Vaccination of influenza a virus decreases transmission rates in pigs

Romagosa, Anna; Allerson, Matt; Gramer, Marie; Joo, Han Soo; Deen, John; Detmer, Susan; Torremorell, Montserrat

Thirteen days after the second vaccination, nasal swabs and blood samples were taken from all pigs, and the seeder pigs were moved to a separate room for challenge. At 48 h post challenge, the seeder pigs were placed back to each room in contact with their original pen mates (1 seeder pig/group/replicate) until the termination of the study. To determine transmission, all pigs were sampled daily by taking nasal swabs and observed daily for presence of clinical signs consistent with influenza. The transmission experiment ended at 14 days post contact (dpc) or when all 10 contact pigs in a room became influenza virus positive. At that point, pigs were humanely euthanized with an intravenous lethal dose of pentobarbital at the prescribed amount of 100 mg/kg (Fatal-Plus Solution ® , 250 mL, Vortech Pharmaceuticals, Dearborn, MI, USA).