Porcine parvovirus-7 (PPV7) has frequent co-infections with porcine
circovirus 3 (PCV3) in sows with reproductive failure and may promote
PCV3 viremia
Abstract
Porcine parvoviruses (PPVs) and porcine circoviruses (PCVs) infect pigs
worldwide, with PPV1-7 and PCV2 infections common in pigs. Although PPV7
was only identified in 2016, co-infection of PPV7 and PCV2 is already
common and PPV7 may stimulate PCV2 replication. PCV3, a novel type of
circovirus, is prevalent worldwide and believed to cause reproductive
disorders and dermatitis nephrotic syndrome. In recent studies, pigs
were commonly infected with both PCV3 and PPV7. Our objective was to
investigate co-infections between PPV7 and PCV3 in samples from swine on
farms in Hunan, China, and assess potential impacts of PPV7 on PCV3
viremia. A total of 399 porcine serum samples, negative or positive for
PCV3, were subjected to real-time PCR to detect PPV7; of these samples,
190 were from farms with long-standing histories of reproductive failure
(RF) and were selected to determine whether PPV7 affected PCV3 viremia.
Among 209 serum samples, 23% (48/209) were positive for PPV7 and the
PPV7-positive rate was significantly higher in PCV3 positive serum
(31.4%) than negative serum (14.4%). Among 190 serum samples, 45.1%
(28/62) were positive for PPV7 and PCV3 and the PPV7-positive rate was
significantly higher in PCV3 positive RF-serum (51.2%) than in non-PCV3
RF-serum (34.8%); furthermore, there was a higher PPV7 prevalence
(55%) in PCV3-positive aborted fetus samples. In addition, the Ct value
of PCV3 in PPV7 positive samples was significantly lower than that in
PPV7 negative serum samples. Based on our findings, we concluded that
PPV7 may stimulate PCV3 replication.