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Biomedical subjects

H W Yoder

Publications and source records attributed to H W Yoder.

At least 19 recordsLinked to original sources
PubMed1988

Serological monitoring of eastern wild turkeys for antibodies to Mycoplasma spp. and avian influenza viruses.

From 1981 through 1986, plasma or serum samples were obtained from 322 wild turkeys (Meleagris gallopavo) from Georgia (n = 111), Kentucky (n = 21), Louisiana (n = 22), North Carolina (n = 118), Tennessee (n = 19), Missouri (n = 24) and Iowa (n = 7). These samples were tested for antibodies to Mycoplasma gallisepticum (MG) and in most instances, M. synoviae (MS), M. meleagridis (MM), and avian influenza (AI) virus. All 322 turkeys were seronegative for MG by the rapid plate agglutination (RPA) test. All of a subsample (n = 147) also were negative (titer less than or equal to 1:40) for MG by the hemagglutination inhibition (HI) test. Five of 253 turkeys (2%) were seropositive (+4 reaction) for MS by the RPA test; however, HI tests for MS on these five turkeys were negative as were attempts to isolate MS from trachea and homogenized lung tissue. Three of 253 turkeys (1%) were seropositive (+1 to +3 reactions) for MM by the RPA test. None of 210 turkeys had antibodies to AI by the agar gel precipitation test. These data suggest that populations of native eastern wild turkeys are not important in the epizootiology of MG, MS, MM, or AI.

Animals↗
PubMedDate not supplied

Influence of environment on airsacculitis: effects of relative humidity and air temperature on broilers infected with Mycoplasma synoviae and infectious bronchitis.

Mycoplasma synoviae (MS) obtained from broiler chickens condemned for airsacculitis was used to determine the influence of air temperature and relative humidity on the severity of airsacculitis produced experimentally. Infectious bronchitis virus was administered to 3-week-old broilers 5 days before aerosol exposure to MS broth cultures, producing extensive airsacculitis within 21-day study periods. High (31-32 C), medium (19-24 C), and low (7-10 C) air temperatures were studied in conjection with high (75-90%), medium (38-56%), and low (23-26%) relative humidities. Airsacculitis was most extensive (45%) at low temperatures regradless of high or medium humidity. The incidence of airsacculitis was greater (39%) at low humidity than at high humidity (17%) when air temperatures were medium. At high temperature, the trend was toward more airsacculitis (12%) at high humidity than (5%) at low humidity. However, the effect of cold air temperature was more dominant than the effect of relative humidity.

Aerosols↗
PubMedDate not supplied

Preparation of inactivated oil-emulsion vaccines with avian viral or Mycoplasma antigens.

The influence of the composition of water-in-oil emulsions on their physical characteristics was determined by preparing experimental emulsions with various water-to-oil ratios and various emulsifiers. Emulsions containing Tween 80 in the aqueous phase and Arlacel A or Arlacel 80 in the oil phase were lower in viscosity than emulsions containing only an oil-phase emulsifier. Viscosity decreased as the concentration of oil increased. Oil-emulsion vaccines prepared with aqueous- and oil-phase emulsifiers had low viscosity, were stable for more than 12 weeks at 37 C, and induced a marked primary antibody response in chickens.

Animals↗
PubMedDate not supplied

Nonspecific reactions to Mycoplasma serum plate antigens induced by inactivated poultry disease vaccines.

Nonspecific serum plate agglutination reactions to some avian mycoplasma antigens were induced by injecting chickens with several commercial poultry disease vaccines. All of the vaccines were inactivated, and most of them had oil-emulsion adjuvants. The serum plate agglutination reactions appeared within 2 to 3 weeks post-vaccination and generally persisted for several weeks. The plate test reactions were noted with both Mycoplasma gallisepticum (MG) and M. synoviae (MS) antigens, although the degree and duration of the reactions varied with the vaccine involved and the source of MG and MS plate test antigens. Attempts to prevent the nonspecific reactions by heat-inactivation at 56 C for 30 minutes or by addition of equal volumes of solutions of 2-mercaptoethanol, dithiothreitol, or 3 M sodium chloride were ineffective. No hemagglutination-inhibition activity against MG or MS antigens was induced by the vaccines.

Agglutination Tests↗
PubMedDate not supplied

Pathogenicity of Escherichia coli in aerosols for young chickens.

The relative pathogenicity of Esherichia coli isolates from poultry was determined by aerosol exposure of young chickens. Evidence of colisepticemia with airsacculitis and/or pericarditis and perihepatitis was evaluated. A system was devised that included the intratracheal (IT) inoculation of strain SE-17 infectious bronchitis virus (IBV) of chicks at 7 days of age followed by their aerosol exposure to E. coli culture suspensions 2 days later. Each experiment was terminated 6 days later. For comparative purposes in some studies, chicks were housed at 17 C and others at 27 C. The IBV-E. coli challenge procedure proved to be an effective way to determine the relative ability of E. coli isolates to cause death and/or gross lesions in young chickens. With some E. coli isolates, there were minimal or no obvious adverse effects from exposure except when chickens were previously inoculated with IBV. When chicks were housed at 17 C instead of 27 C, slight increases in mortality and decreases in gross lesions were generally observed, probably because the earlier deaths did not allow time for the lesions to become as evident. The E. coli isolate #18344 (Congo Red-positive) was consistently more pathogenic than the Congo Red-negative version of that isolate. Cultures of E. coli previously demonstrated to be pathogenic (VA O1:K1 and DL #29) were among the most pathogenic isolates evaluated in these experiments and were similar to the Congo Red-positive #18344 isolate.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMedDate not supplied

Recent advances in filtered-air positive-pressure (FAPP) housing for the production of disease-free chickens.

Design and performance information on a filtered-air positive-pressure (FAPP) housing system for disease-free poultry flocks is presented. The system includes many special features that result in excellent biological security, easy cleanup and maintenance, efficient control of environment, and a centralized alarm in the event of problems. The system has now housed eight flocks without any major problems. Based on its performance thus far, it should be useful as a reliable housing system for disease-free poultry.

Animal Husbandry↗
PubMedDate not supplied

Congo red binding by Escherichia coli isolates from chickens.

An attempt was made to use a recently reported special Congo red medium to determine the pathogenicity of Escherichia coli isolates obtained from chickens. The inclusion of bile salts in the Congo red medium as described in previous reports by others was found in the current experiments to cause the production of red colonies from almost all E. coli cultures tested, including known Congo red-negative control cultures. Cultures of E. coli, regardless of their pathogenic history, rarely produced red colonies on the Congo red medium without added bile salts. Numerous isolates of other bacterial genera were examined and found to produce red colonies on the Congo red medium with or without added bile salts.

Animals↗
PubMedDate not supplied

Efficacy of experimental inactivated mycoplasma gallisepticum oil-emulsion bacterin in egg-layer chickens.

Six groups of white leghorn pullets were studied to determine the ability of beta-propiolactone-inactivated Mycoplasma gallisepticum (MG) oil-emulsion bacterins to counteract reductions in egg production caused by MG infection. The pullets were inoculated with 0.5 ml of MG bacterin subcutaneously in the neck at about 20 weeks of age and were challenged with MG near 28 weeks of age, when they were in peak egg production. Various challenge schemes with infectious bronchitis virus were used at the time of MG challenge to increase the reduction in egg production. MG bacterins afforded protection against moderate drops in egg production in at least three of the studies, where the unvaccinated challenged control hens exhibited reduced egg production.

Animals↗