This gap in knowledge complicates the identification of the source of outbreaks, which is crucial as the most important PRRSV problems in Austria occur as a consequence of (re-) introduction into formerly free herds. The lack of published full-length sequences is exemplified by the situation in Austria, where the limited data on current strains consists solely of ORF5 or ORF7 sequences. For these reasons, the use of further methodologies for genetic subtyping has been suggested, such as whole genome sequencing. Phylogenetic analysis based on ORF5 and ORF7 may also lead to different subtyping of PRRSV-1 strains. However, the analysis is limited as these short genomic sequences might be subject to recombination and immunological selection pressure. Nucleotide sequences of ORF5 (603–606 bp) and ORF7 (372–387 bp) are widely used for phylogenetic studies. The major structural proteins GP5, membrane protein (M) and N protein are encoded by ORF5–7. ORF2–4 encode the minor structural proteins, including glycoprotein (GP) 2, 3 and 4, which form a hetero-trimer that is believed to be involved in virus entry. ORF1a and 1b constitute over 75% of the viral genome and encode two polyproteins, which are cleaved into at least 14 nonstructural proteins (nsp) that are responsible for genome replication and transcription. The 5′-capped and 3′-polyadenylated genome of PRRSV is about 15 kb in length and contains ten open reading frames (ORF). PRRSV is a small, enveloped virus with a single-stranded positive-sense RNA genome that belongs to the family Arteriviridae, order Nidovirales. Therefore, three subtypes have been proposed for PRRSV-1 based the size of the nucleocapsid protein (N): pan-European subtype 1 and Eastern European subtypes 2 and 3. Due to high mutation and recombination rates, variability is also high within the genotypes, especially in type 1. The two genotypes share only about 60% identity at the nucleotide level. This strain, Lelystad virus (LV), is regarded as the prototype strain of European PRRSV type 1 (PRRSV-1), whereas VR2332 represents the North American PRRSV type 2 (PRRSV-2). The causative agent, PRRSV, was first isolated in 1991 in the Netherlands. The disease emerged in the late eighties in North America, with the first outbreaks in Europe recorded in 1990. It is the etiological agent of porcine reproductive and respiratory syndrome (PRRS), which is characterized by respiratory disorders as well as by growth retardation in growing pigs and reproductive failure in late gestation sows. Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important pathogens in the swine industry worldwide. This stresses the necessity for a more detailed analysis of current PRRSV strains in Europe beyond the determination of short ORF5 and ORF7 sequences. Taken together, the genetic and biological characterization of two novel Austrian PRRSV field isolates revealed similarities to East Asian strains. Both Austrian isolates caused similar lung lesions but only pigs infected with AUT14-440 developed clear clinical signs of infection. In addition, this isolate showed exceptional deletions in nonstructural protein 2, in the overlapping region of glycoprotein 3 and 4 and in the 3′ untranslated region. Remarkably, AUT14-440 infected the simian cell line MARC-145 without prior adaptation. Phylogenetic analysis revealed that the strains belong to European genotype 1 subtype 1 and form a cluster together with a South Korean strain. ![]() We determined full-length genome sequences of two Austrian field isolates (AUT13-883 and AUT14-440) from recent PRRSV outbreaks and of a related German isolate (GER09-613). However, little is known about current PRRSV strains and epidemiology. Due to Austria’s central location in Europe, a large number of animals are transported through the country. ![]() Porcine reproductive and respiratory syndrome virus (PRRSV) causes major problems for the swine industry worldwide.
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