Porcine Circovirus Type 2 Infection Decreases the Efficacy of a Modified Live Porcine Reproductive and Respiratory Syndrome Virus Vaccine

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV)-induced pneumonia is a major problem, and vaccination is used to reduce losses associated with PRRSV. Porcine circovirus type 2 (PCV2) causes lymphoid depletion, and there is concern that this adversely affects the immune response. The objective of this study was to investigate the effect of PCV2 infection on the efficacy of modified live virus (MLV) PRRSV vaccine. Sixty-nine 2-week-old pigs were randomly assigned to one of seven groups of 9 to 10 pigs each. At 6 weeks of age, pigs in groups 4, 5, and 6 were inoculated intranasally with PCV2 ISU-40895. At 8 weeks of age, groups 3, 4, 6, and 7 were vaccinated with a PRRSV MLV vaccine. At 12 weeks of age, groups 2, 3, and 4 were challenged with PRRSV SDSU73. All pigs were necropsied 14 days after PRRSV challenge. PCV2-infected, PRRSV-vaccinated, and PRRSV-challenged pigs had significantly (P < 0.05) more-severe macroscopic lung lesions than did the PRRSV-vaccinated and PRRSV-challenged pigs that were not exposed to PCV2 prior to PRRSV vaccination. Nonvaccinated PRRSV-infected pigs had a significantly (P < 0.001) higher incidence of PRRSV antigen in lungs than did all other groups except the group infected with PCV2 prior to PRRSV vaccination and challenge. The nonvaccinated PRRSV-challenged group and the group challenged with PCV2 prior to PRRSV vaccination and challenge had significantly (P < 0.001) lower average daily weight gain than did the control and the vaccinated groups. This work suggests that PCV2 infection has an adverse effect on the development of protective immunity induced by PRRSV vaccine.

Assessment of recombinant beak and feather disease virus capsid protein as a vaccine for psittacine beak and feather disease

“…That this occurred despite vaccinated birds having detectable anti-BFDV antibodies before being challenged indicates that vaccination does not prevent viral replication. This is a common scenario with other vaccines (Opriessnig et al, 2006) and is not surprising in this case. This evidence of viral replication may not have been detected if a standard PCR assay alone had been used.…”

Porcine Circovirus Type 2–Associated Disease: Update on Current Terminology, Clinical Manifestations, Pathogenesis, Diagnosis, and Intervention Strategies

“…99 Singular experimental infection using the same PCV2 isolate at a similar cell culture passage and dose had failed to induce clinical PCVAD in crossbred SPF pigs. [32][33][34][35][36]49,100,101,104,106,107 Another research group experimentally induced systemic PCVAD in colostrum-deprived Landrace/Large White crossbred pigs inoculated with a PCV2 isolate recovered from a subclinically infected Yorkshire pig, implying host-and/or environment-dependant factors associated with the development of PMWS. 2 A correlation between the type of adaptive immune response against PCV2 and the level of virus replication provided evidence of host variations in the onset of the adaptive immune response, which may account for the differences in PCV2 replication and clinical manifestation and outcomes of PCV2-associated disease among pigs.…”

Frequent Detection of Highly Diverse Variants of Cardiovirus , Cosavirus , Bocavirus , and Circovirus in Sewage Samples Collected in the United States

“…Circoviruses have been reported in birds and mammals and are associated with potentially fatal diseases causing lymphoid tissue damage and immunosuppression in infected animals (48,56,57). Circovirus pathogenicity in pigs has been studied extensively, since frequent infections have a significant economic impact (11,26,45,51). Porcine circovirus infections have been reported worldwide, including many countries in Europe and Asia and in Canada, United Kingdom, New Zealand, and the United States (2).…”