Shi, Mang, et al. "Molecular Epidemiology of PRRSV: A Phylogenetic Perspective." Virus research (2010)

Virus Res. 2010 Sep 10. [Epub ahead of print]

Molecular Epidemiology of PRRSV: A Phylogenetic Perspective.

Shi M, Lam TT, Hon CC, Hui RK, Faaberg KS, Wennblom T, Murtaugh MP, Stadejek T, Leung FC.

School of Biological Sciences, The University of Hong Kong, Hong Kong, China.

Abstract

Since its first discovery two decades ago, porcine reproductive and respiratory syndrome virus (PRRSV) has been the subject of intensive research due to its huge impact on the worldwide swine industry. Thanks to the phylogenetic analyses, much has been learned concerning the genetic diversity and evolution history of the virus. In this review, we focused on the evolutionary and epidemiological aspects of PRRSV from a phylogenetic perspective. We first described the diversity and transmission dynamics of Type 1 and 2 PRRSV, respectively. Then, we focused on the more ancient evolutionary history of PRRSV: the time of onset of all existing PRRSV and an original hypothesis were discussed. Finally, we summarized the results from previous recombination studies to assess the potential impact of recombination on the virus epidemiology.

PMID: 20837072 [PubMed - as supplied by publisher]

Corzo, Cesar A., et al. "Control and elimination of porcine reproductive and respiratory syndrome virus." Virus research (2010)

Virus Res. 2010 Sep 10. [Epub ahead of print]

Control and elimination of porcine reproductive and respiratory syndrome virus.

Corzo CA, Mondaca E, Wayne S, Torremorell M, Dee S, Davies P, Morrison RB.

Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, Saint Paul, Minnesota.

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSv) can have a significant, economic impact on swine herds due to reproductive failure, preweaning mortality and reduced, performance in growing pigs. Control at the farm level is pursued through different management, procedures (e.g. pig flow, gilt acclimation, vaccination). PRRSv is commonly eliminated from sow, herds by a procedure called herd closure whereby the herd is closed to new introductions for a period, of time during which resident virus dies out. However, despite thorough application of biosecurity, procedures, many herds become re-infected from virus that is present in the area. Consequently, some, producers and veterinarians are considering a voluntary regional program to involve all herds present, within an area. Such a program was initiated in Stevens County in west central Minnesota in 2004., PRRSv has been eliminated from most sites within the region and the area involved has expanded to, include adjacent counties. The program has been relatively successful and reflects local leadership, a, cooperative spirit, and a will to eliminate virus from the region.

PMID: 20837071 [PubMed - as supplied by publisher]

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The interaction between PRRSV and the late gestation pig fetus.

Rowland, Raymond R R. "The interaction between PRRSV and the late gestation pig fetus." Virus research (2010)

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) crosses the placenta during late gestation and productively infects the fetus. Virus replication and cytokine responses were measured in tissues of fetuses recovered at 109 to 112 days of gestation, just prior to parturition. At the time of recovery, gross anatomical abnormalities were evident in both infected and non- infected fetuses from the infected dams. Virus isolation and immunohistochemistry identified the thymus as the primary site of virus replication. Steady state RT-PCR amplification of inflammatory, Th1 and Th2 cytokines, showed elevated IFN-γ and TNF-α mRNAs in tissues from infected fetuses, which corresponded to elevated cytokine proteins in serum but not amniotic fluid. Further evidence for induction of immunity was found in the hyperplastic response of lymph nodes, which included the development of germinal centers occupied CDw75+ B cells. Collectively, these data support the notion that the immunocompetent fetus is capable of initiating an antiviral response, which is compartmentalized within the infected fetus. Furthermore, fetal pathology may not be a direct result of virus replication in the fetus.

Key words. Porcine reproductive and respiratory syndrome virus (PRRSV), congenital infection, tumor necrosis factor-α (TNF-α ), interferon-γ (IFN-γ)