found in the 1980s and were closely related to a PEDV variant found in the US in 2014. Moreover, the present case report indicates that variant strains of PEDV, containing insertions and deletions in the S gene, which were reported to be of lower virulence, might be able to cause high mortality in suckling piglets.

No MeSH data available.


Related in: MedlinePlus

Localization of viral nucleic acid in enterocytes by in situ hybridization. a The cytoplasm of the majority of villous enterocytes is positively labelled in a case with +++ score. b Only few, scattered enterocytes are positive in a case with + score. Bar = 80 μm
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Fig4: Localization of viral nucleic acid in enterocytes by in situ hybridization. a The cytoplasm of the majority of villous enterocytes is positively labelled in a case with +++ score. b Only few, scattered enterocytes are positive in a case with + score. Bar = 80 μm

Mentions: Severely affected animals from all three farms (Farm A: 3 feeder pigs, Farm B: 4 suckling piglets, Farm C: 25 suckling piglets) were submitted for pathological investigations. Gross lesions were limited to the intestines and characterized by distended, thin and transparent intestinal walls, mainly observed in the small intestines but partially also in the colon region (Fig. 2). The intestinal lumen contained yellow, watery and frothy fluid. In individual pigs intestinal contents were completely absent. Tissue samples from small intestines were fixed in 10 % neutral buffered formalin and embedded in paraffin wax. Tissue sections were stained with hematoxylin and eosin (H&E) for microscopic examination by standard methods. Histology was characterized by atrophic enteritis, which included shortening, blunting and fusion of the villi, occasionally with vacuolation and exfoliation of enterocytes (Fig. 3). There were individually differing grades of the lesions. In farm C a more detailed evaluation of histological lesions and an additional localization of viral nucleic acid within lesions was performed due to the availability of higher numbers of severely affected piglets. In four of the 25 investigated piglets lesions were categorized as severe, in nine piglets as moderate and in 12 piglets as mild (Table 1). A chromogenic in situ hybridization (ISH) procedure was developed for semi-quantitative analysis of viral nucleic acid present within enterocytes. An oligonucleotide probe with the potential to hybridize with all representatives of PEDV was designed. Probe design was based on extensive homology studies on available nucleocapsid gene sequences from GenBank using the software Sci Ed Central for Windows 95 (Scientific & Educational Software, Cary, NC, USA). The resulting probe sequence was: 5’-GCATCCTTGACAGCAGCCACCAGATCATCGCGTGAT-3’. The probe sequence was submitted to Basic Local Alignment Search Tool (BLAST) [12] to search against GenBank sequences and to exclude unintentional cross-reactivity with other organisms. The ISH procedure followed a previously published protocol [13]. The probe concentration was 35 ng/μl. As negative controls paraffin wax-embedded small intestinal tissue samples of a healthy piglet and of a piglet experimentally infected with transmissible gastroenteritis virus (TGEV), an unrelated alphacoronavirus, were used. The proportion of positive enterocytes was assessed semiquantitatively using the score +++ for abundant (between 75 % and 100 % of enterocytes positive), ++ for moderate (between 25 % to 75 % of enterocytes positive) and + for few (less than 25 % of enterocytes positive) signals. By ISH, viral signals were found exclusively in the cytoplasm of enterocytes (Fig. 4). The vast majority of infected cells was present in the villi but occasionally there were positive crypt epithelia too. In 9 piglets necropsied from farm C there were abundant ISH signals (+++) and in 8 cases each, moderate (++) or few (+) signals were detected. The amount of positive cells did not exactly correspond with the histological scores (Table 1).Fig. 2


Emergence of porcine epidemic diarrhea virus in southern Germany.

Stadler J, Zoels S, Fux R, Hanke D, Pohlmann A, Blome S, Weissenböck H, Weissenbacher-Lang C, Ritzmann M, Ladinig A - BMC Vet. Res. (2015)

Localization of viral nucleic acid in enterocytes by in situ hybridization. a The cytoplasm of the majority of villous enterocytes is positively labelled in a case with +++ score. b Only few, scattered enterocytes are positive in a case with + score. Bar = 80 μm
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4487554&req=5

Fig4: Localization of viral nucleic acid in enterocytes by in situ hybridization. a The cytoplasm of the majority of villous enterocytes is positively labelled in a case with +++ score. b Only few, scattered enterocytes are positive in a case with + score. Bar = 80 μm
Mentions: Severely affected animals from all three farms (Farm A: 3 feeder pigs, Farm B: 4 suckling piglets, Farm C: 25 suckling piglets) were submitted for pathological investigations. Gross lesions were limited to the intestines and characterized by distended, thin and transparent intestinal walls, mainly observed in the small intestines but partially also in the colon region (Fig. 2). The intestinal lumen contained yellow, watery and frothy fluid. In individual pigs intestinal contents were completely absent. Tissue samples from small intestines were fixed in 10 % neutral buffered formalin and embedded in paraffin wax. Tissue sections were stained with hematoxylin and eosin (H&E) for microscopic examination by standard methods. Histology was characterized by atrophic enteritis, which included shortening, blunting and fusion of the villi, occasionally with vacuolation and exfoliation of enterocytes (Fig. 3). There were individually differing grades of the lesions. In farm C a more detailed evaluation of histological lesions and an additional localization of viral nucleic acid within lesions was performed due to the availability of higher numbers of severely affected piglets. In four of the 25 investigated piglets lesions were categorized as severe, in nine piglets as moderate and in 12 piglets as mild (Table 1). A chromogenic in situ hybridization (ISH) procedure was developed for semi-quantitative analysis of viral nucleic acid present within enterocytes. An oligonucleotide probe with the potential to hybridize with all representatives of PEDV was designed. Probe design was based on extensive homology studies on available nucleocapsid gene sequences from GenBank using the software Sci Ed Central for Windows 95 (Scientific & Educational Software, Cary, NC, USA). The resulting probe sequence was: 5’-GCATCCTTGACAGCAGCCACCAGATCATCGCGTGAT-3’. The probe sequence was submitted to Basic Local Alignment Search Tool (BLAST) [12] to search against GenBank sequences and to exclude unintentional cross-reactivity with other organisms. The ISH procedure followed a previously published protocol [13]. The probe concentration was 35 ng/μl. As negative controls paraffin wax-embedded small intestinal tissue samples of a healthy piglet and of a piglet experimentally infected with transmissible gastroenteritis virus (TGEV), an unrelated alphacoronavirus, were used. The proportion of positive enterocytes was assessed semiquantitatively using the score +++ for abundant (between 75 % and 100 % of enterocytes positive), ++ for moderate (between 25 % to 75 % of enterocytes positive) and + for few (less than 25 % of enterocytes positive) signals. By ISH, viral signals were found exclusively in the cytoplasm of enterocytes (Fig. 4). The vast majority of infected cells was present in the villi but occasionally there were positive crypt epithelia too. In 9 piglets necropsied from farm C there were abundant ISH signals (+++) and in 8 cases each, moderate (++) or few (+) signals were detected. The amount of positive cells did not exactly correspond with the histological scores (Table 1).Fig. 2

Bottom Line: In the fattening farm yellowish, watery diarrhea without evidence of mucus or blood was associated with a massive reduction of feed consumption.Slightly lower identities were found with other strains from the US and Asia.Current strains were clearly different from isolates found in the 1980s and were closely related to a PEDV variant found in the US in 2014.

View Article: PubMed Central - PubMed

Affiliation: Clinic for Swine at the Centre for Clinical Veterinary Medicine, Ludwig-Maximilians University, Oberschleissheim, Germany. j.stadler@med.vetmed.uni-muenchen.de.

ABSTRACT

Background: Over the last years, porcine epidemic diarrhea virus (PEDV) has caused devastating enteric diseases in the US and several countries in Asia, while outbreaks in Europe have only been reported sporadically since the 1980s. At present, only insufficient information is available on currently circulating PEDV strains in Europe and their impact on the European swine industry. In this case report, we present epidemic outbreaks of porcine epidemic diarrhea in three farms in South-Western Germany.

Case presentation: Epidemic outbreaks of diarrhea affecting pigs of all age groups were reported in three farms, one fattening farm and two piglet producing farms, in South-Western Germany between May and November 2014. In the fattening farm yellowish, watery diarrhea without evidence of mucus or blood was associated with a massive reduction of feed consumption. Severity of clinical signs and mortality in young suckling pigs varied significantly between the two affected sow farms. While mortality in suckling piglets reached almost 70 % in one sow herd, no increase in suckling piglet mortality was observed in the second sow farm. In all three cases, PEDV was confirmed in feces and small intestines by RT-qPCR. Phylogenetic analyses based on full-length PEDV genomes revealed high identity among strains from all three herds. Moreover, the German strains showed very high nucleotide identity (99.4 %) with a variant of PEDV (OH851) that was isolated in the United States in January 2014. This strain with insertions and deletions in the S-gene (so called INDEL strains) was reported to show lower virulence. Slightly lower identities were found with other strains from the US and Asia.

Conclusion: Phylogenetic information on the distribution of PEDV strains in Europe is severely lacking. In this case report we demonstrate that acute outbreaks of PEDV occurred in southern Germany in 2014. Current strains were clearly different from isolates found in the 1980s and were closely related to a PEDV variant found in the US in 2014. Moreover, the present case report indicates that variant strains of PEDV, containing insertions and deletions in the S gene, which were reported to be of lower virulence, might be able to cause high mortality in suckling piglets.

No MeSH data available.


Related in: MedlinePlus