CONCURRENT VACCINATIONS TO PRRSV AND PCV2 INDUCES CLINICAL PROTECTION IN NATURALLY INFECTED PIGS

Objective - This field trial was aimed at assessing the efficacy of the concurrent use of PCV2 + PRRS vaccinations in comparison with the effects of both single vaccinations (PRRS and PCV2 alone) and with negative non-vaccinated control pigs, by measuring viremia, morbidity and mortality. Materials and Methods - This double-blinded trial was carried out in a farrow to finish 2000-sow-herd affected by PCVD and infected by PRRSV in nursery and growing phase (stable herds). PCV2 and PRRS vaccinations have been never applied prior to this trial. At weaning (22.5±1.3 days of age) 800 piglets individually identified were equally distributed to 4 different groups as follow: A (concurrent vaccination with Porcilis PRRS - right side of the neck, + Porcilis PCV - left side); B (Porcilis PRRS only); C ( Porcilis PCV only); D (Placebo -adjuvant/control). Blood samples (20 pigs/group) were taken every 2 weeks for the whole duration of the trial in order to perform virological exams for PCV2 and PRRS by Q-PCR. On a weekly basis clinical signs (morbidity) were recorded by using a standardized scoring system (Segalés et al, 2009). Mortality was recorded also. Statistical analysis was performed by a GAMM (morbidity), GLMM (viremia) and Cox proportional Hazard Model (survival). Results - PRRS natural infection occurred from 8 to 18 weeks of age and PCV2 infection from 16 weeks of age onward. In these two periods the course of clinical score in control pigs (group D) and in non-vaccinated animals (group C – Porcilis PCV only and B – Porcilis PRRS only) was characterized by a statistically significant increase. Moreover, in PCV2 vaccinated animals (groups A and C) the viral burden in blood was significantly reduced (p< 0.01) as compared to PCV2-non vaccinated pigs (Groups B and D). Overall, morbidity in concurrently vaccinated pigs (group A) was significantly lower (p<0.01) than the other groups. Survival rate in all vaccinated groups (A, B and C) was statistically higher than group D. Conclusions. In the condition of this study, the results show that concurrent vaccinations to PRRS and PCV2 is safe and improves the health status of the treated pigs when naturally exposed to both infections.