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

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

Phylogenetic analysis based on ORF2-7 nucleotide sequences of 52 PRRSV-1 strains and PRRSV-2 prototype VR2332 as an out-group. The PRRSV strain presented in this study is marked with a solid box and the associated sub-tree is highlighted with a dotted box. The tree was constructed with the software CLC Sequence Viewer 7.6 (CLCBIO, Aarhus, Denmark) using the neighbour joining method with the numbers at the nodes representing bootstrap values in % of 1000 replicates. The ORF2-7 sequence of AUT15-33 was submitted to GenBank with provisional entry KU494019. Scale bar: number of substitutions per site
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig7: Phylogenetic analysis based on ORF2-7 nucleotide sequences of 52 PRRSV-1 strains and PRRSV-2 prototype VR2332 as an out-group. The PRRSV strain presented in this study is marked with a solid box and the associated sub-tree is highlighted with a dotted box. The tree was constructed with the software CLC Sequence Viewer 7.6 (CLCBIO, Aarhus, Denmark) using the neighbour joining method with the numbers at the nodes representing bootstrap values in % of 1000 replicates. The ORF2-7 sequence of AUT15-33 was submitted to GenBank with provisional entry KU494019. Scale bar: number of substitutions per site

Mentions: Initial phylogenetic analysis and identity calculations were carried out with NCBI’s Basic Local Alignment Search Tool for nucleotides (BLASTn). All PRRSV-1 strains with full ORF2-7 sequences deposited in GenBank as well as the two closest neighbours - as determined by NCBI BLASTn - were used to construct the phylogenetic trees. For ORF5 and ORF7, a nucleotide identity >99 % was found with the Austrian PRRSV strain ‘Acro’ (KT265737), which has been submitted to GenBank in July 2015 and very likely originates from the same PRRS outbreak. In the phylogenetic tree based on ORF7 both AUT15-33 and Acro cluster with several Croatian strains from 2012 [27], one of them (CRO_PRRSV_3, KF498723) is shown as a representative, but not with other current Austrian PRRSV sequences from 2013 and 2014 [26] (Fig. 5). The identity with the Croatian strains ranges from 94 to 95 %. Due to missing sequence data for the Croatian strains, the relatedness to them could not be investigated further. The phylogenetic tree built with ORF5 sequences shows the new Austrian isolate clustering with the Belgian strains 13 V091 and 08 V194 [28, 29] (Fig. 6). However, the nucleotide identity between these and AUT15-33 is only 86 %, the same as with the PRRSV-1 prototype strain Lelystad virus (LV). A similar pattern is seen in a phylogenetic tree based on a larger sequence part (3.2 kb) including the genome region coding for the structural proteins (ORF2-7) (Fig. 7). Here the identity of AUT15-33 to both Belgian strains mentioned above and to LV is 88 %.Fig. 5


Emergence of a virulent porcine reproductive and respiratory syndrome virus (PRRSV) 1 strain in Lower Austria
Phylogenetic analysis based on ORF2-7 nucleotide sequences of 52 PRRSV-1 strains and PRRSV-2 prototype VR2332 as an out-group. The PRRSV strain presented in this study is marked with a solid box and the associated sub-tree is highlighted with a dotted box. The tree was constructed with the software CLC Sequence Viewer 7.6 (CLCBIO, Aarhus, Denmark) using the neighbour joining method with the numbers at the nodes representing bootstrap values in % of 1000 replicates. The ORF2-7 sequence of AUT15-33 was submitted to GenBank with provisional entry KU494019. Scale bar: number of substitutions per site
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig7: Phylogenetic analysis based on ORF2-7 nucleotide sequences of 52 PRRSV-1 strains and PRRSV-2 prototype VR2332 as an out-group. The PRRSV strain presented in this study is marked with a solid box and the associated sub-tree is highlighted with a dotted box. The tree was constructed with the software CLC Sequence Viewer 7.6 (CLCBIO, Aarhus, Denmark) using the neighbour joining method with the numbers at the nodes representing bootstrap values in % of 1000 replicates. The ORF2-7 sequence of AUT15-33 was submitted to GenBank with provisional entry KU494019. Scale bar: number of substitutions per site
Mentions: Initial phylogenetic analysis and identity calculations were carried out with NCBI’s Basic Local Alignment Search Tool for nucleotides (BLASTn). All PRRSV-1 strains with full ORF2-7 sequences deposited in GenBank as well as the two closest neighbours - as determined by NCBI BLASTn - were used to construct the phylogenetic trees. For ORF5 and ORF7, a nucleotide identity >99 % was found with the Austrian PRRSV strain ‘Acro’ (KT265737), which has been submitted to GenBank in July 2015 and very likely originates from the same PRRS outbreak. In the phylogenetic tree based on ORF7 both AUT15-33 and Acro cluster with several Croatian strains from 2012 [27], one of them (CRO_PRRSV_3, KF498723) is shown as a representative, but not with other current Austrian PRRSV sequences from 2013 and 2014 [26] (Fig. 5). The identity with the Croatian strains ranges from 94 to 95 %. Due to missing sequence data for the Croatian strains, the relatedness to them could not be investigated further. The phylogenetic tree built with ORF5 sequences shows the new Austrian isolate clustering with the Belgian strains 13 V091 and 08 V194 [28, 29] (Fig. 6). However, the nucleotide identity between these and AUT15-33 is only 86 %, the same as with the PRRSV-1 prototype strain Lelystad virus (LV). A similar pattern is seen in a phylogenetic tree based on a larger sequence part (3.2 kb) including the genome region coding for the structural proteins (ORF2-7) (Fig. 7). Here the identity of AUT15-33 to both Belgian strains mentioned above and to LV is 88 %.Fig. 5

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