VIRAL PROVENTRICULITIS IN CHICKENS

The objectives of the present study were to examine proventriculi of b roiler chicks for lesions, and to classify and record the incidence of these lesions. Deep non-purulent necrotizing proventriculitis (accomp anied by adenoepithelial hypertrophy and hyperplasia) was the most com mon (109/220 = 49.5%) light microscopic diagnosis in the proventriculi examined. Degenerating and necrotic alveolar secretory cells had amor phous, granular or vacuolated cytoplasm. Nuclei usually were either py knotic, karyorrhectic or karyolytic; however, fewer attached or slough ed cells had swollen nuclei with marginated chromatin and clear centre s. Basophilic inclusion bodies were never seen. In five cases examined ultrastructurally, hexagonal virus particles were found in intact nuc lei (average size = 68.9 nm, n = 89), associated with unbound condense d chromatin, and within vacuolated spaces in the cytoplasm (average si ze = 62.3 nm, n = 109). DNA in situ hybridization failed to detect ade novirus or polyomavirus nucleic acids. The presence of intralesional v irus suggests that a causal relationship might exist between the virus and the proventricular lesions.