Gnotobiotic Calves Research Articles

Modification of a Technique for Deriving Gnotobiotic Calves

Modifications have been made to improve the sterility and viability of calves derived by a hysterotomy and slaughter technique. These include the use of a different adhesive and the construction of a pivoting crush-operating table to facilitate manoeuvring and restraining the dam.

Isolation of coronaviruses from neonatal calf diarrhoea in Great Britain and Denmark

Coronaviruses were isolated from neonatal calves with diarrhoea in Great Britain and Denmark. They were serially passed in gnotobiotic calves which developed acute diarrhoea. Pathological lesions were found in the small and large intestines. Coronaviruses were demonstrated by electron microscopic examination of the faeces and intestinal contents, immunofluorescent staining of sections of small and large intestine and by isolation in tracheal organ cultures. In early passages of the British coronavirus, particles of about 30 nm in diameter were observed in the faeces by electron microscopy. These particles were removed from the coronavirus preparations by cross-protection experiments in calves. The coronaviruses were morphologically and antigenically similar to the bovine coronavirus isolated in the United States and the British virus was adapted to replicate in calf kidney cell cultures.

Studies on cross protection induced in calves by rotaviruses of calves, children and foals

Inoculation at birth with a live attenuated strain of a bovine rotavirus isolated in the USA (scourvax-reo) induced protection in five gnotobiotic calves seven to 21 days later against a UK isolate of pathogenic bovine rotavirus. However, no protection was induced in three calves challenged three to five days after vaccination. There was a close antigenic relationship demonstrated between the two bovine rotavirus isolates. In contrast only one of three gnotobiotic calves inoculated with foal rotavirus, and one of three with human rotavirus, were protected against bovine rotavirus challenge. Protection in these two calves correlated with high heterologous immunofluorescent antibody titre (320 or greater), although the neutralising antibody titres was less than 20.

Intestinal lesions induced in gnotobiotic calves by the virus of human infantile gastroenteritis.

Four gnotobiotic calves with intestinal lesions induced by third and fourth calf passages of virus of human infantile gastroenteritis were studied by light microscopy, scanning and transmission electron microscopy, and by immunofluorescence. Calves, 25--72 hours old, were examined 0.5 hours, 3 hours, 7 hours, and 48 hours after the onset of diarrhea. Intestinal histology of infected calves was compared to that of two noninoculated gnotobiotic calves 48 and 72 hours old. The sequence of events in the small intestine was infection of the absorptive villous epithelial cells, replacement of the tall columnar villous epithelial cells with cuboidal and squamous cells, shortening of the villi, enlargement of reticular cells, lymphocytic infiltration of the villous lamina propria and repair.

A Simplified Apparatus for the Microbiological Isolation of Calves

SUMMARY An isolator has been developed for rearing gnotobiotic and specific pathogen free (SPF) calves. The isolator consisted of relatively cheap components which could be rapidly assembled; the upper half being a flexible polyvinyl chloride (PVC) canopy clamped to a glass fibre tank. This formed the lower half of the microbiological barrier, and also served as the calf pen. The assembled isolator could be sterilized with peracetic acid. Over fifty gnotobiotic calves have been reared successfully in this type of isolator. Some calves were kept for up to five months, though the average time within the isolator was one month. Ten cases of contamination were thought to be attributable to faults in the rearing isolator. No cases of cross contamination of experimental agents from one isolator to another were discovered in either gnotobiotic or SPF animals.

Induction of pneumonia in gnotobiotic calves following inoculation of Mycoplasma dispar and ureaplasmas (T-mycoplasmas)

Cloned cultures of Mycoplasma dispar and of Ureaplasma sp were inoculated endobronchially into gnotobiotic calves. The resulting pneumonia was estimated to involve 2 to 10 per cent of the lung although no clinical signs were observed. The histopathological lesions consisted of infiltration with mononuclear cells, cuffing (peribronchiolar lympho-reticular hyperplasia), catarrhal bronchiolitis and atelectasis. The results indicate that both M dispar and Ureaplasma sp are capable of causing sub-clinical cuffing pneumonia in calves.

Diarrhea in gnotobiotic calves caused by the reovirus-like agent of human infantile gastroenteritis

Gnotobiotic newborn calves were found to be susceptible to infection with the reovirus-like agent of human infantile gastroenteritis (HRVL). Infection was based on (i) seroresponse using immunofluorescence and (ii) fecal shedding of virus particles using electron microscopy. Virus was detected in fecal samples for at least 2 to as long as 7 days after inoculation, although peak virus concentrations were observed on days 1 to 4. Diarrheal illness was observed in seven calves on second to fourth serial passage of HRVL in calves but in none of four animals studied on first passage. Diarrhea began 15 to 30.5 h (mean = 22.3 h) post-inoculation and lasted less than 24 h; three of the seven animals that developed diarrhea were also depressed or anorectic.

The Derivation of Gnotobiotic Calves by a Hysterotomy and Slaughter Technique

SUMMARY The object of this work was to devise an economically acceptable system of producing large numbers of gnotobiotic calves. During the past two years, 37 hysterotomies have been performed, yielding 35 viable calves which required little or no resuscitation. The operation itself took a maximum of 10 minutes, required two simple PVC isolators, which could be easily assembled and sterilized, and yielded a carcass suitable for salvage. All the carcasses were passed as fit for human consumption.

Pneumonia and arthritis in gnotobiotic calves following inoculation with Mycoplasma agalactiae subsp bovis.

Pneumonia and arthritis in gnotobiotic calves following inoculation with Mycoplasma agalactiae subsp bovis.

Experimental infection of calves with respiratory syncytial virus

Three bovine isolates and one human isolate of RS virus were given intranasally to gnotobiotic, colostrum-deprived and conventional calves. All isolates produced a biphasic pyrexia associated with a serous nasal discharge. Virus was recovered from nasal secretions 4-10 days after inoculation from nasal, tracheal and bronchial mucosae and lung of animals killed 7-13 days after inoculation. Infection did not produce any macroscopic lesions, but histologically there was a focal degenerative rhinitis and a catarrhal bronchiolitis with the occasional formation of syncytia in bronchioles and alveoli.

The Isolation of a Reovirus-like Agent Associated with Diarrhoea in Colostrum-deprived Calves in Great Britain

The isolation of a virus from calves with diarrhoea is described. On the basis of morphology, serology and pathogenesis the virus is similar to the reovirus-like agent isolated in the United States of America. The virus was serially passaged in colostrum-deprived and gnoto-biotic calves, all of which developed diarrhoea, with re-isolation of the agent from challenged calves.

Pathology of neonatal calf diarrhea induced by a coronavirus-like agent.

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 villus-to-crypt ratio in the lower small intestine averaged 1.0 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 findings.

Meningo-encephalitis in Two Gnotobiotic Calves Infected Intranasally and Orally with Infectious Bovine Rhinotrachcitis Virus

Summary Two gnotobiotic calves were inoculated intranasally and orally with IBRV. One calf developed a fever, conjunctivitis and a nasal discharge while the other remained clinically normal throughout the experiment. Four weeks after inoculation both calves had a microscopic meningo-encephalitis, the lesions occurring in the pons, gyrus sygmoideus posterior, and the corpus striatum.

Pathology of Neonatal Calf Diarrhea Induced by a Reo-Like Virus

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.

The production of gnotobiotic piglets and calves by hysterotomy under general anaesthesia.

The production of gnotobiotic piglets and calves by hysterotomy under general anaesthesia.

Studies on a rhinovirus (EC11) devived from a calf: II. Disease in calves

Three gnotobiotic calves were killed 4, 6 and 26 days after intranasal inoculation with the rhinovirus EC11. The clinical signs and lesions produced were closely similar with those observed in the calf from which the virus was originally recovered and which was killed 3 days after the onset of clinical signs. In all calves there was a diphasic temperature reaction with the first peak 36 to 48 hr. after inoculation, an increase in respiration rate and a serous nasal discharge. The only macroscopic lesions were in the lungs in which a few small, dark red areas of collapse were observed. Histologically, lesions were not marked and they were minimal in the calf killed 26 days after infection. In the turbinates and tracheas there were a few foci of epithelial necrosis, enhanced mucous activity and migration of leucocytes into the epithelial and subepithelial tissues. In the lungs there were areas of microatelectasis and interstitial pneumonia. The virus was isolated in organ culture from the lungs, tonsils, and turbinates of the original calf, from the trachea and turbinates of the calf killed 6 days after inoculation and from the turbinates and tonsil of that killed 4 days after inoculation. No attempts were made to reisolate virus from the calf killed 26 days after infection. Serum from that calf neutralised EC11 virus but not Sd-1 virus of Bögel and Böhm.