Development of SYBR Green I-based quantitative PCR assay for identification of porcine circovirus 1, 2 and 3

Porcine Circovirus (PCV) includes Porcine Circovirus 1(PCV1), Porcine Circovirus 2 (PCV2) and Porcine Circovirus 3 (PCV3). In recent years, co-infection exists between PCV1, PCV2 and PCV3 serotypes. Therefore, it is particularly necessary to establish a fast, specific and sensitive SYBR Green I real-time quantitative PCR detection method for PCV1, PCV2 and PCV3. In this experiment, specific primers were selected and the reaction conditions were optimized. A real-time quantitative PCR identification method was established. The results showed the detection limits of this assay were 40.3 copies/μl for PCV1, 25.2 copies/μl for PCV2 and22.4 copies/ μl for PCV3. There was no cross-reactivity with swine fever virus (CSFV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine pseudorabies virus (PRV) and porcine parvovirus (PPV). The intra-assay and inter-assay coefficients of variation were less than 1%. The test results of 100 PCV suspected positive samples revealed that the PCV1, PCV2 and PCV3 singular infection rate was 10% (10/100), 64% (64/100) and 52% (52/100), respectively. The PCV1 and PCV2 co-infection rate was 8% (8/100), the PCV1 and PCV3 co-infection rate was 7% (7/100), the PCV2 and PCV3 co-infection rate was 26% (26/100), and the PCV1, PCV2 and PCV3 co-infection rate was 7% (7/100). This method has good specificity, sensitivity and stability. It provides a promising tool for rapid differential detection of PCV1, PCV2 and PCV3.