Co-Infection with Porcine Circovirus Type 2, Porcine Reproductive and Respiratory Syndrome Virus, and Porcine Parvovirus Is Common in Pig Herds

To establish a reverse transcriptase-polymerase chain reaction (RT-PCR) and a PCR method for diagnosing porcine reproductive and respiratory syndrome virus , (PRRSV) and porcine parvovirus (PPV), respectively, we designed primers based on the published sequences of the PRRSV ORF7 gene and the PPV VP2 gene. Thirty eight PCV-2-positive samples were examined by RT-PCR or PCR to investigate the mixed infection situation of PCV-2, PRRSV, and PPV in domestic pig herds. We found that 15 samples were co-infected with PRRSV and PCV-2, accounting for 39.4% of cases and 2 were with co-infected with PCV-2 and PPV, accounting for 5.3%, of cases. Moreover, 3 samples were infected with PCV-2, PRRSV, and PPV, accounting for 7.9% of cases. The results indicate that mixed infections with PCV-2, PRRSV, and PPV are common in domestic pig herds.