detection of genotype 1 porcine reproductive and respiratory syndrome virus in swine, using one-step real-time pcr for the orf7 gene

Porcine Reproductive and Respiratory Syndrome (PRRS) is the most devastating and economically challenging disease to the swine industry worldwide due to reproductive failure. The main objective of the current study was to evaluate the sensitivity and accuracy of Real-Time RT-PCR method in the detection of PRRS virus and also estimation of the pathogen load in samples with clinical signs. The primers used for the detection of PRRS virus were represented by primers with a specific sequence for the ORF7 gene of the PRRS virus. More important, the primers attachment process was influenced by punctual mutations of the viral strand belonging to the ORF7 gene. 114 samples were tested to identify the presence of PRRS virus, genotype I and 14 of them were found to be positive, using OneStep PCR. Those samples were used to test the specificity of the TaqMan probe and robustness of Real-Time RT-PCR reaction. According to the results, only the samples which presented some specific punctual mutations (4 in total, all from one particular region of Romania) at the genome level of ORF7, were positive, due to primer sequence specificity and complementarity. The Real-Time RT-PCR method has been increasingly adopted by swine producers and veterinarian laboratories as one of the most trustful techniques, combining rapidity, specificity and efficiency for detecting and monitoring the spread of PRRS virus.