Experimental researches in infections with associated myxoviruses in the mouse.

Abstract

Infections with influenza virus, A/Beijing 353/89 (H3N2) strain, to which there were associated parainfluenza virus type 3, 739-2D strain, adenovirus type 3, and respiratory syncytial virus Long strain, were experimentally induced in white mice. The experimental models were set up so as to permit the obtaining of an associated infection with three viruses, in which the influenza virus should be inoculated the first, the participation of the others being variable, according to their presence by alternation. The infections were detected by means of the presence of homologous serum antibodies, of positive immunofluorescence reactions in the pulmonary tissue, of the histological, histochemical and histoenzymatic lesions at the level of the respiratory system, as well as of pathomorphological changes in other organs. The severity of lesions varied from one to another infection produced by a viral association. At the level of the pulmonary parenchyma, the inflammatory lesion had a frequency of 100%. The severest pathomorphological picture characterized the diffuse interstitial lymphohistio-macrophagocytic bronchopneumonia. The bronchopulmonary block was marked by cytoinfiltrative processes, with a prevalence of lymphocytes in the infection with influenza virus + adenovirus + respiratory syncytial virus, but with a proportionality between lymphocytes and histiocytes in the other infections. The lesion of the highest incidence was the thickening of interalveolar septa, as a consequence of stasis hyperemia, oedema and lymphohistio-macrophagocytic cytoinfiltrate, sometimes associated with hyalinosis of tunica media of the blood vessels and of the Reisseisen's muscle. In other organs, particularly in the liver and kidney, vascular lesions, stasis hyperemia, inflammatory and dystrophico-inflammatory lesions were present; in the spleen, megakaryocyte hyperplasia was recorded at a significant rate in associated infections in which the adenovirus was present.