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Biomedical subjects

G W Pugh

Publications and source records attributed to G W Pugh.

At least 55 records · Page 3Linked to original sources
PubMed1980

Infectious bovine keratoconjunctivitis: effects of vaccination on Moraxella bovis carrier state in cattle.

A study was conducted to determine whether vaccination of cattle while they were undergoing an acute episode of infectious bovine keratoconjunctivitis (IBK), would cause vaccinated cattle to abort Moraxella bovis infection sooner than nonvaccinated cattle. Fourteen calves were allotted into two groups of seven calves each, and the eyes of each calf were exposed to a virulent culture of M bovis. Twenty days after calves were infected and showing signs of IBK, seven calves were vaccinated with M bovis pilus vaccine made from the exposure strain. Ocular and nasal discharges were collected and examined for M bovis for 64 days. Most calves developed signs of IBK after exposure and all but one calf (nonvaccinated) developed ocular infection with M bovis. The mean number of days (33 and 33.3, respectively) of ocular infection was not significantly (P = 0.05) different in the vaccinated calves than in the nonvaccinated calves. The eyes of the calf that did not become infected with M bovis were infected with nearly a pure culture of Escherichia coli. This calf failed to develop ocular infection, but had M bovis in its nasal discharge throughout the study (64 days). Moraxella bovis was isolated from the nasal discharge of other calves only when there were concurrent ocular infections.

Animals↗
PubMed1980

Wavelength of ultraviolet radiation that enhances onset of clinical infectious bovine keratoconjunctivitis.

Cellulose acetate filtered ultraviolet (UV) radiation and unfiltered UV radiation were used on calves that were subsequently challenge exposed with Moraxella bovis. The onset, course, and severity of infectious bovine keratoconjunctivitis (IBK) were studied. Ten calves irradiated with unfiltered UV had the disease 1 to 2 days after M bovis challenge exposure; all 10 calves had moderate to severe IBK. Ten calves irradiated with filtered UV and 10 calves not irradiated manifested IBK in a similar manner. The date of onset and severity of the disease varied. Evidence is presented to support the contention that the wavelengths (around 270 nm) which are eliminated by cellulose acetate enhance the course of IBK. The effects on IBK of environmentally increased solar UV radiation is also discussed.

Animals↗
PubMed1979

Identification of colonies of Moraxella bovis by plate epi-immunofluorescence.

A modification of the plate epi-immunofluorescence test was found to be a reliable method for the positive identification of colonies of Moraxella bovis when fluorescein isothiocyanate-conjugated globulin prepared against pili from selected strains of M bovis was used. A cross-reaction with other members of the genus Moraxella or other moraxella-like organisms was not observed, except with an equine Moraxella sp, which produced a weak reaction.

Culture Media↗
PubMed1979

Comparison of vaccination and treatment in controlling naturally occurring infectious bovine keratoconjunctivitis.

A vaccination study for infectious bovine keratoconjunctivitis was conducted on 108 newborn Hereford calves in the US Department of Agriculture Meat Animal Research Center cattle herd at Clay Center, Nebraska. Groups were allocated so that age of calf, sex of calf, and age of dam were equally distributed between the 54 vaccinated (group I) and the 54 nonvaccinated (group 2) control calves. The dams of both groups of calves were monitored as group 3 controls. An autogenous Moraxella bovis bacterin (formalin-killed, whole cells) was given IM at birth and at approximate intervals of 2 weeks for a total of 3 doses. Bacterial isolation rates for the cattle in groups 1, 2, and 3 during the summer were 92.6%, 92.6%, and 54.1%, respectively, and disease rates were 100%, 96.3%, and 70.6%. The rates were significantly (P less than 0.05) different between calves and cows. Vaccination of calves at birth permitted serum antibodies to develop before the calves were extensively exposed to infection; however, immunity to the disease did not develop. In a treatment study of other animals in the same herd, but in another pasture, the same criteria were used for allocation of 107 cow-calf pairs. Eye spray was applied to treated principals (group 4, 52 calves; and group 6, 53 cows) each week after examination and sample collection. Controls consisted of 54 calves (group 5) and 54 cows (group 7) that were examined and cultured bacteriologically in the same manner. The bacterial isolation and disease rates were less (P less than 0.05) in the treated calves (group 4) than in the nontreated controls (group 5). The differences in bacterial isolation rates between groups 6 and 7 were not significant, but group 6 had less (P less than 0.05) grade III lesions than did group 7. Weekly treatment appeared to be more effective in reducing the incidence of disease than did vaccination.

Age Factors↗
PubMed1979

Biological effect of ultraviolet radiation on cattle: bovine ocular squamous cell carcinoma.

The relationship between bovine ocular squamous cell carcinoma and ultraviolet radiation was studied. Experimental procedures were devised to irradiate cattle with predetermined quantities of ultraviolet beta. Irradiation induced a preneoplastic ocular growth in one of four irradiated cattle. An epizootiologic study indicates that since 1950 the occurrence of bovine ocular squamous cel carcinoma reported at slaughter has increased. This increase was real and not due to an increase in numbers of cattle.

Animals↗
PubMed1978

Serologic response of vaccinated cattle to strains of Moraxella bovis isolated during epizootics of keratoconjunctivitis.

In studies to determine whether there were antigenic differences between strains (isolates) of Moraxella bovis, the sera from vaccinated calves were tested with isolates of M bovis while the calves were experiencing epizootics of infectious bovine keratoconjunctivitis (IBK). Before the epizootics of IBK, the calves were intramuscularly vaccinated with a formalin-killed autogenous M bovis bacterin. During the epizootics, the eyes were examined by cultural technique, and isolates which were obtained were categorized by catalase activity, source (diseased or nondiseased eyes), and reactivity with the various sera. The serum reactivity of the isolates was compared with that of the vaccinal strain. The vaccinal strain and 8 of the 1 5 selected isolates obtained during the 1974 epizootic were catalase negative. Seven of the 15 isolates from the 1974 epizootic and all of the selected isolates from the 1975 epizootic were catalase positive. A significantly higher (P less than 0.01) percentage of calf sera were serologically reactive with the vaccinal strain and other catalase-negative isolates (45.0%) than with catalase-positive isolates (34.8%). The results, although not definitive, suggest that there may be antigenic differences among strains of M bovis. These differences should be considered when cattle are vaccinated against IBK under natural conditions of exposure.

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PubMed1977

Experimentally induced infections bovine keratoconjunctivitis: effectiveness of a pilus vaccine against exposure to homologous strains of Moraxella bovis.

A study was conducted to determine whether vaccination with sonicated pili of Moraxella bovis would protect cattle from subsequent infection and disease when experimentally challenged by exposure to homologous cultures of M bovis. Some calves were intramuscularly inoculated 2 times with pili of M bovis suspended in water, and others were subcutaneously inoculated 2 times with pili of M bovis suspended in oil; 21 days were allowed between inculations. Controls were nonvaccinated calves. Fourteen days after the last inculation, all calves were exposed to virulent homologous cultures of M bovis. The results indicated that vaccination with sonicated pili of M bovis may induce protective immunity against homologous strain challenge exposure. Vaccines in oil that were injected subcutaneously protected to a greater extent than did vaccines in water that were injected intramuscularly. The development of inflammatory nodules at the site of inoculation was associated with resistance to infection and disease. Only 1 of the vaccinated calves that resisted disease lacked precipitating antibodies against sonicated pili at the time of the challenge exposure. This calf had antibodies 2 weeks later.

Animals↗
PubMed1977

Induced infectious bovine keratoconjunctivitis: vaccination with whole cell bacterins of Moraxella bovis mixed with Freund's incomplete adjuvant.

Our studies on vaccination against infectious bovine keratoconjunctivitis were extended to include the use of adjuvant bacterins. Seventeen calves were given 2 doses of killed Moraxella bovis mixed with Freund's incomplete adjuvant; 15 calves were given 2 doses of whole cell bacterin without adjuvant. Four weeks later, all vaccinated and non-vaccinated (control) calves were challenge exposed by the conjunctival administration of virulent M bovis. The incorporation of Freund's incomplete adjuvant did not enhance the immunogenicity of M bovis bacterin for protection of calves against infectious bovine keratoconjunctivitis. Results indicated that the use of Freund's incomplete adjuvant does not compensate for a reduction in the number of doses which are required for protective vaccination of cattle.

Animals↗
PubMed1976

Experimental production of infectious bovine keratoconjunctivitis: comparison of serological and immunological responses using pili fractions of Moraxella bovis.

The effect of vaccinating cattle and mice on the development of keratoconjunctivitis was studied. Cattle were vaccinated with whole cells, disrupted cells and pili fractions of three strains of Moraxella bovis. Mice were vaccinated with pili fractions of three strains. The resistance of all vaccinated animals was challenged with virulent cultures of M. bovis. In an attempt to correlate the response seen after vaccination and challenge with a pili fraction of M. bovis, vaccinated cattle and mice were grouped on the basis of signs of disease manifested and compared on the basis of serological responses. Serum samples were tested for antibodies by a gel diffusion precipitin test. A greater number of the sera of resistant cattle had antibodies to the homologous pili antigen than those of vaccinated nonresistant cattle. Cattle vaccinated with disrupted cells were not resistant to infectious bovine kerato-conjuctivitis and their sera lacked antibodies against the pili antigens. Vaccinated mice were more resistant to infectious bovine kerato-conjuctivitis and their sera lacked antibodies against the pili antigens. Vaccinated mice were more resistant to challenge exposure by homologous than heterologous cultures. A greater number of the sera of resistant mice had antibodies to pili antigens than nonresistant mice.

Animals↗
PubMed1976

Experimentally induced infectious bovine keratoconjunctivitis: resistance of vaccinated cattle to homologous and heterologous strains of Moraxella bovis.

In studies to determine whether vaccination with one strain of Moraxella bovis would protect against challenge with virulent homologous or heterologous strains, calves were intramuscularly inoculated 3 times with formalin-killed M bovis, with 14 days between inoculations. Fourteen days after the 3rd vaccinal dose was given, all calves were exposed to homologous or heterologous virulent cultures of M bovis. The results indicated that vaccination with one strain of M bovis may induce protective immunity against homologous and heterologous challenge exposure; however, because vaccinated cattle resisted infection and disease produced by a homologous strain to a greater extent than they resisted those produced by heterologous strains, polyvalent vaccines or highly immunogenic common antigens may be needed to protect cattle against the numerous strains they might encounter under natural field conditions. There was minimal correlation between the presence of precipitating antibodies against the heterologous strains and the establishment of infection and disease.

Animals↗
PubMed1976

Infectious bovine keratoconjunctivitis: experimental induction of infection in calves with mycoplasmas and Moraxella bovis.

Eyes of 14 calves were exposed by conjunctival instillation to cultures of either Mycoplasma conjunctivae (6 calves) or Acholeplasma laidlawii (8 calves). Calves were observed for clinical signs of infectious bovine keratoconjunctivitis (IBK), and eyes were examined for the test organisms by bacteriologic cultural technique for 60 days. Acholeplasma laidlawii became established in the eyes of 5 of 8 calves; M conjunctivae became established in the eyes of 4 of 6 calves. On day 28, eyes of 9 of the 14 calves were exposed by conjunctival instillation to Moraxella bovis, and all developed IBK. Five calves exposed to Moraxenjunctivae or A laidlawii, but not to Mor bovis, did not develop IBK. Four calves not exposed to M conjunctivae or A laidlawii, but exposed to Mor bovis, developed IBK. Mycoplasmas do not have a major role in IBK, but might produce ancillary effects similar to those of infectious bovine rhinotracheitis virus, wind, ultraviolet radiation, dust, and other irritants.

Acholeplasma laidlawii↗
PubMed1976

Effects of vaccination with a Moraxella bovis bacterin on the subsequent development of signs of corneal disease and infection with M bovis in calves under natural environmental conditions.

A vaccination study was conducted for infectious bovine keratoconjunctivitis (IBK) in 440 purebred Hereford cattle (cows and their newborn calves) of the USDA Meat Animal Research Center cattle herd at Clay Center, Ne. The cattle were allotted to 4 groups: 60 calves were vaccinated with an autogenous Moraxella bovis bacterin (group 1); 60 calves that were matched with group 1 calves were designated nonvaccinated matched controls (group 2); 99 calves were peer group nonvaccinated controls (group 3); and 219 cows, the dams of the calves, were nonvaccinated consorts (group 4). The infection rates in cattle groups 1, 2, 3, and 4 during the summer were 96.6, 98.3, 100, and 79.1%, respectively, and the disease rates were 90, 93, 85, and 20%. The infection and the disease rates were significantly (P less than 0.01) different between claves and cows. The disease rate was also significantly different between older and younger cows. A larger percentage of the affected calves and cows had mild or moderate (61%) signs of IBK rather than severe (39%) signs. The rate of body weight gain was reduced in calves with severe signs of IBK. The results seemed to indicate that little would be gained by vaccinating cattle against IBK under the conditions of study.

Animals↗
PubMed1975

Bovine infectious keratoconjunctivitis: carrier state of Moraxella bovis and the development of preventive measures against disease.

Bovine infectious keratoconjunctivitis, which is caused by Moraxella bovis, occurs perennially in all cattle-raising areas. Disease may occur any time during the year but manifests itself often during summer when disease-enhancing factors such as ultraviolet radiation and fly population are increased. Although some recent research findings indicate that cattle can be immunized against the disease, many problems have to be overcome before the cattle industry can benefit from such immunization. Some pressing problems relate to lack of cross-protection between vaccines of different strains of M bovis, resistant or resilient carrier states, and how these factors affect vaccination regimens undertaken. Though cattle vaccinated with 1 strain are somewhat protected against subsequent challange by the same strain, protection against heterologous strains has not been demonstrated. In most herds, cattle harbor M bovis, and these carriers may serve as a source of infection.

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