Use of a portable real-time reverse transcriptase-polymerase chain reaction assay for rapid detection of foot-and-mouth disease virus

Abstract

Objective: To evaluate a portable real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assay designed to detect all 7 viral serotypes of foot-and-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.