Systematic review and meta-analysis on the diagnostic accuracy of various detection methods for porcine reproductive and respiratory syndrome virus

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Introduction: Porcine reproductive and respiratory syndrome virus (PRRSV) causes respiratory disease in piglets and reproductive disease in sows. Piglet and fetal serum thyroid hormone (i.e., T3 and T4) levels decrease rapidly in response to Porcine reproductive and respiratory syndrome virus infection. However, the genetic control of T3 and T4 levels during infection is not completely understood. Our objective was to estimate genetic parameters and identify quantitative trait loci (QTL) for absolute T3 and/or T4 levels of piglets and fetuses challenged with Porcine reproductive and respiratory syndrome virus. Methods: Sera from 5-week-old pigs (N = 1792) at 11 days post inoculation (DPI) with Porcine reproductive and respiratory syndrome virus were assayed for T3 levels (piglet_T3). Sera from fetuses (N = 1,267) at 12 or 21days post maternal inoculation (DPMI) with Porcine reproductive and respiratory syndrome virus of sows (N = 145) in late gestation were assayed for T3 (fetal_T3) and T4 (fetal_T4) levels. Animals were genotyped using 60K Illumina or 650K Affymetrix single nucleotide polymorphism (SNP) panels. Heritabilities, phenotypic correlations, and genetic correlations were estimated using ASREML; genome wide association studies were performed for each trait separately using Julia for Whole-genome Analysis Software (JWAS). Results: All three traits were low to moderately heritable (10%-16%). Phenotypic and genetic correlations of piglet_T3 levels with weight gain (0-42 DPI) were 0.26 ± 0.03 and 0.67 ± 0.14, respectively. Nine significant quantitative trait loci were identified for piglet_T3, on Sus scrofa chromosomes (SSC) 3, 4, 5, 6, 7, 14, 15, and 17, and collectively explaining 30% of the genetic variation (GV), with the largest quantitative trait loci identified on SSC5, explaining 15% of the genetic variation. Three significant quantitative trait loci were identified for fetal_T3 on SSC1 and SSC4, which collectively explained 10% of the genetic variation. Five significant quantitative trait loci were identified for fetal_T4 on SSC1, 6, 10, 13, and 15, which collectively explained 14% of the genetic variation. Several putative immune-related candidate genes were identified, including CD247, IRF8, and MAPK8. Discussion: Thyroid hormone levels following Porcine reproductive and respiratory syndrome virus infection were heritable and had positive genetic correlations with growth rate. Multiple quantitative trait loci with moderate effects were identified for T3 and T4 levels during challenge with Porcine reproductive and respiratory syndrome virus and candidate genes were identified, including several immune-related genes. These results advance our understanding of growth effects of both piglet and fetal response to Porcine reproductive and respiratory syndrome virus infection, revealing factors associated with genomic control of host resilience.

The study assessed the economic impact of porcine reproductive and respiratory syndrome virus on pork production in Delta South Senatorial, District. A multi-stage sampling procedure was used to select 83 pork producers for the study. Questionnaire was used as the instrument for data collection. Data collected were analyzed using frequency, percentage, mean and standard deviation. The findings of the study showed that most of the pork producers in the study area were males, 57.0% were married; 47.3% of the pork producers had 6-20 years of pork production experience and majority of pork producers had relatively high level of education. The results also revealed that porcine reproductive and respiratory syndrome virus has negative economic impact (P<0.05) on pork production in Delta South Senatorial District. It was found out that there is no significant (P>0.05) difference between the socio-economic characteristics of the respondents on the economic impact of porcine reproductive and respiratory syndrome virus on pork production in Delta South Senatorial District. From the findings of this study, porcine reproductive and respiratory syndrome virus is associated with illness which causes reduction in growth rates and mortalities in all ages of pigs which leads to economic losses. It can therefore be recommended among others that the three tiers of government should organize public enlightenment programme to create awareness on measures to control porcine reproductive and respiratory syndrome virus against pork production.

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Porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae are account as economically important pathogens in swine business worldwide. The studies of these two pathogens in Thailand were restricted on domestic pigs in swine industry and the status of these pathogens in wild boars is currently not available. This cross-sectional study aimed at estimating the seroprevalence of antibodies to these agents in captive wild boars. Fifty-two serum samples were collected from wild boars reared in three different types of captive settings including a commercial wild boar farm, a wildlife breeding research station and a zoo. All serum samples were examined for antibodies to porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae by ELISA methods. The results revealed that the highest true prevalence of both pathogens was found in sera derived from wild boars in wildlife breeding research station at 69 and 66% for porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae respectively. This study is the first to reveal seroprevalence of antibodies against porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniaein wild boar populations in Thailand. More detailed investigations are critically needed.

In this assay, we developed and evaluated a multiplex PCR (mPCR) for its ability in detecting multiple infections of swine simultaneously. Four pairs of primers were used to detect five viruses. Specific primers were designed for classical swine fever virus (CSFV), African swine fever virus (ASFV) and pseudorabies (PRV). A pair of primers was designed prudently for two different types of porcine reproductive and respiratory syndrome virus that respectively were porcine reproductive and respiratory syndrome virus (PRRSV), highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV). The detection limits of the mPCR were 1.09 × 10⁴, 1.50 × 10³, 2.10 × 10³, 1.30 × 10³ and 8.97 × 10² copies/reaction for CSFV, ASFV, HP-PRRSV, PRRSV and PRV, respectively. A total of 49 clinical specimens were tested by the mPCR, and the result showed that co-infection by two or three viruses was 51%. In conclusion, the PCR is a useful tool for clinical diagnosis of not only single infections but also mixed infections in swines.

The bacterially expressed nucleocapsid (N) protein of porcine respiratory and reproductive syndrome virus (PRRSV) was used as immunogen to generate a rabbit-derived polyclonal antibody. The immunoreactivity of the protein to the antibody was confirmed by Western blot analysis. Using PRRSV, transmissible gastroenteritis virus, porcine epidemic diarrhea virus, pseudorabies virus, and avian infectious bronchitis virus as coating antigens, a virus-based ELISA was established. The polyclonal antibody against PRRSV N protein used as a diagnostic agent was capable of differentiating PRRSV from the other viruses.

Purification of porcine reproductive and respiratory syndrome virus from cell culture using ultrafiltration and heparin affinity chromatography

Extract In the paper by EJ Neumann, RS Morris and M Sujau published in the New Zealand Veterinary Journal 55, 326–336, 2007, entitled, “Analysis of the risk of introduction and spread of porcine reproductive and respiratory syndrome virus through importation of raw pigmeat into New Zealand”, the authors sought to analyse the risk of the introduction and spread of porcine reproductive and respiratory syndrome (PRRS) virus through importation of raw pigmeat. As cautioned by the International Committee of the World Organisation for Animal Health (OIE), any epidemiological model ultimately depends for its validity on the accuracy and completeness of the data underpinning it.

Unraveling the contact patterns and network structure of pig shipments in the United States and its association with porcine reproductive and respiratory syndrome virus (PRRSV) outbreaks

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most relevant porcine pathogens worldwide. Active control of the disease relies on modified live virus vaccines (MLVs), as most inactivated vaccines provide very limited protection. Neutralizing antibodies occur late in infection; therefore, CD8+ T cells are considered important correlates of protection and are a frequent focus of investigation. Our aim was to identify viral peptides naturally bound by the class I major histocompatibility complex (MHC-I) and to confirm their ability to stimulate CD8+ T cells. For this purpose, we immunoprecipitated MHC-I/peptide complexes of PRRSV (strain AUT15-33) -infected cells (SLA-I Lr-Hp 35.0/24 mod) to isolate the viral epitopes and analyzed them with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Furthermore, we employed these identified peptides to stimulate peripheral blood mononuclear cells (PBMCs) of previously PRRSV-infected pigs and measured the PRRSV-specific CD8+ T-cell response with an intracellular cytokine staining (ICS). Our data revealed that PRRSV non-structural proteins (NSPs), encoded in open reading frame 1a and 1b (ORF1), present the major source of MHC-I-presented peptides. Additionally, we show that our identified epitopes are able to trigger IFNγ responses in vitro. These findings are a basis for understanding the proteasomal degradation of PRRSV proteins, the cellular ability to display them via MHC-I, and their potential to restimulate CD8+ T cells.

The family Arteriviridae presently includes a single genus Arterivirus. This genus includes four species as the taxonomic homes for equine arteritis virus (EAV), lactate dehydrogenase-elevating virus (LDV), porcine respiratory and reproductive syndrome virus (PRRSV), and simian hemorrhagic fever virus (SHFV), respectively. A revision of this classification is urgently needed to accommodate the recent description of eleven highly divergent simian arteriviruses in diverse African nonhuman primates, one novel arterivirus in an African forest giant pouched rat, and a novel arterivirus in common brushtails in New Zealand. In addition, the current arterivirus nomenclature is not in accordance with the most recent version of the International Code of Virus Classification and Nomenclature. Here we outline an updated, amended, and improved arterivirus taxonomy based on current data. Taxon-specific sequence cut-offs are established relying on a newly established open reading frame 1b phylogeny and pairwise sequence comparison (PASC) of coding-complete arterivirus genomes. As a result, the current genus Arterivirus is replaced by five genera: Equartevirus (for EAV), Rodartevirus (LDV + PRRSV), Simartevirus (SHFV + simian arteriviruses), Nesartevirus (for the arterivirus from forest giant pouched rats), and Dipartevirus (common brushtail arterivirus). The current species Porcine reproductive and respiratory syndrome virus is divided into two species to accommodate the clear divergence of the European and American “types” of PRRSV, both of which now receive virus status. The current species Simian hemorrhagic fever virus is divided into nine species to accommodate the twelve known simian arteriviruses. Non-Latinized binomial species names are introduced to replace all current species names to clearly differentiate them from virus names, which remain largely unchanged.

Porcine respiratory and reproductive syndrome virus (PRRSV) causes an economically important disease affecting commercial pork production worldwide. NADC34-like PRRSV has had a strong impact on the U.S. and Peruvian pig industries in recent years and also emerged in northeastern China in 2017. However, the endemic status of NADC34-like PRRSV in China is unclear. In this study, we examined 650 tissue samples collected from 16 Provinces in China from 2018 to 2019. Six NADC34-like PRRSV strains were detected in samples from three Provinces, and the complete genomes of four of these strains were sequenced. Phylogenetic analysis showed that these novel PRRSV strains belong to sublineage 1.5 (or NADC34-like PRRSV), forming two groups in China. Sequence alignment suggested that these novel strains share the same 100-aa deletion in the Nsp2 protein that was identified in IA/2014/NADC34 isolated from the United States in 2014. Recombination analysis revealed that five of eight complete genome sequences are derived from recombination between IA/2014/NADC34 and ISU30 or NADC30. The number and distribution of NADC34-like PRRSVs is increasing in China. Importantly, compared with the currently endemic strain NADC30-like PRRSV, NADC34-like PRRSV has the potential to be an endemic strain in China. This study will help us understand the epidemic status of NADC34-like PRRSV in China and provide data for further monitoring this type of PRRSV in China.

Porcine reproductive and respiratory syndrome virus (PRRSv) interaction with Haemophilus parasuis

Re-emerging of porcine respiratory and reproductive syndrome virus (lineage 3) and increased pathogenicity after genomic recombination with vaccine variant