Search PubMed⌕ Search

Biomedical subjects

C Wray

Publications and source records attributed to C Wray.

At least 127 records · Page 7Linked to original sources
PubMed1978

Passive protection of lambs against experimental enteric colibacillosis by colostral transfer of antibodies from K99-vaccinated ewes.

Pregnant ewes were vaccinated with partially purified, cell-free K99 antigen isolated from an enteropathogenic strain of Escherichia coli, strain B41 (O101:K99:NM), to induce passive immunity via the colostrum in their offspring against an oral challenge with heterologous "calf-lamb" enteropathogenic strains of E. coli B44. After sucking their dams, lambs were dosed orally with 7X10(10)-2.2 X10(11) organisms within 4--21 h of birth. One group of 10 lambs was dosed with cultures of the mucoid (O9:K30(A),K99:NM) form of strain B44 and another group of 10 lambs with the non-mucoid (O9:K99:NM) form; two groups of four control lambs from unvaccinated dams were similarly challenged. All four control lambs challenged with mucoid B44, loose feaces were detected in only two of the four control lambs and in none of the lambs from vaccinated dams. This suggests that the polysaccharide K antigen may contribute to the virulence of "calf-lamb" enteropathogenic strains that possess the K99 antigen. However, lambs passively immunised with colostrum from dams vaccinated with K99 antigen alone were protected against the production of enteric colibacillosis by oral challenge with EPEC strain B44.

Animals↗
PubMed1978

Experimental Salmonella typhimurium infection in calves.

The paper describes the clinical, bacteriological and pathological findings in experimental Salmonella typhimurium infection in calves. Oral doses of 10(8) and 10(9) organisms produced clinical disease and high mortality; doses ranging from 10(4)--10(7) organisms were less consistent in their action. Jersey calves appeared more susceptible to infection than Friesian calves. The clinical signs in most calves were pyrexia and a characteristic diarrhoea that lasted for up to 11 days; more severe symptoms were seen in the calves that received the higher doses. Following infection, all calves excreted S typhimurium in their faeces, the highest counts being observed in the calves that died. In the calves that survived, counts ranging from 10(2)--10(5)/g faeces occurred continuously for up to a maximum of 20 days and subsequent intermittent excretion occurred in a number of calves. In the calves that died, necrotic enteritis in the ileum and large intestine was the most striking lesion; lesions were uncommon in other organs. The findings are discussed in relation to the pathogenesis, diagnosis and control of the disease.

Animals↗
PubMed1977

The immunization of mice and calves with gal E mutants of Salmonella typhimurium.

A galactose epimeraseless (gal E) mutant of Salmonella typhimurium was investigated in mice and calves for its suitability as a live vaccine. In mice, a very highly significant difference in the mortality rates was observed when vaccinated and non-vaccinated animals were challenged with virulent strains of S. typhimurium and S. dublin. In calves, doses of 10(6) and above of gal E mutant injected subcutaneously provided highly significant protection both in terms of mortality and prevalence of symptoms when calves were challenged orally with S. typhimurium. However, there appeared to be a relation between the vaccine and the presence of renal lesions and before gal E mutants can be recommended, further work is necessary to determine the pathogenesis of these lesions.

Animals↗
PubMed1977

Incidence of salmonella infection in animals in England and Wales 1968--1974.

Of a total of 23,609 incidents of salmonella infection reported during the period 1968--74, 20,326 occurred in cattle, 1744 in poultry and other birds, 675 in sheep, 558 in pigs and 306 in other species of animals. Despite the large number of serotypes isolated (153), 88% of incidents were due to only two stereotypes: S. dublin (15,929 incidents of which 15,446 occurred in cattle ) and S. typhimurium (4842 incidents of which 3785 occurred in cattle and 732 in birds). S. choleraesuis was the third (314 incidents which with only 5 exceptions occurred in pigs) and S. abortusovis (243 incidents all in sheep) was the fourth most commonly isolated serotype. The following six serotypes were each recorded in more than 100 incidents: S. newport (177), S. agona (170), S. virchow (169), S. anatum (152), S. enteritidis (150) and S. montevideo (111). The other 143 serotypes accounted for only 5-8% of total incidents. The trends of annual incidence of salmonella infection in cattle, sheep, pigs, poultry and other birds during the 17-year period 1958-74 and the distribution of the main serotypes in the individual species of animals from 1968 to 1974 are discussed.

Animals↗
PubMed1976

The effect of T and B lymphocyte depletion on the protection of mice vaccinated with a Gal E mutant of Salmonella typhimurium.

Immunosuppressive agents were used to determine the relative importance of T and B lymphocytes in conferring protection to mice vaccinated with a live gal E mutant of Salmonella typhimurium, strain G30D. Lymphocyte transformation and serum agglutination tests showed that while cyclophosphamide (CPA) suppressed B lymphocytes, antilymphocyte sea (ALS) suppressed both T and B cells. The humoral response of vaccinated animals treated with ALS was therefore supplemented by the i.v. injection of serum from untreated vaccinated mice. CPA-treated mice could not control multiplication of the vaccinal strain which eventually killed them. There was little multiplication of the vaccinal strain in the controls and ALS-treated mice, all of which survived to challenge. The vaccinated controls and vaccinated ALS treated groups each survived infection with the challenge strain which was gradually eliminated. It was concluded that humoral immunity was of greater importance than cellular immunity in mice vaccinated i.p. with strain G30D.

Animals↗
PubMed1976

A study of the complement fixation test in Salmonella dublin infection.

The complement fixation test was evaluated in a study of Salmonella dublin infection in cattle. In calves vaccinated with a live S dublin vaccine at three days of age, complement fixing (CF) antibodies were not detected in colostrum-fed calves although CF antibodies were detected at low titre in colostrum-deprived calves. In calves vaccinated at three months of age and in experimentally infected cows, CF antibodies persisted for three to six months but serum agglutinin (SA) antibodies persisted at diagnostic titres for longer periods. When serum samples from outbreaks of S dublin infection were examined, the CF results were in agreement with the SAT in the majority of samples obtained from adults and calves suffering from enteric disease. In samples from cases of S dublin abortion, a number of samples had negative CF titres although the SA titres were indicative of infection. Non-specific CF reactions occurred in serum samples from cattle infected with salmonella serotypes other than S dublin.

Agglutination Tests↗
PubMed1975

Factors influencing occurrence of colibacillosis in calves.

This investigation describes some of the husbandry factors influencing the occurrence of colibacillosis in calves. Diarrhoea and mortality were usually associated with an increase in the proportion of "pathogenic" to total E coli to about 50 per cent in the faeces although there were occasions when the proportion of "pathogenic" E coli increased but no disease occurred. These increases often followed changes of diet which appeared to be more important than environmental conditions. The use of uncontaminated houses to break the cycle of infection appeared to have the greatest influence on the disease pattern.

Animals↗
PubMed1975

Studies on the development of chloramphenicol resistance in Salmonella typhimurium.

Chloramphenicol therapy of acute and chronic Salmonella typhimurium infection in mice did not lead to the development of chloramphenicol resistant mutants of this organism. However, chloramphenicol resistant organisms were readily produced in vitro. Transfer of chloramphenicol resistance from a donor strain of Escherichia coli X12 to a suitable recipient strain of S typhimurium 5235 occurred readily in the intestine of 15 out of 20 conventional mice, following oral administration of large doses of these strains supplemented by chloramphenicol therapy. When a similar system was used in untreated animals, only a small number of chloramphenicol resistant S typhimurium were isolated from three out of 18 mice. The virulence of chloramphenicol resistant S typhimurium produced in vitro and in vivo was similar to that of the sensitive parent strain.

Animals↗