DIFFERENCE IN COUGHING AND OTHER RESPONSES TO INTRABRONCHIAL INFECTION WITH BORDETELLA-PERTUSSIS AMONG STRAINS OF RATS

Four strains of rats were each infected intrabronchially with approxim ately 10(8) CFU of Bordetella pertussis 18-323 encased in fine agarose beads, After 8 days, Sprague-Dawley rats developed the highest incide nce of coughing paroxysms, as monitored with voice-activated tape reco rders; Brown Norway, Lewis, and Hooded Lister rats coughed significant ly less frequently. Marked leukocytosis, with counts up to four times the normal levels, and retardation of normal weight gain occurred in a ll four rat strains. Both coughing and leukocytosis were greater in an imals that were infected at 4 weeks of age than in those infected at 6 weeks of age. Total serum immunoglobulin E (IgE) rose in all four rat strains 9- to 244-fold by day 8 after infection and returned to near preinfection levels at 6 weeks. Sprague-Dawley and Lewis rats, which h ad the lowest basal levels of total IgE in serum, showed the greatest degrees of elevation. All four rat strains had IgG to B. pertussis who le-cell sonicate and to filamentous hemagglutinin in 6-week-postinfect ion sera. However, the strains differed in production of IgG to pertus sis toxin, with Sprague-Dawley rats having the highest titers and Hood ed Lister and Lewis rats being nonresponders, These studies highlight the importance of rat strain as a variable in the coughing-rat model o f pertussis and validate the choice of the Sprague-Dawley rats in prev ious studies.