INTERACTIONS AMONG PORCINE REPRODUCTIVE AND RESPIRATORY SYSTEM VIRUS (PRRSV), BORDETELLA BRONCHISEPTICA AND HAEMOPHILUS PARASUIS IN SWINE RESPIRATORY DISEASE

摘要

Porcine respiratory disease complex (PRDC) is a multifactorial pneumonia caused by infection with multiple pathogens. The potential contribution of PRRSV and B. branchiseptica to PRDC was discovered after initial studies were conducted examining the effects of PRRSV on challenge with either Pasteurella multocida or B. bronchiseptica (1,2). Infection with PRRSV predisposed pigs to pneumonia with B. bronchiseptica but not P. multocida. Prior infection with B. bronchiseptica enabled P. multocida to colonize the upper respiratory tract but did not affect the ability of these agents to gain access to the lower respiratory tract. This led to the theory that the combination of PRRSV and B. bronchiseptica may leave pigs more susceptible to pulmonary infection with opportunistic bacteria such as P. multocida. Challenge with P. multocida following coinfection with PRRSV and B. bronchiseptica resulted in recovery of P. multocida from the lung. We are now examining whether B. bronchiseptica and/or PRRSV predisposes to colonization and disease with H. parasuis.