Harry W. Yoder

Avian infectious bronchitis--virus distribution in tissues of chicks.

The virus of infectious bronchitis (IB) multiplies primarily in the respiratory tract; little is known about its presence in other organs. Fabricant and Levine (1) reported the presence of virus in eggs during active infection and for 36 days thereafter. Winterfield and Hitchner (5) isolated IB virus from kidneys. The main purpose of this study was to determine what tissues were invaded by IB virus of low and high embryo-passage levels, to estimate the concentration of virus in the tissues, and to determine whether different serological types of avian bronchitis virus would yield similar results.

A historical account of the diagnosis and characterization of strains of Mycoplasma gallisepticum of low virulence.

Numerous chicken flocks were studied beginning in 1970 because of questionable results on their serologic tests for Mycoplasma gallisepticum (MG). Typically a low number of hens in the flocks were positive reactors to the rapid serum plate test and rarely had hemagglutination-inhibition (HI) titers over 1:80. Usually no clinical signs were observed. Isolates of MG eventually were cultured from most of the flocks that exhibited that type of marginal serologic pattern. In the laboratory, the MG isolates were frequently less virulent and less pathogenic than the typical field isolates recovered in previous years. Most isolates produced airsacculitis of varying severity when broilers were exposed to the MG cultures as aerosols following exposure to infectious bronchitis virus. They became positive on the rapid serum plate test and developed moderate to high HI titers. Egg-transmission appeared to be the most likely means of transmission, even though the infected progeny rarely showed clinical signs of disease.

Preparation of Mycoplasma synoviae hemagglutinating antigen and its use in the hemagglutination-inhibition test.

SUMMARY A satisfactory hemagglutinating (HA) antigen was produced from isolate WVU 1853 of M. synoviae grown in a mycoplasma broth formulated by Frey. The HA antigen, employed in the HI test, showed good specificity in differentiating M. synoviae from M. gallisepticum infection. There was no drop in HA titer when the antigen was stored at -65 C for 4 months. When the antigen was stored at -13 C or higher, the drop in HA titer increased as the length of time in storage increased. When 4 units of antigen were used per tube in the HI test, the HI results closely agreed with those of the original antigen stored at -65 C, which had no loss in HA titer.

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.

Serologic Response of Chickens Vaccinated With Inactivated Preparations of Mycoplasma gallisepticum

SUMMARY Several lots of inactivated Mycoplasma gallisepticum (MG) vaccine were prepared from 1% suspensions of the R strain. Portions were inactivated with 0.1% beta-propiolactone at room temperature (24 C) for 3 hours, and other portions were agitated with 0.5% formalin at 37 C for 3 hours. Part of each lot was then further processed to provide oil-emulsion preparations with various ratios of aqueous phase to oil phase. Tween 80 was added to the aqueous phase of most vaccines, and Arlacel 80 was added to the oil phase before final blending. The resulting hemagglutination-inhibition (HI) titers decreased in magnitude and duration in the following order: aqueous phase to oil phase ratios of 1:2, 1:4, and 1:1 followed by 25% aluminum hydroxide and aqueous vaccines. There was little difference in HI response of young broiler and egg-laying-type chickens injected by either the intra-foot-pad or subcutaneous routes with 0.5-ml doses of vaccines inactivated by either formalin or beta-propiolactone. Less than 0.25 ml was inadequate, and more than 0.5 ml was not greatly better. Two doses 8 weeks apart produced higher HI titers over a longer period than did a single dose. All of the water-in-oil vaccine emulsions were stable for at least 60 days at 37 C. No visible tissue reactions were produced by any of the vaccines studied.

Preincubation heat treatment of chicken hatching eggs to inactivate mycoplasma.

Eggs from chickens experimentally infected with Mycoplasma gallisepticum were heated for 11-15 hr in an incubator containing approximately 2,000 medium-sized eggs and were removed for normal incubation once they reached internal temperatures of 110117 F. After 14 days of normal incubation, all heated and control infected eggs were cultured for M. gallisepticum. Normal control eggs were employed with each heating run to determine hatchability. It was concluded that M. gallisepticum could be inactivated when infected hatching eggs reached an internal temperature of 114 F within 12-14 hr if the eggs were started at room temperature (78 F) and the incubator heater was on constantly with no thermostat control. Hatchability was usually reduced approximately 8-12%o. Results were similar with M. synoviae except that a slightly higher temperature was necessary. It is suggested that just reaching an internal egg temperature of 114.5 F during a 12-to-14-hour preincubation heating period without thermostat control should inactivate M. gallisepticum and M. synoviae in infected chicken hatching eggs.

Identification of avian mycoplasma isolates by the agar-gel precipitin test.

Recent isolates of Mycoplasma gallisepticum and Mycoplasma synoviae were readily typed by the agar-gel precipitin test with antigens prepared by freezing and thawing, sonic vibration, or sodium dodecyl sulfate. Specific antisera prepared in rabbits or in foot-pad-inoculated chickens were adequate for culture typing. Relatively few sera from chickens and turkeys in naturally infected flocks reacted positively. The precipitin reaction was highly specific, however.

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)

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.

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.