Abstract
Porcine reproductive and respiratory syndrome virus is the cause of reproductive failure in sows and respiratory disease in young pigs, which has been considered as one of the most costly diseases to the worldwide pig industry for almost 30 years. This study used microarray-based transcriptomic analysis of PBMCs from experimentally infected pigs to explore the patterns of immune dysregulation after infection with two East European PRRSV strains from subtype 2 (BOR and ILI) in comparison to a Danish subtype 1 strain (DAN). Transcriptional profiles were determined at day 7 post infection in three tested groups of pigs and analysed in comparison with the expression profile of control group. Microarray analysis revealed differential regulation (> 1.5-fold change) of 4253 and 7335 genes in groups infected with BOR and ILI strains, respectively, and of 12518 genes in pigs infected with Danish strain. Subtype 2 PRRSV strains showed greater induction of many genes, especially those involved in innate immunity, such as interferon stimulated antiviral genes and inflammatory markers. Functional analysis of the microarray data revealed a significant up-regulation of genes involved in processes such as acute phase response, granulocyte and agranulocyte adhesion and diapedesis, as well as down-regulation of genes enrolled in pathways engaged in protein synthesis, cell division, as well as B and T cell signaling. This study provided an insight into the host response to three different PRRSV strains at a molecular level and demonstrated variability between strains of different pathogenicity level.
Highlights
Porcine reproductive and respiratory syndrome (PRRS) is a viral disease of significant economic impact on a swine industry worldwide
The pigs used in the study originated from a high health pig herd maintained by the Institute and were free from infections with the following pathogens: encephalomyocarditis virus, hepatitis E virus, porcine circovirus type 1 and type 2 viruses, porcine cytomegalovirus, porcine epidemic diarrhoea virus, porcine parvovirus type 1, porcine respiratory coronavirus, PRRS virus (PRRSV) Type 1 and Type 2, influenza A virus, transmissible gastroenteritis virus, Actinobacillus pleuropneumoniae, Bordetella bronchiseptica, Brachyspira hyodysenteriae, Brachyspira pilosicoli and Brucella spp, using in-house standard diagnostic methods
Three groups of 8-week-old pigs were infected with a PRRSV Type 1 strains including subtype 1 strain 18,794 (DAN) isolated in 1993 in Denmark [19], a Russian isolate ILI6 (ILI) and a Belarusian isolate BOR59 (BOR) from 2009, each classified as subtype 2 strain based on ORF5 sequence, respectively
Summary
Porcine reproductive and respiratory syndrome (PRRS) is a viral disease of significant economic impact on a swine industry worldwide. The disease manifests by reproductive disorders in sows and respiratory lesions and poor growth performance in growing pigs. The etiological agent of the disease, PRRS virus (PRRSV) is an enveloped, positive-sense single-strand RNA virus classified in the order Nidovirales, family Arteriviridae. Type 1 and Type 2, sharing approximately 60% of genetic similarity were described [1]. A newly proposed classification denotes both types as different species within Arteriviridae family (https://talk.ictvonline.org/taxonomy/). Type 1 can be further divided into at least four genetic subtypes, namely Pan-European subtype 1 and subtypes 2, 3 and 4 represented by strains circulating in Eastern European countries [2]. Gathering evidences suggest the existence of additional
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