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United States Department of Agriculture

Agricultural Research Service

Title: Detection of Porcine Reproductive and Respiratory Syndrome Virus in Semen and Serum of Boars During the First Six Days after Inoculation

Authors
item Reicks, Darwin - SWINE VET CTR, MINNESOTA
item Munoz-Zanzi, Claudia - UNIVERSITY OF MINNESOTA
item Mengeling, William - IOWA STATE UNIVERSITY
item Christopher-Hennings, Jane - SOUTH DAKOTA STATE UNIV
item Lager, Kelly
item Polson, Dale - BOEHRINGER INGELHEIM VETM
item Dee, Scott - UNIVERSITY OF MINNESOTA
item Rossow, Kurt - UNIVERSITY OF MINNESOTA

Submitted to: Swine Health and Production
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 14, 2005
Publication Date: January 1, 2006
Citation: Reicks, D.L., Munoz-Zanzi, C., Mengeling, W., Christopher-Hennings, J., Lager, K., Polson, D., Dee, S., Rossow, K. 2006. Detection of porcine reproductive and respiratory syndrome virus in semen and serum of boars during the first six days after inoculation. Journal of Swine Health and Production. 14(1):35-41.

Interpretive Summary: Porcine reproductive and respiratory syndrome (PRRS) is the number one disease problem faced by pork producers in the US. It is caused by the PRRS virus (PRRSV) and this virus can be shed in the semen of infected boars. Transmission of PRRSV by way of contaminated semen is a significant problem for the swine industry and it is critical that the most efficient methods for PRRSV detection in semen or infected boars are used. The objective of this study was to find the most sensitive method to detect an acute PRRSV infection in boars by comparing tests on tissue samples and different sampling techniques. Polymerase chain reaction (PCR) tests designed for PRRSV were used to test for virus in serum and semen. The effect of pooling samples together and then testing for virus and the possible association between rectal temperature and detection of PRRSV in serum by PCR were evaluated. Forty mature boars (four groups of 10) were inoculated intranasally with PRRSV strain MN 30-100. Serum and semen samples were collected on a rotating basis from one group every 12 hours for 6 days and tested for PRRSV by PCR. Rectal temperatures were recorded for all 40 boars at 12-hour intervals. Serum samples became PCR-positive before semen samples. During the first 6 days after inoculation, serum was PRRSV-positive in 36 of 40 boars, and semen was PRRSV-positive in four of 40 boars. Results were inconsistent when a positive semen sample was pooled with negative semen. Elevated rectal temperature was not associated with PCR-positive serum or semen results. Under the conditions of this study, PCR is more sensitive and detects PRRSV-infected boars earlier in serum than in semen. Pooling of positive semen samples provides variable PCR results. Rectal temperatures are not correlated with PCR-positive results. Since virus was found sooner in serum samples when compared to semen samples, better sampling techniques are needed to more easily obtain serum samples from boars for frequent PRRSV testing of boars.

Technical Abstract: Porcine reproductive and respiratory syndrome (PRRS) is the number one disease problem faced by pork producers in the US. It is caused by the PRRS virus (PRRSV) and this virus can be shed in the semen of infected boars. Transmission of PRRSV by way of contaminated semen is a significant problem for the swine industry and it is critical that the most efficient methods for PRRSV detection are used. The objective of this study was to find the most sensitive method to detect an acute PRRSV infection in boars by comparing tests on tissue samples and different sampling techniques. Polymerase chain reaction (PCR) tests designed for PRRSV were used to test for virus in serum and semen. The effect of pooling samples together and then testing for virus and the possible association between rectal temperature and detection of PRRSV in serum by PCR were evaluated. Forty mature boars (four groups of 10) were inoculated intranasally with PRRSV strain MN 30-100. Serum and semen samples were collected on a rotating basis from one group every 12 hours for 6 days and tested for PRRSV by PCR. Rectal temperatures were recorded for all 40 boars at 12-hour intervals. Serum samples became PCR-positive before semen samples. During the first 6 days after inoculation, serum was PRRSV-positive in 36 of 40 boars, and semen was PRRSV-positive in four of 40 boars. Median time to detection was 36 and 72 hours for nested PCR and Taqman PCR, respectively. Results were inconsistent when a positive semen sample was pooled with negative semen. Elevated rectal temperature was not associated with PCR-positive serum or semen results. Under the conditions of this study, PCR is more sensitive and detects PRRSV-infected boars earlier in serum than in semen. Pooling of positive semen samples provides variable PCR results. Rectal temperatures are not correlated with PCR-positive results. Since virus was found sooner in serum samples when compared to semen samples, better sampling techniques are needed to more easily obtain serum samples from boars for frequent PRRSV testing of boars.

Last Modified: 10/24/2014
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