The influence of inhalation of carbon dioxide on chickens, including resistance to infection with Newcastle disease virus.
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Aerosols↗
Biomedical subjects
C W Beard
Publications and source records attributed to C W Beard.
Aerosol transmission of hog cholera.
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Aerosols↗
Efficacy of vaccines in chickens against highly pathogenic Hong Kong H5N1 avian influenza.
In 1997, highly pathogenic (HP) H5N1 avian influenza virus (AIV) caused infections in poultry in Hong Kong and crossed into humans, resulting in a limited number of infections including 18 hospitalized cases and six associated deaths. The unique ability of this, AIV to infect both poultry and people raised a concern for the potential of humans to be biological as well as mechanical vectors of this AIV to poultry. The current study was undertaken to determine if existing vaccines and their technologies could be used during an outbreak to protect poultry. Commercial and experimental inactivated whole H5 AIV and baculovirus-expressed AIV H5 hemagglurinin protein vaccines provided protection from clinical signs and death in chickens after lethal challenge by human-origin HP H5N1 Hong Kong strains 156/97 and 483/97. The commercial and experimental inactivated vaccines had mean protective doses ranging from 0.25 to 0.89, which represents the milligrams of viral protein in the vaccines that provided protection from death in half of the birds. Furthermore, the vaccines reduced the ability of the challenge AIV to replicate in chickens and decreased the recovery of challenge AIV from the enteric and respiratory tracts, but the use of a vaccine will nor totally prevent AI virus replication and shedding. Existing vaccines will protect poultry from mortality and reduce virus replication from the new HP AIV strain that can infect both poultry and humans.
Animals↗
Preparation of Newcastle disease virus hemagglutination-inhibition test antigen.
A method of preparing antigen for Newcastle hemagglutination-inhibition (HI) tests is described; polyethylene glycol precipitation is used for the virus concentration. The virus was inactivated with either formalin or beta-propiolactone. Glycerin was used to stabilize the hemagglutinin activity of the antigen. The stability, uninfectivity, and slow eluting features of the antigen should aid in obtaining accurate HI results without the risks inherent in the use of live virus.
Animals↗
Effect of route of administration on the efficacy of a recombinant fowlpox virus against H5N2 avian influenza.
A recombinant fowlpox vaccine virus containing the H5 hemagglutinin gene of avian influenza virus was administered to susceptible chickens via wing-web puncture, eye drop, instillation into the nares, and drinking water. Even though there was a negligible hemagglutination-inhibition (HI) serologic response, all 10 chickens vaccinated by wing-web puncture remained without obvious signs of disease and survived challenge with a highly pathogenic strain of H5N2 avian influenza virus. All unvaccinated chickens and those vaccinated by nasal and drinking-water routes died following challenge. Eight of 10 chickens vaccinated with the recombinant by eyedrop died. All vaccinates were negative on the agar gel precipitin (AGP) test, and only one chicken had a positive HI titer before challenge. All chickens that survived challenge had high levels of HI antibody and were positive on the AGP test, indicating that they were infected by the challenge virus.
Animals↗
A feather-trap system for the removal of chicken feathers from laboratory sewage.
A simple feather-trap system is described for use on the drain lines of buildings housing poultry for research or other purposes where floors are frequently washed. The trap uses disposable plastic-mesh bags that can efficiently remove almost all feathers from the water, preventing sewer lines from being blocked by compacted feathers. Critical measurements and operational procedures are described.
Animals↗
Evaluation of the efficacy of an oil-emulsion bacterin for protecting chickens against Salmonella enteritidis.
To assess the potential protective efficacy of a Salmonella enteritidis bacterin, an acetone-killed oil-emulsion vaccine was prepared from a phage type 13a S. enteritidis strain and administered subcutaneously to hens in two experiments. Hens were housed individually, and every other hen was vaccinated (at 23 weeks of age in one experiment and at 45 weeks in the other). A second (booster) bacterin injection was administered 6 weeks later in both experiments. Three weeks after the second vaccination, all hens were challenged with an oral dose of approximately 10(9) cells of a heterologous (phage type 14b) S. enteritidis strain. In both trials, S. enteritidis was isolated from fewer internal organs (spleens, ovaries, and oviducts) and pools of egg contents from vaccinated hens than from unvaccinated control hens. Vaccination did not, however, affect the percentage of hens that shed S. enteritidis in feces in either experiment.
Animals↗
Protection of chickens against highly pathogenic avian influenza virus (H5N2) by recombinant fowlpox viruses.
Two recombinant fowlpox viruses containing the avian influenza H5 hemaglutinin (HA) gene were evaluated for their ability to protect chickens against challenge with a highly pathogenic isolate of avian influenza virus (H5N2). Susceptible chickens were vaccinated with the parent fowlpox vaccine virus or recombinant viruses either by wing-web puncture or comb scarification. Following challenge 4 weeks later with highly pathogenic avian influenza virus, all birds vaccinated by the wing-web method were protected by both recombinants, while 50% and 70% mortality occurred in the two groups of birds vaccinated by comb scarification. Birds vaccinated with the unaltered parent fowlpox vaccine virus or unvaccinated controls experienced 90% and 100% mortality, respectively, following challenge. Hemagglutination-inhibition (HI) antibody levels were low, and agar-gel precipitin results were negative before challenge. Very high HI titers and positive precipitating antibody responses were observed in all survivors following challenge.
Animals↗
Amantadine resistance among hemagglutinin subtype 5 strains of avian influenza virus.
Several avian influenza virus strains of hemagglutinin subtype 5 were assayed for sensitivity to the antiviral drug amantadine. Most strains exhibited little sensitivity to the drug as measured by plaque reduction. The A/Chicken/Scotland/59 (CS59), however, was highly sensitive, making it easily distinguishable from the other H5 strains. Drug sensitivity of the viruses was also assayed in chicken embryos. The in ovo patterns of amantadine sensitivity differed from those detected in cell culture. The CS59 isolate could not be distinguished from all the other strains on the basis of its response to amantadine in ovo. Although amantadine protected chickens inoculated with CS59 from morbidity and mortality, drug-resistant viruses were readily isolated from the infected birds. As found with other amantadine-resistant variants, the structure of the matrix gene was altered in the resistant isolates. These results demonstrate that amantadine resistance is widespread among avian influenza viruses of the H5 subtype, that drug sensitivity in cell culture does not necessarily reflect responses to amantadine in ovo and in vivo, and, as previously found, amantadine-resistant derivatives of H5 strains may be isolated from birds protected by the drug.
Amantadine↗
Serological detection of experimental Salmonella enteritidis infections in laying hens.
The antibody response of laying hens to experimental Salmonella enteritidis infection was evaluated in microagglutination, tube agglutination, and rapid whole-blood plate agglutination assays. Hens of three different ages were infected by either oral inoculation or horizontal contact transmission. Blood was collected at weekly intervals, and the presence of specific antibodies was assessed by reaction with antigens prepared from strains of S. enteritidis and S. pullorum. The sensitivity of detection of infected hens did not vary significantly between the assays, as all three tests effectively identified most exposed hens as seropositive. Within each test, however, variation was observed in the detection sensitivity when different antigens were used. The microagglutination titers of serum samples were determined by serial dilution. Antibody titers peaked at 1 to 2 weeks postinoculation and declined steadily, although most birds were still identified as seropositive at 10 weeks postinoculation. The mean microtest titers obtained with S. enteritidis antigens were higher than with an S. pullorum antigen, indicating greater test sensitivity. However, use of the S. pullorum antigen resulted in fewer false positives when sera from uninfected control hens were tested. The titers of contact-exposed hens peaked later and at lower values than did those of inoculated hens, but these two groups of hens had similar antibody titers after the third week postinoculation.
Agglutination Tests↗
Production of Salmonella enteritidis-contaminated eggs by experimentally infected hens.
Laying hens of three different ages were experimentally infected with a strain of Salmonella enteritidis by either oral inoculation or contact transmission. Total egg production was depressed in exposed hens of all three age groups. Persistent intestinal shedding was observed in a small number of hens. Eggs with contents contaminated by S. enteritidis were produced by exposed hens at a high frequency, but only during a fairly short period of time that extended through approximately 1 week postinoculation for older hens and through 2 weeks for younger hens. S. enteritidis was recovered from whole yolks and albumen of these eggs at similar frequencies, but not from the content of yolks. Eggs with contaminated shells were also produced, but at a lower frequency. Contaminated eggs were produced by orally inoculated and contact-exposed hens at similar frequencies. S. enteritidis was not isolated from the contents of eggs laid by hens infected with other S. enteritidis strains.
Animals↗
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↗
Isolation of Salmonella enteritidis from internal organs of experimentally infected hens.
Tissues from experimentally infected hens were examined for the presence of Salmonella enteritidis (SE). SE was recovered from internal organs of both orally inoculated hens and hens infected by horizontal contact transmission. SE was isolated from 58% of the ceca, 51% of the livers, 47% of the spleens, 17% of the ovaries, and 17% of the oviducts of hens sampled during the first 5 weeks after exposure. SE was recovered at a low frequency from all internal organs sampled for as long as 22 weeks after exposure.
Animals↗
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↗
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↗
Influence of environmental temperatures on the serologic responses of broiler chickens to inactivated and viable Newcastle disease vaccines.
Commercial and specific-pathogen-free (SPF) nonselected broilers were held at environmental temperatures that simulated the cyclic diurnal extremes for either hot (26.6 C-40.7 C) or moderate (18.3 C-32.3 C) summer temperatures. The chicks received either inactivated or viable La Sota Newcastle vaccines at various times after the initiation of the temperature extremes. When held at moderate temperatures for 7 days and then injected with inactivated vaccine, commercial chicks developed slightly higher but not statistically different levels of antibody compared with chicks held in the hot environment. In one experiment, the geometric mean serologic hemagglutination-inhibition responses of SPF chickens housed at extremely high temperatures for 4 days before being injected with inactivated vaccine were significantly greater (P less than or equal to 0.05) than those held at moderate temperatures. The reverse was apparent for chickens that received live vaccine virus after being in the hot environment for any of several lengths of time before vaccination.
Animals↗
Influence of dietary calcium stress on lethality of avian influenza viruses for laying chickens.
The effect of calcium stress was studied in an attempt to reproduce lethal infections in laying chickens with A/Chicken/Alabama/75 (H4N8) influenza virus and with two nonpathogenic H5N2 influenza viruses from the 1983-84 outbreak in the eastern United States. Hens were fed calcium-deficient or standard diets for 7 to 14 days; then the calcium-deficient feed was replaced with standard feed supplemented with ad libitum oyster shell, and both groups of hens were inoculated with virus. When hens were infected with the H4N8 virus, respective mortalities of those on the calcium-deficient and standard diets were 19% (27/141) and 5% (7/143). The H5N2 viruses did not kill hens fed either diet. In standard pathogenicity tests, Alabama H4N8 viruses reisolated from the hens that died generally were more lethal for 4-week-old chickens than the stock virus. These results argue for characterization of the Alabama H4N8 virus as pathogenic rather than nonpathogenic as originally determined.
Animals↗
Emergence of amantadine-resistant H5N2 avian influenza virus during a simulated layer flock treatment program.
An experiment was designed to simulate field conditions in which preventive treatment is not initiated until after some chickens in a flock are infected with avian influenza (AI). Twelve hens began to receive amantadine hydrochloride on the day they were inoculated (day 0) with highly pathogenic AI virus, A/chicken/Pa/1370/83. These hens remained clinically normal through 8 days postinoculation (PI), but five died after day 9; mean death time (MDT) was 18 days. Three of 12 hens given amantadine beginning 1 day PI died (MDT 5.4 days), seven of 12 hens given amantadine beginning 3 days PI died (MDT 3.7 days), and all 12 inoculated hens not given amantadine died (MDT 4.9 days). The delayed mortality in the day 0 treatment group was likely due not to the original inoculum but to the emergence of a drug-resistant virus population. Virus isolated from a dead hen from that group was resistant to the actions of amantadine in both in ovo and in vivo tests. The lack of late mortality due to the drug-resistant virus in the day 1 and day 3 treatment groups, which were in close contact with the day 0 treatment group, was attributed to their becoming infected before treatment with the drug and to the development of protective immunity.
Amantadine↗