Experimental infections with Pasteurella septica (sero-group A) and an adeno- or enterovirus in gnotobiotic piglets

Abstract

In 2 experiments gnotobiotic Large White littermates were exposed by a daily intranasal instillation for 3 consecutive days to either adenovirus type 4 or enterovirus type 2, Past. septica PL 100 (sero-group A), or this bacterium plus one or other of these viruses. The piglets in the experiments were 8 and 10 days old respectively at the time of first exposure to these various infections. Each type of pure virus infection produced a macroscopically visible pneumonia, the extent of which was not markedly enhanced by the additional presence of the bacterium, although the histological pattern of the lesions differed somewhat in the latter instance. In the case of the enterovirus-pasteurella combination the pneumonia included the development of a relatively pronounced peribronchiolar aggregation of lympho-reticular elements. Although the combined viral-bacterial inocula did not greatly enhance the distribution of the pneumonic lesions, severe lesions, resembling those of Glässer's disease, arose in piglets given these combined infections. The main abnormality was a sero-fibrinous serositis especially in the thorax. Past. septica alone elicited only doubtful inflammatory lesions of the lungs, except in 1 animal in which lethal fibrinous pneumonia and septicaemic changes occurred.