PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS (PRRSV) INTERACTION WITH HAEMOPHILUS-PARASUIS

The interaction of bacteria and virus has been well demonstrated in th e pathogenesis of respiratory disease in swine. The interaction betwee n porcine respiratory and reproductive syndrome virus (PRRSv) and Haem ophilus parasuis has not been studied. We initiated studies to evaluat e a possible effect of the PRRSv on the pathogenesis of polyserositis caused by H. parasuis. A group of 30 three week old piglets were distr ibuted in 4 groups. Group I (10 pigs) was inoculated with PRRSv and H. parasuis. Group II (10 pigs) was inoculated with H. parasuis alone. G roup III (5 pigs) was inoculated with virus alone and group IV (5 pigs ) was inoculated with culture media. Lesions consisted of a severe fib rinous polyserositis affecting 7 of 10 animals in group II and a mild fibrinous pleuritis in 1 of 10 animals of group I. Three of ten animal s dually infected with the two agents died during the course of the st udy. These animals had pulmonary congestion and focal lung hemorrhages . No other animals died from other groups. Group III and IV had no mac roscopic lesions. Microscopically group III had interstitial pneumonia . Immunomodulating virus effect may explain the differences in terms o f lesions severity between groups I and II. Septic shock was suspected as cause of sudden death. (C) 1997 Elsevier Science B.V.