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Emergence of a virulent porcine reproductive and respiratory syndrome virus (PRRSV) 1 strain in Lower Austria

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ABSTRACT

Background: In spring 2015, an outbreak of porcine reproductive and respiratory syndrome (PRRS) struck Lower Austria caused by a PRRS virus (PRRSV) strain spreading rapidly among both previously PRRSV negative and vaccinated pig herds. This case report describes the first well-documented emergence of the PRRSV strain responsible for this outbreak.

Case presentation: A PRRSV seronegative piglet-producing farm in Lower Austria encountered losses in foetuses and suckling piglets of up to 90 %; clinical signs in sows and nursery piglets included fever and reduced feed intake. Additionally, high percentages of repeat breeders and losses of up to 40 % in nursery piglets occurred. An infection with PRRSV was suggested by the detection of antibodies by enzyme linked immunosorbent assay and confirmed by quantitative real time PCR. The underlying PRRSV strain, termed AUT15-33, was isolated by passage on porcine alveolar macrophages, partially sequenced (ORF2-7) and grouped as PRRSV-1, subtype 1. In phylogenetic analysis of the genome region coding for the structural proteins, ORF2-7, AUT15-33 clustered with Belgian strains but identities were as low as 88 %. In contrast, analysis of ORF7 sequences revealed a close relationship to Croatian strains from 2012 with an identity of 94 – 95 %.

Conclusions: In the year following the outbreak, the same PRRSV strain was identified repeatedly in different regions of Austria. It can be speculated that the new strain has novel advantageous properties.

No MeSH data available.


Related in: MedlinePlus

Virus isolation of field strain AUT15-33. Serum of nine acutely affected nursery piglets was inoculated on porcine alveolar macrophages (PAM). After two days cells were fixed with methanol-acetone and immunofluorescence stained with an anti-PRRSV-N-protein monoclonal antibody (kindly provided by A. Saalmüller, Vienna) [39] and goat-anti-mouse conjugated with Cy3 as a secondary antibody. Varying cytopathic effects were seen and a PRRSV-specific immunofluorescence staining was detected (serum samples #33 and 38 are shown exemplarily)
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Fig4: Virus isolation of field strain AUT15-33. Serum of nine acutely affected nursery piglets was inoculated on porcine alveolar macrophages (PAM). After two days cells were fixed with methanol-acetone and immunofluorescence stained with an anti-PRRSV-N-protein monoclonal antibody (kindly provided by A. Saalmüller, Vienna) [39] and goat-anti-mouse conjugated with Cy3 as a secondary antibody. Varying cytopathic effects were seen and a PRRSV-specific immunofluorescence staining was detected (serum samples #33 and 38 are shown exemplarily)

Mentions: Since the clinical course of infection was unusually severe for Austrian conditions and reports about PRRS outbreaks in the same region accumulated, the PRRSV strain was further characterized. Blood samples were collected from nine nursery piglets showing acute clinical signs like fever and reduced alertness in order to isolate the virus and perform RT-PCR and sequencing. To this end naïve primary cells (PAM) and the cell line MARC-145 were inoculated with serum from each piglet. A PRRSV-specific immunofluorescence staining of PAM (Fig. 4) but not of MARC-145 cells could be detected after two days. This finding was confirmed after passaging the supernatant on new PAM and MARC-145 cells (data not shown). In accordance, all nine serum samples were tested highly positive when using a commercial PRRSV quantitative RT-PCR (qRT-PCR) Kit with genome copy numbers between 1.4 x 108 and 4.3 x 109 (Table 1). In conclusion, a new PRRSV strain, named AUT15-33, could be isolated from serum of piglets showing acute illness on primary PAM.Fig. 4


Emergence of a virulent porcine reproductive and respiratory syndrome virus (PRRSV) 1 strain in Lower Austria
Virus isolation of field strain AUT15-33. Serum of nine acutely affected nursery piglets was inoculated on porcine alveolar macrophages (PAM). After two days cells were fixed with methanol-acetone and immunofluorescence stained with an anti-PRRSV-N-protein monoclonal antibody (kindly provided by A. Saalmüller, Vienna) [39] and goat-anti-mouse conjugated with Cy3 as a secondary antibody. Varying cytopathic effects were seen and a PRRSV-specific immunofluorescence staining was detected (serum samples #33 and 38 are shown exemplarily)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
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getmorefigures.php?uid=PMC5382404&req=5

Fig4: Virus isolation of field strain AUT15-33. Serum of nine acutely affected nursery piglets was inoculated on porcine alveolar macrophages (PAM). After two days cells were fixed with methanol-acetone and immunofluorescence stained with an anti-PRRSV-N-protein monoclonal antibody (kindly provided by A. Saalmüller, Vienna) [39] and goat-anti-mouse conjugated with Cy3 as a secondary antibody. Varying cytopathic effects were seen and a PRRSV-specific immunofluorescence staining was detected (serum samples #33 and 38 are shown exemplarily)
Mentions: Since the clinical course of infection was unusually severe for Austrian conditions and reports about PRRS outbreaks in the same region accumulated, the PRRSV strain was further characterized. Blood samples were collected from nine nursery piglets showing acute clinical signs like fever and reduced alertness in order to isolate the virus and perform RT-PCR and sequencing. To this end naïve primary cells (PAM) and the cell line MARC-145 were inoculated with serum from each piglet. A PRRSV-specific immunofluorescence staining of PAM (Fig. 4) but not of MARC-145 cells could be detected after two days. This finding was confirmed after passaging the supernatant on new PAM and MARC-145 cells (data not shown). In accordance, all nine serum samples were tested highly positive when using a commercial PRRSV quantitative RT-PCR (qRT-PCR) Kit with genome copy numbers between 1.4 x 108 and 4.3 x 109 (Table 1). In conclusion, a new PRRSV strain, named AUT15-33, could be isolated from serum of piglets showing acute illness on primary PAM.Fig. 4

View Article: PubMed Central - PubMed

ABSTRACT

Background: In spring 2015, an outbreak of porcine reproductive and respiratory syndrome (PRRS) struck Lower Austria caused by a PRRS virus (PRRSV) strain spreading rapidly among both previously PRRSV negative and vaccinated pig herds. This case report describes the first well-documented emergence of the PRRSV strain responsible for this outbreak.

Case presentation: A PRRSV seronegative piglet-producing farm in Lower Austria encountered losses in foetuses and suckling piglets of up to 90 %; clinical signs in sows and nursery piglets included fever and reduced feed intake. Additionally, high percentages of repeat breeders and losses of up to 40 % in nursery piglets occurred. An infection with PRRSV was suggested by the detection of antibodies by enzyme linked immunosorbent assay and confirmed by quantitative real time PCR. The underlying PRRSV strain, termed AUT15-33, was isolated by passage on porcine alveolar macrophages, partially sequenced (ORF2-7) and grouped as PRRSV-1, subtype 1. In phylogenetic analysis of the genome region coding for the structural proteins, ORF2-7, AUT15-33 clustered with Belgian strains but identities were as low as 88 %. In contrast, analysis of ORF7 sequences revealed a close relationship to Croatian strains from 2012 with an identity of 94 – 95 %.

Conclusions: In the year following the outbreak, the same PRRSV strain was identified repeatedly in different regions of Austria. It can be speculated that the new strain has novel advantageous properties.

No MeSH data available.


Related in: MedlinePlus