Experiences with tonsil biopsy as an antemortem diagnostic test for detecting porcine reproductive and respiratory syndrome virus infection in breeding swine
Mike D. Bierk, DVM; Scott A. Dee, DVM, PhD; Kurt D. Rossow, DVM, PhD; James E. Collins, DVM, PhD; Maria Isabelle Guedes, DVM; Thomas W. Molitor, MS, PhD
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Objective: To summarize results obtained with antemortem tonsil biopsy, and compare them to those obtained during traditional postmortem sampling, for detecting porcine reproductive and respiratory syndrome virus (PRRSV) infection in breeding swine.
Methods: Tonsil biopsies were collected from 42 sows in a 1500-sow breeding herd known to be chronically infected with PRRSV. Animals were euthanized after the biopsy, and tissues were collected using routine necropsy procedures. Two sows that originated from a PRRSV-negative farm were inoculated by the intranasal (IN) route with a total dose of 102.4 TCID50 of PRRSV, and a third sow was inoculated IN with virus-free cell culture medium. Serum was collected at 2- to 3-day intervals throughout the study, and tonsil biopsies were taken from each animal on day 14 post infection. The animals were euthanized and necropsied. All samples were examined histologically and tested for PRRSV by Taqman polymerase chain reaction and virus isolation.
Results: Tonsillar tissue was identified histologically in the antemortem biopsies from 21 of the breeding sows and two inoculated sows, and in all postmortem biopsies.
Implications: Tonsil biopsy is an inaccurate procedure for antemortem collection of tonsil tissue from breeding swine. Biopsies should be submitted for histopathological confirmation of tonsillar tissue. Tonsil may not be a representative target tissue for detecting PRRSV in pigs of this age, as the virus may reside in other anatomical sites.
Keywords: tonsil biopsy, PRRS eradication, persistent infection, test and removal
Cite as: Bierk MD, DEE SA, Rossow KD, et al. Experiences with tonsil biopsy as an antemortem diagnostic test for detecting porcine reproductive and respiratory syndrome virus infection in breeding swine. J Swine Health Prod 2000;8(6):279-282.
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