Porcine Reproductive and Respiratory Syndrome Virus Infection at the Time of Porcine Circovirus Type 2 Vaccination Has No Impact on Vaccine Efficacy

Abstract

Several porcine circovirus type 2 (PCV2) vaccines are now commercially available and have been shown to be effective at decreasing the occurrence of porcine circovirus-associated disease (PCVAD). Many herds are coinfected with PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV). Some producers and veterinarians are concerned that if pigs are vaccinated for PCV2 at or near the time that they are typically infected with PRRSV, the efficacy of the PCV2 vaccine will be compromised. The impact of PRRSV on PCV2 vaccination is unclear and has not been investigated under controlled conditions. The objective of the present study was to determine whether the presence of PRRSV viremia has an effect on the efficacy of commercial PCV2 vaccinations. Three-week-old PCV2-negative conventional pigs with passively derived anti-PCV2 antibodies were either vaccinated with one of three commercial PCV2 vaccines or left nonvaccinated. A portion of the pigs were infected with PRRSV 1 week prior to PCV2 vaccination. To determine vaccine efficacy, a PCV2 challenge was conducted at 8 weeks of age. PCV2 vaccination, regardless of PRRSV infection status at the time of vaccination, was similarly effective in inducing an anti-PCV2 IgG response in the presence of maternally derived immunity and in protecting the pigs from PCV2 challenge, as determined by a reduction in the level of PCV2 viremia and a reduction in the prevalence and amount of PCV2 antigen in lymphoid tissues in vaccinated pigs compared to nonvaccinated pigs. The results indicate that acute PRRSV infection at the time of PCV2 vaccination has no adverse effect on PCV2 vaccine efficacy.

Comparative Effects of Vaccination against Porcine Circovirus Type 2 (PCV2) and Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in a PCV2-PRRSV Challenge Model

“…These results suggest that the reduction of PRRSV viremia by the PRRSV vaccine is affected by the pig's PCV2 infection status. Our results agree with those of previous similar studies, in which PRRSV infection at the time of PCV2 vaccination had no impact on the efficacy of the vaccine but PCV2 infection at the time of PRRSV vaccination did affect the efficacy (38,39). Our results are clinically meaningful, indicating that swine practitioners should check PCV2 infection statuses in pigs before PRRSV vaccines are used to control PRRSV infection in swine herds.…”

Recognition of the Different Structural Forms of the Capsid Protein Determines the Outcome following Infection with Porcine Circovirus Type 2

“…In this study, the infection of pigs with a combination PCV2 and PRRSV did not result in mortality or the appearance of fullblown PCVAD, which was observed previously (1,30,36,40,43). It is difficult to faithfully reproduce PCVAD, even in the presence of known infectious disease cofactors.…”

“…One example is the experimental coinfection of pigs with PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV). Coinfection results in increased PCV2 viremia and the appearance of clinical signs resembling PCVAD (1,30,36,40,43).…”

Concurrent infections are important for expression of porcine circovirus associated disease

“…To better mimic what is going on under field conditions and to have an improved model to test the efficacy of different treatment strategies for PCV2, polymicrobial experimental inoculations have gained importance in recent years. It is not uncommon to inoculate pigs concurrently with PCV2 and PRRSV (Opriessnig et al, 2008;Sinha et al, 2010), PCV2, PRRSV and SIV (Opriessnig et al, 2009), or PCV2, PRRSV andPPV (Opriessnig et al, 2011c;Shen et al, 2010). The PCV2 and M. hyopneumoniae co-infection model was recently used to investigate the effect of PCV2 vaccination on boars with emphasis on clinical disease and PCV2 shedding in semen (Opriessnig et al, 2011b).…”