Real-time PCR to detect and analyze virulent PPV loads in artificially challenged sows and their fetuses

To establish a real-time polymerase chain reaction with SYBR^® Green for detection and quantification of porcine parvovirus (PPV) in porcine tissues, two primers specific for the non-structural protein 1 gene were designed. The detection limit of this assay was 3–23 gene copies/reaction, equivalent to 0.001 TCID₅₀/ml. The assay was linear over a 10⁶ dilution range of template concentrations. Other porcine pathogens involved in reproductive disorders (porcine circovirus 2, porcine reproductive and respiratory virus, pseudorabies virus, classical swine fever virus) were negative by this assay. This assay could detect PPV titres at least 10⁵ smaller than the hemagglutination assay. To better understand the pathogenesis of PPV, the levels of viral DNA in various tissues of artificially challenged sows and their fetuses were quantified with this method. The virus was found mainly in the heart, lung, spleen, kidney, and endometrium of sows, and mainly in the heart, spleen, lung, and testis of fetuses. This study provides a new tool for the study of PPV infection and distribution in sows and their fetuses.