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United States Department of Agriculture

Agricultural Research Service

Research Project: SWINE VIRAL DISEASES PATHOGENESIS AND IMMUNOLOGY Title: Pathogenesis and Transmission of Feral Swine Pseudorabies Virus Isolates in Domestic Pigs

Authors
item Zanella, Eraldo -
item Lager, Kelly
item Kehrli Jr, Marcus
item Miller, Laura
item Swenson, Sabrina -
item Bigelow, Troy -

Submitted to: Research in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 6, 2011
Publication Date: N/A

Interpretive Summary: Pseudorabies is one of the oldest described swine diseases recognized as reproductive failure and respiratory and central nervous system disease. It is caused by pseudorabies virus (PRV). The development of vaccines and blood tests that allow the differentiation of vaccinated pigs from naturally infected pigs has greatly reduced the economic losses caused by PRV and enabled some countries to eradicate the disease from domestic swine. One weakness in PRV control and eradication programs is PRV infection of feral swine and wild boar that can serve as a reservoir for PRV. In the United States the feral swine population has been steadily increasing with feral pigs having been reported in 38 of the 50 states. Repeated testing in many states has found PRV-positive animals indicating a wide distribution in feral swine. This wildlife reservoir has been responsible for sporadic infections of domestic swine and is a continual threat to the PRV-free status of the US swine industry. This paper reports studies evaluating the effect of feral swine PRV isolates on young domestic pigs, the spread of these viruses to direct contact pigs, and the antibody response in the direct-contact pigs. Under the conditions of the study reported here, PRV isolated from feral swine and from a panther induced clinical disease in young pigs, easily transmitted from infected pigs to contact pigs, and produced an antibody response that could be detected for at least 17 weeks. The antibody response supports the current use of blood tests in the PRV surveillance program to check domestic swine at the time of slaughter for PRV infection.

Technical Abstract: Pseudorabies is one of the oldest described swine diseases recognized as reproductive failure, and respiratory and central nervous system disease. It is caused by pseudorabies virus (PRV). The development of vaccines and serologic tests that allow the differentiation of vaccinated pigs from naturally infected pigs has greatly reduced the economic losses caused by PRV and enabled some countries to eradicate the disease from domestic swine. One weakness in PRV control and eradication programs is PRV infection of feral swine and wild boar that can serve as a reservoir for PRV. In the United States the feral swine population has been steadily increasing with feral pigs having been reported in 37 of the 50 states. Repeated testing in many states has found PRV-positive animals indicating a wide distribution in feral swine. This wildlife reservoir has been responsible for sporadic infections of domestic swine and is a continual threat to the PRV-free status of the US swine industry. This paper reports studies evaluating the effect of feral swine PRV isolates on young domestic pigs, the spread of these viruses to direct contact pigs, and the antibody response in the direct-contact pigs. Under the conditions of the study reported here, PRV isolated from feral swine and from a panther induced clinical disease in young pigs, easily transmitted from infected pigs to contact pigs, and produced an antibody response that could be detected for at least 17 weeks. The antibody response supports the current use of antibody tests in the PRV surveillance program to check domestic swine at the time of slaughter for PRV infection. When compared to a well-characterized domestic swine PRV isolate, ISUVDL4892, the severity of disease following infection with the feral swine viruses was attenuated. In addition, the results of this study support the observation by others of an age-related susceptibility to PRV with younger pigs being more affected clinically than older animals.

Last Modified: 10/26/2014
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