Lunney, Joan K., David A. Benfield and Raymond R R Rowland. "Porcine Reproductive and Respiratory Syndrome Virus: An update on an emerging and re-emerging viral disease of swine." Virus research (2010)

Virus Res. 2010 Oct 13. [Epub ahead of print]

Porcine Reproductive and Respiratory Syndrome Virus: An update on an emerging and re-emerging viral disease of swine.

Lunney JK, Benfield DA, Rowland RR.

Animal Parasitic Diseases Laboratory, BARC, ARS, USDA, Beltsville, MD 20705 USA.

Abstract

Recognized in the late 1980's in North America and Europe the syndrome that caused reproductive and respiratory problems in swine was initially called "Mystery Swine Disease" and is now termed "Porcine Reproductive and Respiratory Syndrome (PRRS)". In the early 1990's an arterivirus, referred to as PRRS virus (PRRSV), was determined to be the etiologic agent of this disease. Since then research has progressed substantially. Most recently "Porcine high fever disease" was reported in China starting in 2006 with PRRSV being a critical virus associated with high morbidity and mortality (20%) associated with this syndrome which in 2010 is still causing severe pathology in pigs in China, with spread to Vietnam and Cambodia. This volume contains a series of reviews that highlight the virus, its pathogenesis, epidemiology, immunology, vaccinology and host genetic control. This paper provides a brief historical review of PRRS and the associated PRRSV. It presents areas of research gaps that inhibit current progress towards PRRS elimination through production of effective vaccines and current plans for PRRS elimination or eradication programs. It is hoped that this discussion will stimulate further collaboration between researchers and swine veterinarians throughout the world to provide answers that enhance our understanding of PRRS and PRRSV in an effort to eliminate this economically important disease.

Copyright © 2010. Published by Elsevier B.V.

PMID: 20951175 [PubMed - as supplied by publisher]

Can J Vet Res. 2010 Jul;74(3):170-7.

Clinical signs and their association with herd demographics and porcine reproductive and respiratory syndrome (PRRS) control strategies in PRRS PCR-positive swine herds in Ontario.

Young B, Dewey C, Poljak Z, Rosendal T, Carman S.

Department of Population Medicine, University of Guelph, Guelph, Ontario. youngbet@missouri.edu

Abstract

The purposes of this study were to describe the clinical signs observed in PRRS positive herds during a porcine reproductive and respiratory syndrome (PRRS) outbreak in Ontario and to determine associations between these clinical signs and herd demographics and PRRS control strategies. All PRRS polymerase chain reaction-(PCR)-positive submissions to a diagnostic laboratory between September 1, 2004 and August 31, 2007 were identified (n = 1864). After meeting eligibility requirements and agreeing to voluntary study participation, producers from 455 of these submissions were surveyed for information on clinical signs observed in their herds, herd demographics, and PRRS control strategies used in their herds at the time that the PCR-positive samples were taken. Larger herd size was associated with an increased risk of reporting abortion, weakborn piglets, off-feed sows, and sow mortality in sow herds, and with an increased risk of reporting mortality in finishing herds. When disease control strategies were examined, use of a commercial PRRS vaccine in sows and gilts was associated with a decreased risk of reporting weakborn pigs and high pre-weaning mortality, while the use of serum inoculation in breeding animals was associated with an increased risk of reporting off-feed sows and sow mortality. Providing biofeedback of stillborn/mummified piglets, placenta or feces to gilts was associated with an increased risk of reporting respiratory disease and mortality in finishing pigs while all-in/all-out flow in farrowing rooms was associated with an increased risk of reporting sow mortality and weakborn piglets.

PMID: 20885840 [PubMed - in process]PMCID: PMC2896797Free PMC Article

Can J Vet Res. 2010 Jul;74(3):223-7.

Serodiagnosis of porcine reproductive and respiratory syndrome virus infection with the use of glycoprotein 5 antigens.

Pyo H, Seo J, Suh G, Kim K, Lee J, Kim T.

Department of Veterinary Medicine, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, Republic of Korea.

Abstract

Glycoprotein 5 (GP5) of porcine reproductive and respiratory syndrome virus (PRRSV) has been studied extensively as a target for vaccine development. This study evaluated the serodiagnostic application of PRRSV GP5 by enzyme-linked immunosorbent assay (ELISA). Two immunodominant peptides (VR #1 and VR #2) and two neutralizing ectodomain-containing peptides (Ecto #1 and Ecto #2), as well as recombinant GP5 (rGP5) as a control, were prepared. Serum from unvaccinated pigs was screened for the antibodies that bind to these peptide and protein antigens. The results were compared with those from a commercially available diagnostic ELISA kit (HerdChek), which uses the nucleocapsid (N) protein as an antigen. Only VR #1+#2 showed a result statistically similar to that of N protein. Ecto #1 and Ecto #2 had a lower sensitivity than VR #1+#2 and rGP5. The peptides and rGP5 showed significant associations with the N protein (P < 0.05 or 0.01), which suggests that GP5 may also be a candidate serodiagnostic antigen. Since antibodies against GP5 persist much longer than those against the N protein, GP5 itself and some of its fragments are thought to be good targets for serodiagnosis. In addition, the presence of antibodies against the PRRSV structural antigens showed significant antigen-dependent differences.

PMID: 20885848 [PubMed - in process]PMCID: PMC2896805Free PMC Article

Clin Vaccine Immunol. 2010 Oct 6. [Epub ahead of print]

Porcine reproductive and respiratory syndrome virus (PRRSV) infection at the time of porcine circovirus type 2 (PCV2) vaccination has no impact on vaccine efficacy.

Sinha A, Shen HG, Schalk S, Beach NM, Huang YW, Halbur PG, Meng XJ, Opriessnig T.

Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA; Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA.

Abstract

Several porcine circovirus type 2 (PCV2) vaccines are now commercially available and have been shown to be effective at decreasing the occurrence of porcine circovirus associated disease (PCVAD). Many herds are coinfected with PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV). Some producers and veterinarians are concerned that if pigs are vaccinated for PCV2 at or near the time they typically are infected with PRRSV, the efficacy of the PCV2 vaccine will be compromised. The impact of PRRSV on PCV2 vaccination is unclear and has not been investigated under controlled conditions. The objective of the present study was to determine whether the presence of PRRSV viremia has an effect on the efficacy of commercial PCV2 vaccinations. Three-week-old PCV2-negative conventional pigs with passively-derived anti-PCV2-antibodies were either vaccinated with one of three commercial PCV2 vaccines or left non-vaccinated. A portion of the pigs were infected with PRRSV one week prior to PCV2 vaccination. To determine vaccine efficacy, a PCV2 challenge was conducted at 8 weeks of age. PCV2 vaccination regardless of PRRSV infection status at the time of vaccination was similarly effective in inducing an anti-PCV2-IgG response in the presence of maternally-derived immunity and in protecting the pigs from PCV2 challenge as determined by reduction in PCV2 viremia and reduction of prevalence and amount of PCV2 antigen in lymphoid tissues compared to non-vaccinated pigs. The results indicate that acute PRRSV infection at the time of PCV2 vaccination has no adverse effect on PCV2 vaccine efficacy.

PMID: 20926694 [PubMed - as supplied by publisher]

Sinha, A., et al. "Porcine reproductive and respiratory syndrome virus (PRRSV) infection at the time of porcine 

circovirus type 2 (PCV2) vaccination has no impact on vaccine efficacy." Clinical and vaccine immunology (2010