Comparison of RNA extraction and real-time reverse transcription polymerase chain reaction methods for the detection of Porcine reproductive and respiratory syndrome virus in porcine oral fluid specimens

Chittick W A, Stensland W R, Prickett J R, Strait E L, Harmon K, Yoon K, Wang C, Zimmerman J. 2011. Comparison of RNA extraction and real-time reverse transcription polymerase chain reaction methods for the detection of Porcine reproductive and respiratory syndrome virus in porcine oral fluid specimens. Journal of veterinary diagnostic investigation 23(2):248-253.

Abstract

The objective of the current study was to evaluate various RNA extraction and polymerase chain reaction (PCR) protocols for the detection of Porcine reproductive and respiratory syndrome virus (PRRSV) in porcine oral fluids. Extraction protocols were selected based on ease of use and compatibility with high-throughput, automated systems. The results showed marked differences among extraction protocols, PCR protocols, and combinations thereof in detecting PRRSV in the oral fluid matrix. An important finding was that PCR reactions were partially inhibited by unknown factors in the oral fluid matrix and that inhibition was reduced by use of a higher concentration of PCR enzymes. The results suggest that further optimization of PCR assays for porcine oral fluids is needed and that laboratories should not assume that methods optimized for detection of virus in serum will perform equally with porcine oral fluids.

PMID: 21398443 [PubMed - in process]

Pigs resistant to diseases! Are we ready????

Fan Bin, Onteru S K, Du Z, Garrick D J, Stalder K J, Rothschild M F. 2011. Genome-wide association study identifies Loci for body composition and structural soundness traits in pigs. PLoS ONE 6(2):e14726-e14726.

uouououou! hold on! What does this paper has to do with "Field PRRS" blog?


Well... it is a genome-wide study with pig genome (yes, all - or almost all - pig genes has been mapped and their functions are being studied). This will allow researchers (and genetic companies??) to find out genes associated with specific diseases resistance. Will this research take 1, 2, 3, 10 years to happen? We obviously don't know but let's hope it is soon.

Here is the abstract of this study - enjoy it:

Abstract

BACKGROUND: The recent completion of the swine genome sequencing project and development of a high density porcine SNP array has made genome-wide association (GWA) studies feasible in pigs.

METHODOLOGY/PRINCIPAL FINDINGS: Using Illumina's PorcineSNP60 BeadChip, we performed a pilot GWA study in 820 commercial female pigs phenotyped for backfat, loin muscle area, body conformation in addition to feet and leg (FL) structural soundness traits. A total of 51,385 SNPs were jointly fitted using Bayesian techniques as random effects in a mixture model that assumed a known large proportion (99.5%) of SNPs had zero effect. SNP annotations were implemented through the Sus scrofa Build 9 available from pig Ensembl. We discovered a number of candidate chromosomal regions, and some of them corresponded to QTL regions previously reported. We not only have identified some well-known candidate genes for the traits of interest, such as MC4R (for backfat) and IGF2 (for loin muscle area), but also obtained novel promising genes, including CHCHD3 (for backfat), BMP2 (for loin muscle area, body size and several FL structure traits), and some HOXA family genes (for overall leg action). The candidate regions responsible for body conformation and FL structure soundness did not overlap greatly which implied that these traits were controlled by different genes. Functional clustering analyses classified the genes into categories related to bone and cartilage development, muscle growth and development or the insulin pathway suggesting the traits are regulated by common pathways or gene networks that exert roles at different spatial and temporal stages.

CONCLUSIONS/SIGNIFICANCE: This study is one of the earliest GWA reports on important quantitative traits in pigs, and the findings will contribute to the further biological function analysis of the identified candidate genes and potential utilization of them in marker assisted selection.

Host inhibits replication of European porcine reproductive and respiratory syndrome virus in macrophages by altering differential regulation of type-I interferon transcriptional response

Ait-Ali T, Wilson A D, Carr W, Westcott D G, Frossard J, Mellencamp M A, Mouzaki D, Matika O, Waddington D, Drew T W, Bishop S C, Archibald A L. 2011. Host inhibits replication of European porcine reproductive and respiratory syndrome virus in macrophages by altering differential regulation of type-I interferon transcriptional response. Immunogenetics.

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is an infectious disease caused by a positive RNA strand arterivirus. PRRS virus (PRRSV) interacts primarily with lung macrophages. Little is known how the virus subverts the innate immune response to initiate its replication in alveolar macrophages. Large-scale transcriptional responses of macrophages with different levels of susceptibility to PRRSV infection were compared over 30 h of infection. This study demonstrates a rapid and intense host transcriptional remodelling during the early phase of the replication of the virus which correlates with transient repression of type-I interferon transcript as early as 8 h post-infection. These results support the suggestion from previous studies that host innate immune response inhibits replication of European porcine reproductive and respiratory syndrome virus in macrophages by altering differential regulation of type-I interferon transcriptional response.

Keywords  Swine – Innate immunity – Alveolar macrophage – PRRSV – Interferon response