Studies of the pathology of velogenic Newcastle disease: Virus infection in non‐immune and immune birds

Abstract

The pathology of velogenic viscerotropic Newcastle disease virus infection was compared in 7-and 20-week-old groups of non-immune birds and birds with two levels of immunity as determined by the haemagglutinin inhibition test. In non-immune birds the bursa at 7 and 20 weeks was the only lymphoreticular organ to show sustained reticular and lymphoid cell reactions until death took place. Caecal tonsil and spleen were extensively necrotized on day 4 after contact exposure, and similar changes occurred in lung and proventriculus. There was evidence of lymphoid recovery in birds which survived for 18 days. In immune birds the spleen showed two main responses. The first, acute reticular cell response around the ellipsoids indicated that renewed exposure to antigen was often associated with localized cell degeneration. The second, immunological, reaction was rapid formation of germinal centres which occurred somewhat earlier in 20-week-old birds (4-5 days). Especially from the second week, reticular (dendritic) cell and lymphoid hyperplasia occurred diffusely in the bursal medulla of both age groups although marked atrophy and cellular depletion, probably of physiological origin, was a feature of 20-week-old birds with high antibody levels. In the gastro-intestinal tract, germinal centre formation was most marked in the caecal tonsils at 20 weeks. With the Indonesian ITA strain of ND virus, degenerative and inflammatory changes in the brain were mild in all groups up to day 18 irrespective of immune status.

Caractérisation pathologique chez des poulets du virus vélogénique de la maladie Newcastle isolé chez une pintade

“…The greenish diarrhea and gastrointestinal lesions are in agreement with what has been described for other VVNDV strains (2,4,11,12,14,21). Contrary to the present results and those of McFerran and McCracken (15), Hamid et al (11) described gross lesions in the brain of infected chickens. Atrophy of the lymphoid organs has been described for VVNDV infections but reports of such severe thymic atrophy leading to transient disappearance of the organ have been rare (2,11,12,21).…”

“…However, Hamid et al (11) did not observe tremor of the head and torticollis contrary to results obtained in this study. The greenish diarrhea and gastrointestinal lesions are in agreement with what has been described for other VVNDV strains (2,4,11,12,14,21).…”

“…However, Hamid et al (11) did not observe tremor of the head and torticollis contrary to results obtained in this study. The greenish diarrhea and gastrointestinal lesions are in agreement with what has been described for other VVNDV strains (2,4,11,12,14,21). Contrary to the present results and those of McFerran and McCracken (15), Hamid et al (11) described gross lesions in the brain of infected chickens.…”

“…Contrary to the present results and those of McFerran and McCracken (15), Hamid et al (11) described gross lesions in the brain of infected chickens. Atrophy of the lymphoid organs has been described for VVNDV infections but reports of such severe thymic atrophy leading to transient disappearance of the organ have been rare (2,11,12,21). The atrophy and the lymphocytic depletion in the thymus, cecal tonsils and spleen were more severe than what is generally observed in IBD (18).…”

“…Hamid et al (11) studied an Indonesian strain of VVNDV and reported incubation periods of 2 to 16 days and 3 to 5 days in 7-and 20-week-old nonimmune chickens, respectively. Mortalities were 85.3 and 100%.…”