EXPERIMENTAL PNEUMONIA OF PIGS INFECTED WITH AUJESZKYS-DISEASE VIRUS AND ACTINOBACILLUS-PLEUROPNEUMONIAE

Experimental infections were induced out to examine whether Aujeszky's disease virus (ADV) infection in pigs results in a severe pneumonia b y Actinobacillus pleuropneumoniae. Intranasal inoculation of ADV (10(6 .9) median tissue culture infective dose/head) in 4-month-old primary specific-pathogen-free pigs was followed by the inoculation of A. pleu ropneumoniae type 1 (10(3.1) or 10(5.1) colony-forming-units/head). Th e pigs inoculated with ADV alone developed clinical signs of Aujeszky' s disease but not pneumonia, and those inoculated with A. pleuropneumo niae (10(3.1) CFU/head) alone did not develop clinical symptoms and lu ng lesions. Whereas all the pigs inoculated dually with ADV and A. ple uropneumoniae (10(3.1) CFU/head) showed severe or very severe clinical symptoms and moderate or severe pneumonia and one of them died. The p igs inoculated with A. pleuropneumoniae (10(5.1) CFU/head) alone had s evere clinical symptoms and one of the 2 pigs died acutely. Furthermor e, all of the 3 pigs inoculated with ADV and A. pleuropneumoniae (10(5 .1) CFU/head) showed clinical symptoms and moderate or severe pneumoni c lesions and one pig died of disease. It was concluded that the clini cal symptoms of A. pleuropneumoniae became severer by concomitant infe ction with ADV.