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D R Snodgrass

Publications and source records attributed to D R Snodgrass.

At least 55 records · Page 3Linked to original sources
PubMed1984

Evidence for serotypic variation among bovine rotaviruses.

Eight field strains of calf rotavirus from the U.K. were compared by neutralisation tests, using convalescent and hyperimmune antisera. Seven of these strains cross-reacted and were considered to be of one serotype, while the 8th was distinguished by a greater than 20-fold two-way difference in neutralisation titre suggesting a second serotype. Three widely-distributed reference strains (U.K., Northern Ireland and Lincoln) cross-reacted with the strains in the dominant serotype, as did 33 of 42 other field calf rotavirus strains. Nine field strains failed to cross-react with either serotype, suggesting the existence of other potential serotypes in the calf population.

Animals↗
PubMed1984

Experimental cryptosporidiosis in germfree lambs.

Contaminating bacteria were removed from an isolate of calf Cryptosporidium by 3 sequential passages of the parasite in gnotobiotic lambs, together with antibiotic treatment of the lambs. This preparation, which contained no detectable bacteria or viruses, was given by mouth to 8 2-day-old gnotobiotic lambs, 3 of which were dosed at the same time with bacterial flora from a healthy calf. Lambs were killed at intervals from 12 to 288 h post-inoculation and the sequential development of the parasite, of enteric lesions, and of clinical illness was observed. Lesions were characterized by severe villus stunting and fusion. Clinically the most consistent sign was anorexia, with some lambs developing also a severe watery diarrhoea. Lesions and clinical signs were similar in lambs with and without intestinal bacteria. This demonstration of the enteropathogenicity of Cryptosporidium in germfree lambs suggests that it is a pathogen of significance.

Animals↗
PubMed1984

Comparison of atypical rotaviruses from calves, piglets, lambs and man.

Some rotaviruses from calves, piglets, and lambs were detected by electron microscopic examination of faeces but not by an enzyme-linked immunosorbent assay which relies on detection of group antigen. On further examination by polyacrylamide gel electrophoresis, these viruses had 11 segments of dsRNA, as had typical rotaviruses, but arranged in atypical patterns. From humans, three rotaviruses with atypical electrophoretypes were also detected. Gnotobiotic animals were infected with atypical calf, piglet and lamb rotaviruses, and used to provide antigen and antiserum for an immunofluorescent comparison of these rotaviruses with conventional rotaviruses and other previously described atypical rotaviruses from piglets and chickens. Two atypical rotaviruses from humans failed to infect gnotobiotic piglets. The atypical rotaviruses could be tentatively categorized into two groups serologically distinct from each other and from conventional rotaviruses, and these distinctions were consistent with electrophoretypes . The atypical chicken rotavirus may form a fourth distinct group. These findings are consistent with the hypothesis that rotaviruses belong to at least four separate groups definable by serology and electrophoretype .

Animals↗
PubMed1984

Bovine rotavirus serotypes and their significance for immunization.

Neutralization assays on calf fecal rotavirus with antisera to two previously described bovine rotavirus serotypes allowed the isolation of four rotaviruses belonging to a distinct third serotype. In a survey of 85 calf isolates, 80 rotaviruses belonged to serotype 1 (91%), 1 belonged to serotype 2 (1%), and 4 belonged to serotype 3 (5%). Serotypes 1 and 2 were shown to not cross-protect in a passive immunization experiment in gnotobiotic lambs. Ingestion of specific antiserum protected against infection with the homologous, but not heterologous, serotype. Rabbits with no previous exposure to rotavirus responded to sequential vaccination with bovine and human rotavirus serotypes with antibody specific to those serotypes, and the response did not broaden to include serotypes to which they had not been exposed. These factors suggested the need for multivalent rotavirus vaccines. By contrast, 47 adult cows on 11 farms had neutralizing antibodies to two bovine and three human rotavirus serotypes. After vaccination with one bovine rotavirus serotype, these cows produced a significant increase in antibody titers to these same five serotypes but not to two other serotypes to which they had no preexisting antibody. These results were interpreted to indicate that cows will respond heterotypically after monovalent vaccination to all rotavirus serotypes with which they have had experience and, therefore, that single serotype vaccination may be sufficient. This conclusion has practical importance for rotavirus immunization procedures.

Animals↗
PubMed1983

Prevalence of enterotoxigenic Escherichia coli in calves in Scotland and northern England.

Eighty-eight of 1529 (5.7 per cent) Escherichia coli isolates from diarrhoeic and clinically normal calves in Scotland and northern England were found to possess the K99 pilus antigen (K99+). There was complete correlation between possession of K99 antigen, heat stable enterotoxin production and ability to dilate intestinal loops. The diagnosis of calf enterotoxigenic E coli infections may therefore be based on the detection of K99 antigen alone. Enterotoxigenic E coli was isolated from 23 of 306 (7.5 per cent) diarrhoeic calves from eight of 70 (11.4 per cent) farms and was not isolated from clinically normal calves. Infected calves were between one and three days old. A survey by an enzyme-linked immunosorbent assay found 3.0 per cent and 3.9 per cent of sera from calves and cows respectively to contain antibodies to K99 antigen. The prevalence of other enteropathogenic organisms in calf faeces is also discussed.

Animals↗
PubMed1983

Development of calf diarrhoea vaccines.

Rotavirus and enterotoxigenic E. coli were found to cause approximately three-quarters of the total number of outbreaks of diarrhoea in young calves. Vaccinating pregnant cows with a combined vaccine of K99 antigen from E. coli and inactivated calf rotavirus stimulated secretion of specific antibodies in colostrum and milk. Calves born to vaccinated cows were completely protected against experimental enterotoxigenic colibacillosis. The efficacy of the rotavirus component is being investigated in field trials from which the early results look promising.

Animals↗
PubMed1982

Colostral and milk antibody titers in cows vaccinated with a modified live-rotavirus-coronavirus vaccine.

Colostral and milk whey rotavirus (RV) and coronavirus (CV) antibody titers stimulated in 15 beef heifers by vaccination with a modified live-RV-CV vaccine were compared with titers in 15 nonvaccinated heifers. Geometric mean antibody titers to RV in colostral and 3-day milk whey from vaccinated heifers were 2,807 and 92, respectively, and in control heifers were 1,613 and 71, respectively. Geometric mean antibody titers to CV in colostral and 3-day milk whey of vaccinated heifers were 877 and 13, respectively, compared with titers were 877 and 13, respectively, compared with titers in nonvaccinated heifers of 731 and 7, respectively. Differences in antibody titers between vaccinated and nonvaccinated heifers were not significantly different.

Animals↗
PubMed1982

Interaction of rotavirus and enterotoxigenic Escherichia coli in conventionally-reared dairy calves.

A study was made of the effects of rotavirus and/or enterotoxigenic Escherichia coli (ETEC) on dairy calves born and suckled on the farm and subsequently reared in isolation. Calves were orally inoculated at 6 days old with either rotavirus (5), ETEC (7), rotavirus and ETEC (5) or remained uninoculated controls (4), and their reactions were recorded by clinical, microbiological, and pathological observations. Rotavirus infection consistently produced diarrhoea, while ETEC inoculated alone did not colonise the intestine. In dual infections, both rotavirus and ETEC multiplied, although the severity of diarrhoea was not greater than that caused by rotavirus alone. Some ETEC-inoculated calves developed subsequent naturally-acquired rotavirus infections, but in these no ETEC multiplication occurred. The results suggest that prior or simultaneous rotavirus infection is necessary to enable ETEC colonisation of the intestine in conventional calves of this age.

Animals↗
PubMed1982

Passive immunity in calf diarrhea: vaccination with K99 antigen of enterotoxigenic Escherichia coli and rotavirus.

Twenty-four pregnant cows were vaccinated intramuscularly with K99 extract from enterotoxigenic Escherichia coli and inactivated rotavirus as follows: six cows were injected with 2 ml of oil-adjuvanted vaccine; six cows were injected with 0.5 ml of oil-adjuvanted vaccine; six cows were injected with 4 ml of aluminum hydroxide-adjuvanted vaccine twice with a four-week interval; and six cows were unvaccinated as controls. Calves born to these cows were challenged with enterotoxigenic E. coli at 6 to 18 h after birth. Serum and milk antibodies to K99 and rotavirus in cows vaccinated with either dose of oil vaccine were significantly increased until at least 28 days after calving. In cows vaccinated with alhydrogel vaccine, there was a significant K99 antibody increase in serum and in colostrum but not in milk and a significant rotavirus antibody increase only in colostrum. Five of six calves born to unvaccinated cows developed enterotoxic colibacillosis after challenge, and all excreted the challenge strain of enterotoxigenic E. coli. None of the 18 calves in the three vaccinated groups developed clinical colibacillosis, and fecal excretion of the challenge organism was reduced. A combined enterotoxigenic E. coli-rotavirus vaccine may prove useful in preventing some outbreaks of calf diarrhea.

Animals↗
PubMed1982

Experimental cryptosporidiosis in laboratory mice.

Eight strains of laboratory mice were susceptible to subclinical infections with Cryptosporidium sp. at 1 to 4 days of age, but only a transient infection could be established at 21 days of age or older. Immunosuppression of 21-day-old mice failed to render them more susceptible to infection. Laboratory storage conditions for Cryptosporidium sp. were investigated by titration in 1- to 4-day-old mice. Storage by freezing with a variety of cryoprotectants was unsuccessful, but storage at 4 degrees C in phosphate-buffered saline or 2.5% potassium dichromate was possible for 4 to 6 months.

Aging↗
PubMed1982

Rapid diagnosis of rotavirus infection by direct detection of viral nucleic acid in silver-stained polyacrylamide gels.

A rapid simple technique for the diagnosis of rotavirus has been developed based on the sensitive detection of rotavirus double-stranded RNA genome segments separated in polyacrylamide gels. The method utilizes a recently described ultrasensitive silver stain for polypeptides, which can also detect subnanogram amounts of nucleic acid. The sensitivity of the technique is comparable with that of electron microscopy or enzyme-linked immunosorbent assay.

Animals↗
PubMed1982

Diarrhoea in dairy calves reduced by feeding colostrum from cows vaccinated with rotavirus.

Forty-two dairy calves remained with their dams for two days after birth, and then were removed to a calf rearing shed. Calves were allocated to three groups for the next 14 days, and received twice daily either whole milk, whole milk with a 10 per cent supplement of pooled normal bovine colostrum or whole milk with 10 per cent supplement of colostrum from cows vaccinated with rotavirus. A natural outbreak of diarrhoea occurred, affecting 28 of the 42 calves. Feeding immune colostrum delayed the onset of diarrhoea, and reduced its incidence, duration and severity. Live weight gains were consequently improved. The group fed normal colostrum had diarrhoea intermediate in severity between that of control calves and those fed immune colostrum. The aetiology of the diarrhoea was complex, with calves excreting rotavirus, enteropathogenic Escherichia coli and cryptosporidia.

Animals↗
PubMed1982

Positive correlation between high aryl hydrocarbon hydroxylase activity and primary lung cancer as analyzed in cryopreserved lymphocytes.

Blood samples from closely monitored patients at the Veterans Administration Hospital in Houston, Texas, were collected, coded, and sent to Microbiological Associates over an 8-month period. Lymphocytes were isolated and cryopreserved at -190 degrees. Lymphocyte samples were simultaneously thawed, phytohemagglutinin activated, and analyzed for benz(a)anthracene-induced aryl hydrocarbon hydroxylase (AHH) levels, [3H]thymidine incorporation, and reduced nicotinamide adenine dinucleotide-dependent cytochrome b5 (cytochrome c) reductase activity. Determinations were made at both 96 and 120 hr in culture, and peak activities were compared among a total of 51 individuals who expressed such lesions as squamous cell carcinomas (22%), adenocarcinomas (14%), oat cell carcinomas (6%), chronic obstructive pulmonary disease (22%), and other nonmalignant diseases. Of the 14 highest AHH/cytochrome c activities observed, all were found in patients with primary lung cancer. Mean AHH/cytochrome c activities were 0.89 for lung cancer patients (a total of 21) and 0.47 for noncancer patients (a total of 30) (p less than 0.001). No relationship was observed between AHH/cytochrome c activity and age of patient, numbers of cigarettes smoked, family history of cancer, location or histological type of tumor, or level of phytohemagglutinin blastogenesis ([3H]thymidine cpm/cytochrome c). Whether the higher AHH levels are the cause or the result of the primary lung cancer remains to be determined.

Adult↗
PubMed1981

Inheritance of Escherichia coli K88 adhesion in pigs: identification of nonadhesive phenotypes in a commercial herd.

A method for preparing fragments of brush border from the small intestinal epithelial cells of pigs was modified so that specimens as small as 3 mm X 3 mm could be used. This modification also allowed more rapid preparation and the brush borders thus prepared adhered specifically to K88+ but not K88- Escherichia coli. At slaughter 12.2 per cent of 459 bacon weight pigs from a commercial herd were of nonadherent phenotype. Litters containing only nonadherent pigs were identified. Parents of these litters and siblings intended for breeding stock replacements could be identified as probably also being of nonadherent phenotype and this was confirmed by examining biopsy samples obtained by enterotomy from the siblings.

Adhesiveness↗
PubMed1981

IgG1 antibody in milk protects lambs against rotavirus diarrhoea.

Newborn gnotobiotic lambs were fed a diet of diluted evaporated milk supplemented either with normal ewes' milk or with milk obtained from ewes injected parenterally during gestation with rotavirus. Lambs fed 150 ml per day of milk collected 5 days after lambing from normal ewes were susceptible to rotavirus infection and diarrhoea, while lambs fed milk from vaccinated ewes collected either 5 or 12 days after lambing were protected. Analysis of the milk by column chromatography showed the anti-rotavirus activity to be in the fractions containing IgG1.

Animals↗
PubMed1981

Purification and characterization of ovine astrovirus.

Astrovirus, purified in aggregated form from epithelial cells of the small intestinal villi of infected gnotobiotic lambs, was shown to have a single-stranded RNA genome with an S value of 34 and poly(A) tract. Only two major capsid polypeptides were detected with similar mol. wt. of approx. 3.3 x 10(4).

Animals↗
PubMed1981

Lactose tolerance in lambs with rotavirus diarrhoea.

It has been suggested that lactose malabsorption is an important factor in producing the diarrhoea of acute rotavirus infection. Accordingly, the lactose tolerance of gnotobiotic newborn lambs, infected with lamb rotavirus, has been investigated by clinical studies and tissue enzyme assays. Although lactase activity is low in affected areas of the small intestine, rotavirus infected lambs are not lactose intolerant as assessed by the measurement of reducing substances in the faeces, or by the clinical effects and blood glucose levels after a 5.8 mmol (2 g)/kg lactose load on the second day post-infection. Lactose intolerance could be demonstrated by using extremely high (29.2 mmol (10 g)/kg) doses of lactose, three or four times the normal dietary lactose intake. These experiments suggest that lactose-containing feeds (such as maternal milk) are not necessarily contraindicated in patients or animals with rotavirus diarrhoea.

Animals↗