Field efficacy of a novel porcine reproductive and respiratory syndrome modified‐live virus vaccine with an emphasis on growth performance

Abstract

Abstract Background This field evaluation was designed to evaluate the efficacy of a new porcine reproductive and respiratory syndrome virus‐2 (PRRSV‐2) modified live virus vaccine at three independent pig farms. Methods Three farms were selected for this study based on their respiratory disease status caused by PRRSV‐2 infection in post‐weaning and growing pigs. Each farm housed a total of 40, 18‐day‐old pigs that were randomly allocated to one of two treatment groups. Pigs were administered a 1.0 mL dose of the bivalent vaccine intramuscularly at 21 days of age in accordance with the manufacturer's recommendations, whereas unvaccinated pigs were administered a single dose of phosphate buffered saline at the same age. Results Vaccinated groups were measured and calculated significantly (p < 0.05) higher in body weight and average daily weight gain on all three farms compared with unvaccinated groups. Vaccinated groups elicited PRRS antibodies and PRRSV‐2‐specific interferon‐γ secreting cells, which reduced the amount of PRRSV‐2 genomic copies in the blood and reduced macroscopic and microscopic lung lesions severity when compared with unvaccinated groups. Conclusions The field evaluation data demonstrated that a new PRRSV‐2 modified live virus vaccine was efficacious in swine herds suffering from respiratory diseases caused by PRRSV‐2 infection.

Keywords

• modified‐live virus vaccine
• porcine reproductive and respiratory syndrome virus
• respiratory disease