Abstract.Lesions induced by a bovine coronavirus-like agent were studied in gnotobiotic and colostrum-fed calves using gross, histologic and electron microscopic procedures. Lesions in gnotobiotic calves were present in the colon, mesenteric lymph nodes and in all segments of the small intestine. Calves killed 4 h after the onset of diarrhea had immunofluorescent epithelial cells on the villi of the small intestine and surface of the colon. Calves killed at 44 h had shortened intestinal villi and cuboidal epithelial cells. The villusto-crypt ratio in the lower small intestine averaged 1 .O compared with 5.3 in a control calf. Immunofluorescent cells were present at the tips of the villi, and at the surface and in the crypts of the colon. Colostrum-fed calves that had serum-neutralizing antibody titers for the coronavirus-like agent developed diarrhea when inoculated orally with the agent. There was good correlation between histologic, immunofluorescent and electron microscopic iindings.Diarrhea occurred in calves 5-21 days old on several ranches during a 1971 field trial of an oral neonatal calf-diarrhea vaccine prepared from a reovirus-like agent [9]. Fecal smears from diarrheic calves were immunofluorescent negative for this agent. Diarrheic fecal material from one of the problem herds inoculated into the duodenum of a hysterotomy-derived colostrum-deprived calf caused diarrhea. Feces from this calf contained coronavirus-like particles. Subsequently diarrhea was produced in eight additional calves [9, 111 with fecal material from a calf with experimentally induced diarrhea. Pathological changes in calves inoculated with the coronavirus-like agent are described.

Gross, immunofluorescent, and light microscopic findings in seven gnotobiotic calves inoculated orally with a Reo-like neonatal calf diarrhea virus were compared to findings in three control gnotobiotic calves. Neonatal calf diarrhea virus infected primarily the villous epithelium of the small intestine. Calves examined within 1.5 h after onset of diarrhea had tall columnar immunofluorescent villous epithelial cells in the middle and lower small intestine. Calves examined 2–4.5 h after onset of diarrhea had cuboidal to squamous villous epithelial cells and an increase in reticulum-like cells in the villous lamina propria of the middle and lower small intestine. Viral tilers were 106 and 108 in colonic contents from two calves inoculated with cell-culture-adapted virus and necropsied, respectively, 2 and 6 h after onset of diarrhea.

Abstract. Neonatal calf diarrhea induced by a reovirus-like agent was studied by electron microscopy. Gnotobiotic calves were inoculated with virulent and cell-cultureadapted isolates of viruses, and similar results were obtained with both isolates. The virus infected mature villous epithelial cells of the small intestine and replicated predominantly within cisternae of the endoplasmic reticulum. Macrophages within small intestinal villi also contained viral particles. Shedding of virus into the feces apparently resulted from desquaniation of infected epithelial cells. Replacement epithelium did not contain the reovirus-like agent, was of cuboidal or squamous type, and ultrastructurally resembled immature epithelium normally found in the crypts. Escherichia coli was nonpathogenic when inoculated alone and did not adhere to the epithelium when inoculated with the virus. The reovirus-like agent was a primary pathogen since it caused diarrhea and lesions when inoculated alone or with E. coli.Diarrhea of neonatal calves has been a serious and persistent problem of the dairy industry for many years. This disease has become a major problem on ranches with cow-calf operations. Apparently an increased frequency of neonatal calf diarrhea in beef-type calves has been caused by calving during a relatively short period of time in the late winter and early spring when inclement weather causes stress. Cows and their offspring have been concentrated into small areas during the calving season, and transmission of infectious diseases to susceptible calves has been favored.A virus designated initially as neonatal calf diarrhea virus was isolated in 1968 and reported as an etiologic agent in field cases of neonatal calf diarrhea [9]. The disease was reproduced experimentally in specific pathogen-free and gnotobiotic calves inoculated with bacteria-free filtrates obtained from infected calves. Fecal material purified by ultracentrifugation and examined by

No abstract

Male and female (F-344) and male NCI-Black-Reiter (NBR) rats were dosed with 0, 35.5, or 71 mg 1,3,5-trinitrobenzene (TNB)/kg/day for 10 days. Male F-344 rats were dosed with TNB (0 and 35.5 mg/kg) for 20 and 30 days. Hematoxylin and eosin and Mallory-Heidenhain stains and alpha-2u-globulin and proliferating cell nuclear antigen immunohistochemical stains were performed on kidney sections. All treated male F-344 rats exhibited dose-related accumulation of hyaline droplets containing alpha-2u-globulin in proximal tubules. The kidney weights were significantly increased in male and female rats treated with TNB. Significant increases in cell proliferation in proximal tubules were observed in male F-344 rats. Renal changes observed in TNB-treated rats appeared identical to those from other chemicals that induce alpha-2u-globulin nephropathy in male rats. No hyaline droplet accumulation was found in female F-344 and male NBR rats at any doses. We can conclude that TNB induces dose-related exacerbation of hyaline droplets containing alpha-2u-globulin in male rat kidney and subsequent cell proliferation.