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Biomedical subjects

C L Gyles

Publications and source records attributed to C L Gyles.

At least 73 records · Page 4Linked to original sources
PubMed1986

Galactose epimeraseless mutants of Salmonella typhimurium as live vaccines for calves.

The purpose of the study was to evaluate the safety and efficacy of a galactose epimeraseless mutant of Salmonella typhimurium administered as an oral vaccine to one week old calves and to investigate properties of galactose epimeraseless mutants which affect their virulence and immunogenicity. The galactose epimeraseless mutant S. typhimurium strain G30D caused diarrhea and fever in three calves to which it was administered orally at a dose of 10(10) organisms; all three calves died following challenge with virulent S. typhimurium ten days postvaccination. Mild illness developed in four calves vaccinated with a dose of 9 X 10(6) organisms and one of these calves survived challenge. Three unvaccinated calves died following challenge. The vaccine organism persisted in tissues and was shed for a prolonged period by calves which received 10(10) organisms. Studies of characteristics of galactose epimeraseless mutants of S. typhimurium showed that, in the presence of galactose, there is selection for secondary mutants which are galactose resistant. The studies indicate that galactose epimeraseless mutants of S. typhimurium are not good candidate live vaccine organisms for use in calves.

Animals↗
PubMed1985

Enterotoxin plasmids in bovine and porcine enterotoxigenic Escherichia coli of O groups 9, 20, 64 and 101.

Fourteen strains of Escherichia coli of serogroups characteristic of porcine class 2 enterotoxigenic E. coli isolated from pigs or calves were selected for genetic studies. The strains were examined for their ability to cotransfer a number of plasmid-mediated properties during conjugation with E. coli K-12. These properties were antibiotic resistance, and the production of heat-stable enterotoxin, the K99 antigen and colicin and the ability to ferment raffinose. Distinction was made between the two types of heat-stable enterotoxin, STa and STb. All 14 strains were antibiotic resistant and 11 of them cotransferred antibiotic resistance and heat-stable enterotoxin. One strain which transferred heat-stable enterotoxin also transferred the raffinose gene. Among six K99-positive strains which transferred heat-stable enterotoxin, five always cotransferred K99. Three strains had 100% cotransfer of colicin as well as heat-stable enterotoxin and K99. Drug resistance determinants were cotransferred at high frequency with heat-stable enterotoxin for six of eight multiple drug resistant enterotoxigenic E. coli. A 100% cotransfer of combinations of heat-stable enterotoxin, K99, colicin and antibiotic resistance was often associated with a single plasmid band on agarose gel electrophoresis. For some strains, the genes for STa and STb were on the same plasmid and for others they were on separate plasmids. The enterotoxin plasmids ranged in size from 5.2 to 85 Mdal. Heterogeneity in molecular size occurred among enterotoxin plasmids in E. coli of the same serogroup and recovered from the same animal host species.

Animals↗
PubMed1985

Linkage of genes for heat-stable enterotoxin, drug resistance, K99 antigen, and colicin in bovine and porcine strains of enterotoxigenic Escherichia coli.

Linkages among genes for production of Escherichia coli heat-stable enterotoxin (ST), drug resistance, K99 antigen, and colicin were investigated in 2 bovine and 3 porcine strains of enterotoxigenic E coli. In conjugation experiments, all 5 isolates transferred enterotoxigenicity and the ability to produce K99; 4 of the 5 isolates also transferred antibiotic resistance markers, and 3 colicinogenic strains transmitted the ability to produce colicin. In 2 of the 3 colicin-producing strains, the genes for colicin were located along with those for K99 and ST on a single plasmid. One of these 2 strains transferred the genes for tetracycline resistance and production of both mouse-active ST (STa) and mouse-inactive ST, whereas the other transmitted the gene(s) for STa only. Transformation studies with the 3rd strain revealed that the K99 determinant resided on a 22-megadalton (Mdal)R plasmid, and that STa and colicin production were on a 65-Mdal plasmid. Analysis of the plasmids from the transformation experiments revealed that the larger plasmid was conjugative and the smaller plasmid was nonconjugative; stable cointegrate formation occurred between these 2 plasmids. Genetic information coding for the production of STa and K99 were also present on a single plasmid of approximately 80 Mdal in both noncolicinogenic strains.

Animals↗
PubMed1984

Resistance to drugs and heavy metals, colicin production, and biochemical characteristics of selected bovine and porcine Escherichia coli strains.

A study was made of resistance to heavy metals and antibiotics, biochemical characteristics, and colicinogeny in selected strains of Escherichia coli of O serogroups 8, 9, 20, 64, 101, and X46. Of 42 strains that were investigated, 26 were porcine enterotoxigenic E. coli (ETEC), 8 were porcine non-enterotoxigenic E. coli (NETEC), and 8 were bovine ETEC. Multiple resistance to antimicrobial agents was common among the strains, and resistance to chloramphenicol and kanamycin was less common than resistance to other drugs, possibly reflecting the lower frequency of use of these agents in pigs and calves. Colicin production was a more common property of porcine ETEC (80.8%) than of porcine NETEC (25%), and all porcine ETEC of O serogroups 101 and 64 were colicinogenic. Equal numbers of bovine ETEC strains were colicinogenic as were non-colicinogenic. Resistance of bovine and porcine strains to sodium arsenate, mercury, and tellerium was 90, 16, and 5%, respectively. There was a close relationship between serogroup and biochemical reactions among the E. coli strains tested.

Animals↗
PubMed1983

Characterization of the gene encoding heat-stable toxin II and preliminary molecular epidemiological studies of enterotoxigenic Escherichia coli heat-stable toxin II producers.

The gene encoding heat-stable toxin II (STII) was cloned into an Escherichia coli K-12 strain, and its nucleotide sequence was determined. The deduced amino acid sequence indicates that STII is synthesized within the cell as a 71-amino-acid protein and that neither the DNA nor amino acid sequence bears any similarity to that of heat-stable toxin I. A DNA fragment containing the STII gene was used to probe enterotoxigenic E. coli clinical isolates with various toxin phenotypes and was shown to be useful in detecting all STII and only STII producers.

Amino Acid Sequence↗
PubMed1983

Relation of lipid content and exotoxin production to virulence of Corynebacterium pseudotuberculosis in mice.

Twenty-five isolates of Corynebacterium pseudotuberculosis from lesions of caseous lymphadenitis in goats were examined for cell wall lipid content, exotoxin production, and virulence in mice. The mean percentage of lipid content was 6.52% and significant (P less than 0.005) differences were demonstrated between some isolates. Exotoxin in broth culture filtrates of the 25 isolates was measured by the staphylococcal beta-hemolysin inhibition (BHI) test and a radioassay for phospholipase D. All isolates were positive for exotoxin in both tests and 1 isolate had higher activity than the others. Because the correlation between the BHI test and radioassay was poor, it may be that the radioassay detects only enzymatically active exotoxin, whereas the BHI test detects active and inactive exotoxin. All isolates were virulent in mice at 2 dosage levels used to produce subacute-chronic and acute disease. Differences in virulence among isolates were detected only at the lower dosage level. There was a direct relationship between percentage of lipid and induction of chronic abscessation in mice, but not between lipid content and mortality. Although exotoxin production in vitro could not be related quantitatively to virulence, the results of inoculating mice with bacterial cells and broth culture supernatant were consistent with a role for exotoxin in disease.

Animals↗
PubMed1982

The role of K antigens of enteropathogenic Escherichia coli in colonization of the small intestine of calves.

The colonizing and proliferating abilities of enterotoxigenic acapsular or K99- mutants of bovine enteropathogenic Escherichia coli strains were compared with those of their capsulated and K99+ parent strains in the small intestine of infected colostrum-fed calves. Calves infected with the enteropathogenic E. coli parent strains developed profuse diarrhea and severe dehydration. None of the calves which received the acapsular mutant developed diarrhea and one of three calves inoculated with the K99- enterotoxigenic mutant developed moderate diarrhea. The parent enteropathogenic E. coli strains colonized the middle and lower small intestine; in these areas a layer of specific immunofluorescence against the enteropathogenic E. coli covered most villi and 80% of the organisms were associated with the intestinal wall. The acapsular mutant strain failed to colonize the small intestine and fluorescent bacteria were not observed in any area of the small intestine. The K99- mutant proliferated to a lesser extent than did the K99+ parent strain in all areas of the small intestine but moderately colonized the lower small intestine where fluorescent bacteria were observed to cover parts of the intestinal villi.

Animals↗
PubMed1982

The pathogenicity of Yersinia enterocolitica strains isolated from various sources in four test systems.

Six tests were applied to 39 strains of Yersinia enterocolitica of various serotypes and from several sources in an attempt to relate the test to pathogenicity of the strains. The tests that were used were the pig gut loop test and the infant mouse test for heat stable enterotoxin, the Sereny and HeLa cell tests for invasiveness, inhibition of growth on magnesium oxalate agar, and the ability to cause diarrhea in infant mice. The pig gut loop test was found to be unsuitable for detection of heat stable enterotoxin but 20 strains produced heat stable enterotoxin that was detected in infant mice. None of the strains was positive in the Sereny test but 21 invaded HeLa cells. The growth of 20 strains was inhibited at 37 degrees C on magnesium oxalate agar and, in the orally-infected mice, 23 strains caused diarrhea or death. These findings indicate a discrepancy between the infant mouse test and the ligated intestine test in pigs for heat stable enterotoxin and a significant difference in Y. enterocolitica heat stable enterotoxin compared with Escherichia coli heat stable enterotoxin because the former failed to elicit a significant response in pig intestine.

Animals↗
PubMed1982

Scanning and transmission electron microscopic study of the small intestine of colostrum-fed calves infected with selected strains of Escherichia coli.

Colostrum-fed calves were fed milk replacer containing 10(11) enteropathogenic Escherichia coli (EEC) or nonenteropathogenic E coli (NEEC). The NEEC failed to colonize the small intestine or to be associated with the intestinal wall. The EEC colonized the middle and caudal portions of the small intestine, and in these areas, 80% of the organisms were associated with the intestinal wall. Light, immunofluorescence, scanning, and transmission electron microscopic studies demonstrated a layer of EEC adherent to the mucosal surface of the jejunum and ileum of infected calves. Transmission electron microscopy revealed that each EEC was surrounded by an electron-lucent zone and that some organisms had dense fuzzy surface structures which resembled pili. In the staining with ruthenium red, the electron-lucent areas were occupied by thick capsular material which seemed to be in contact with the microvilli. In some areas of contact with EEC, the microvilli were elongated and projected into the intestinal lumen. Light microscopy demonstrated stunted, thickened, and fused villi with the lamina propria expanded by inflammatory infiltrate. Changes in the villous surface topography, such as denudation of the tips of the villi and exposure of the lamina propria into the lumen, were observed by light and scanning microscopies in samples taken after death of the calves, but not in adjacent samples removed from calves under general anesthesia.

Animals↗
PubMed1982

Characterization of strains of corynebacterium pseudotuberculosis.

Twenty-five strains of Corynebacterium pseudotuberculosis isolated from lesions of caseous lymphadenitis in goats were examined for their biochemical characteristics, antimicrobial susceptibility, and phospholipase D activity. The strains were uniform in biochemical reactions, cultural characteristics, and susceptibility to antimicrobial agents. Presence of urease and phospholipase D and absence of pyrazinamidase were valuable criteria in the identification of C. pseudotuberculosis.

Animals↗
PubMed1980

Genetic and molecular characteristics of Vir plasmids of bovine septicemic Escherichia coli.

Three wild strains of bovine septicemic Escherichia coli were selected on the basis of their production of a toxin lethal for mice and chickens and their characteristic surface antigen. The transfer of these virulence (Vir) properties from two of the three to recipient E. coli was detected after mating. One Vir plasmid (pJL1) was derepressed for transfer and associated with mobilization of chromosomal markers. The other, pJL2, was repressed. Both plasmids were tagged with transposon Tn5 (kanamycin resistance), and transfer parameters of the tagged plasmids were studied. The Tn5 insertion in pJL2 usually increased transfer efficiency 100-fold. Plasmid pJL1 was classified as a member of the FIV incompatibility group. A pJL1::Tn5 derivative plasmid was incompatible with ColV1. Plasmid pJL2 behaved as an fi+ plasmid. Both plasmids pJL1 and pJL2 had a molecular weight of 92 x 10(6) and were present at about four copies per chromosome; their deoxyribonucleic acid (DNA) structures were not identical on the basis of restriction enzyme analysis. DNA-DNA hybridization revealed a polynucleotide sequence homology of at least 58% between the two plasmids. No plasmids could be detected in one wild or certain laboratory-derived Vir+ E. coli strains.

Animals↗
PubMed1980

Escherichia coli heat-stable enterotoxin in feces and intestines of calves with diarrhea.

Two experiments were conducted to evaluate detection of Escherichia coli heat-stable enterotoxin (ST) in the feces of calves as a method for implicating E coli in neonatal calf diarrhea. The first experiment evaluated the use of the infant mouse test for detection of ST in the feces of calves with naturally occurring diarrhea. Simultaneous identification of bovine enteropathogenic strains of E coli (EEC) and of other infective agents implicated in neonatal calf diarrhea was attempted in these samples. The ST was detected with certainty in only 7 of 41 samples from calves less than or equal to 3 weeks old. Enteropathogenic E coli, however, was detected in 27 samples. In 23 of these 27 samples, EEC was the only recognizable diarrheagenic agent. In a small percentage of the samples, Salmonella, rotavirus, coronavirus, and cryptosporidium were recognized alone, in combination with each other, or with EEC. In the second experiment, 6 calves were fed colostrum from cows inoculated with the bovine EEC strain B44; 6 were given colostrum from cows vaccinated with non-EEC strain 28F, and 4 were given milk from nonvaccinated heifers. Two of the calves that were given colostrum from cows inoculated with strain B44 were challenge exposed with the non-EEC strain 28F. The remaining calves were challenge exposed with the EEc strain B44. Fecal samples were taken from these calves at intervals and were examined for the presence of ST and of the challenge-exposure organism. The ST was detected in approximately one half of the fecal samples obtained, and it was most often detected in the early stages of the induced diarrhea. Calves were observed to shed the challenge-exposure EEC strain for long periods in the absence of diarrhea or detectable amounts of ST in the feces. The ST was detectable in fecal samples when the diarrhea was severe and when the dry matter content of the fecal samples was low.

Animals↗
PubMed1980

Occurrence of the vir plasmid among animal and human strains of invasive Escherichia coli.

Forty-six isolates of Escherichia coli recovered from systemic diseases in animals and persons were studied to determine which isolates possessed properties attributed to the Vir plasmid. These properties were production (i) of a chick letha toxin and (ii) of a specific surface antigen. Neither toxic activity nor surface antigen production could be detected in nine E coli strains from septicemia in chickens and 11 from human cerebrospinal fluid. Two of 8 strains from human septicemic disease and 3 of 18 isolates from calf septicemia produced the toxin, but lacked the characteristic surface antigen. Two of the 18 bovine strains had both characteristics. Several methods of screening for Vir+ transconjugants were investigated in an attempt to facilitate their recognition after mating a Vir+ donor with a suitable recipient. These methods, which included precipitation in agar plates containing antiserum, immunodiffusion tests, and fluorescent antibody tests, were unsuccessful. It was observed, however, that the pattern of growth in tryptic soy broth of the Vir+ transconjugants was usually different from that of the Vir- clones. Vir+ transconjugants grew as a heavy sediment with a clear supernatant, whereas their Vir- counterparts showed a uniform turbidity. When the Vir plasmid was transferred to an E coli strain which lacked appendages, fimbriae were observed to be associated with the presence of the plasmid. Two types of fimbriae were evident. One type appeared to be sex fimbriae and the other was probably the surface antigen associated with the Vir phenotype.

Animals↗
PubMed1979

Limitations of the infant mouse test for Escherichia coli heat stable enterotoxin.

A study was undertaken to evaluate the response of different test systems to preparations of heat-stable enterotoxin (ST) derived from Eschericihia coli strains recovered from diarrheal disease of humans, pigs and calves. Sterile broth culture supernatants of enterotoxigenic strains of E. coli were heated at 65 degrees C for 30 minutes and tested for the presence of heat-stable enterotoxin. Three test systems, namely, ligated intestine of weaned pigs, ligated intestine of rabbits and the infant mouse test were used in attempts to detect ST in the culture supernatants. Two patterns of reaction were observed in response to ST-containing preparations: either the preparation elicited a response in the three tests or the preparation elicited a reaction only in the ligated pig intestine. A response in all three tests were observed for 5/5 human ST-producing E. coli, 5/5 bovine enterotoxigenic E. coli, 5/5 "atypical" porcine enterotoxigenic E. coli, 3/3 St(+)LT(-) porcine E. coli of serogroup O138:K81 and 4/24 LT(+)ST(+) porcine E. coli. A response only in the ligated pig intestine was obtained with 5/5 ST(+)LT(-) porcine E. coli belonging to serogroups other than O138:K81 and to 20/24 ST(+)LT(+)E. coli from pigs. The results are consistent with the view that there are two kinds of ST, one of which (ST1) reacts in all three tests and the other (ST2) which reacts only in the ligated pig intestine. The findings underscore the limitations of the infant mouse test as a means of detecting ST in porcine isolates of E. coli, since the test fails to detect ST produced by a large number of these E. coli strains. There appeared to be a relationship between kind(s) of ST produced and the animal species from which the producing organism was recovered.

Animals↗
PubMed1978

Isolation and characterization of enterotoxin-deficient mutants of Escherichia coli.

The genes controlling the production of two types of enterotoxin of Escherichia coli, one heat-labile (LT) and the other heat-stable (ST), are found on plasmids. The absence of a direct selection procedure has made it difficult to isolate mutants affecting toxin production. However, the availability of a naturally occurring "recombinant" plasmid, carrying genes for LT and ST formation and also for resistance to tetracycline, streptomycin, and sulfonamides, made it possible to use comutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine to enrich for such mutants. We have isolated and characterized 58 LT- mutants and 7 ST- mutants. Among the LT- group we found amber mutants, temperature-sensitive mutants (most of which produce unusually heat-labile LT), and "leaky" mutants with reduced LT activity. The majority of the tested LT- mutants produced immunologically crossreacting material, in most cases in wild-type amounts. Among all 17 of the LT- mutants that could be transferred, the mutation was found to be on the plasmid. In contrast, only one of four transferrable ST- mutants appeared to be a plasmid mutant.

Bacterial Toxins↗
PubMed1978

Characterization of plasmids that encode for the K88 colonization antigen.

K88 antigen, and important virulence factor in porcine enteropathogenic Escherichia coli (EEC), can be transferred along with the ability to ferment the trisaccharide raffinose (Raf). The plasmids from a number of EEC strains that encode these two properties were isolated and characterized. In most strains the K88 and Raf genes were found on a single nonconjugative plasmid approximately 50 x 10(6) daltons in size. This plasmid core was conserved with only slight variation among the strains tested. In some transconjugants, larger conjugative plasmids were observed that were apparently recombinants between the Raf/K88 plasmid and a transfer fa(tor. Occasionally plasmids carrying only the raffinose fermentation genes arose by deletion of a deoxyribonucleic acid segment of about 20 x 10(6) daltons that included the K88 antigen gene(s).

Animals↗