Comparative Efficacy of Conventional and TaqMan Polymerase Chain Reaction Assays in the Detection of Capripoxviruses from Clinical Samples

Abstract

Sheeppox and goatpox are economically important viral diseases of sheep and goats, respectively. Both diseases are reportable to the World Organization for Animal Health. To implement a control and eradication program for these diseases, a rapid and user-friendly diagnostic tool is imperative for screening. Therefore, in the present study, TaqMan quantitative polymerase chain reaction (qPCR) and conventional PCR assays targeting the DNA polymerase (DNA pol) gene were developed for the detection of Capripoxvirus DNA from clinical specimens of sheep and goats. The 2 assays used different primer sets. Conventional PCR yielded a specific product of 134 bp, whereas qPCR yielded a 180-bp product. The specificity of amplified DNA pol gene products was confirmed by their size and by sequence analysis. The 2 assays were specific for Sheeppox virus and Goatpox virus. However, in comparison to conventional PCR, the qPCR was more rapid, specific, and 100 times more sensitive, with a detection limit as low as 0.042 pg of purified DNA. The qPCR assay was more sensitive (84.05%) than conventional PCR (76.06%) when used on clinical samples (n = 71) from sheep and goats.