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  • Author or Editor: Fernando A. Osorio x
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Abstract

Objective

To compare the sensitivities of all available serologic tests in detecting pseudorabies virus (PRV) antibodies in pigs during long-term latent pseudorabies.

Design

Pigs experimentally infected with a virulent strain of PRV were maintained for 2 to 27 months after inoculation. At the time of necropsy of each pig, blood was collected for serologic evaluation, and tissues were obtained for polymerase chain reaction (PCR) verification of latency.

Animals

65 crossbred pigs each weighing approximately 18 kg at the start of the study.

Procedure

Serum samples from each pig were analyzed by serum neutralization, latex agglutination, screening ELISA, particle concentration fluorescence immunoassay, automated latex agglutination, and differential ELISA for glycoproteins I, III, and X. DNA was extracted from the trigeminal ganglia and tonsils of each pig and was analyzed by PCR for PRV genomic sequences.

Results

PCR analysis of trigeminal ganglia and tonsils indicated that all pigs were latently infected with PRV at the time of necropsy, and serologic testing verified that all pigs had PRV-specific antibodies, regardless of duration of infection. The screening tests were virtually equivalent in sensitivity for detection of PRV antibodies. Of the differential serologic tests, the glycoprotein-l and -III marker systems, which performed with similar sensitivity as the screening tests, were superior to the glycoprotein- X marker system in detecting PRV antibodies in latently infected pigs

Conclusion

Serologic testing consistently detects pigs in the latent phase of PRV infection, provided that the test detects the antibody response to the whole virus or to a reliable PRV-marker glycoprotein. (Am J Vet Res 1996; 57:608–611)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate a portable real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assay designed to detect all 7 viral serotypes of footand- mouth disease virus (FMDV).

Design—Laboratory and animal studies.

Study Population—Viruses grown in tissue culture and animals experimentally infected with FMDV.

Procedure—1 steer, pig, and sheep were infected with serotype O FMDV. Twenty-four hours later, animals were placed in separate rooms that contained 4 FMDV-free, healthy animals of the same species. Oral and nasal swab specimens, oropharyngeal specimens obtained with a probang, and blood samples were obtained at frequent intervals, and animals were observed for fever and clinical signs of foot-and-mouth disease (FMD). Samples from animals and tissue cultures were assayed for infectious virus and viral RNA.

Results—The assay detected viral RNA representing all 7 FMDV serotypes grown in tissue culture but did not amplify a panel of selected viruses that included those that cause vesicular diseases similar to FMD; thus, the assay had a specificity of 100%, depending on the panel selected. The assay also met or exceeded sensitivity of viral culture on samples from experimentally infected animals. In many instances, the assay detected viral RNA in the mouth and nose 24 to 96 hours before the onset of clinical disease.

Conclusions and Clinical Relevance—The assay reagents are produced in a vitrified form, which permits storage and transportation at ambient temperatures. The test can be performed in 2 hours or less on a portable instrument, thus providing a rapid, portable, sensitive, and specific method for detection of FMDV. (J Am Vet Med Assoc 2002;220:1636–1642)

Full access
in Journal of the American Veterinary Medical Association