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C W Beard

Publications and source records attributed to C W Beard.

67 records · Page 4Linked to original sources
PubMedDate not supplied

A comparison of Newcastle disease hemagglutination-inhibition test results from diagnostic laboratories in the southeastern United States.

A two-phase comparison was conducted using the Newcastle disease hemagglutination-inhibition (HI) test to determine the variation of serologic results from poultry diagnostic laboratories in the southeastern United States. In the first phase of the comparison, most of the 17 participating laboratories in 10 states found the coded negative sera to be negative, and most found the potent sera to have the highest titers. However, there was a wide range of geometric mean titers (GMT's), from 2 to greater than or equal to 113 for the same serum samples. Each laboratory was strikingly consistent at reporting unknown but identical triplicate serum samples to have the same titer, even though the titers were frequently quite different from those of other laboratories. This observation indicated that currently used procedures yielded good reproducibility within individual laboratories but not necessarily between laboratories. In the second phase of the comparison, participants were furnished another set of coded sera, antigen, and a suggested incubation time. The implementation of the recommended incubation period reduced the extent of the lab-to-lab differences, but GMT's between labs still ranged from 11 to 95 on identical serum samples. When all laboratories used the same antigen, the average of the GMT results increased from 38 to 48, but the GMT's from the different laboratories ranged from 7 to more than 2048. Although the comparison exercise resulted in some improvement in uniformity, it was obvious that a continuing voluntary program should be initiated to certify laboratories and promote uniform test methods for specific serologic procedures using coded sera.

Animals↗
PubMedDate not supplied

Use of the Nobuto blood-sampling paper strip for Newcastle disease serology.

Dried whole blood collected by the paper-strip method of Dr. Kenzo Nobuto was evaluated for use in the Newcastle disease hemagglutination-inhibition (HI) test. When dried blood on the Nobuto strip was eluted in 1.0 ml of diluent, the resulting HI titers were similar to titers obtained with sera diluted 1:10. Both storage time and temperature influenced the stability of HI activity in dried blood, though the influence was minimal and is considered to have little significance in diagnostic serology, The advantages of this method of blood collection for Newcastle disease HI tests are discussed.

Animals↗
PubMedDate not supplied

Experimental infection of laying chickens with adenovirus 127 and with a related virus isolated from ducks.

Infection of commercially reared white leghorn and white rock hens with adenovirus 127 was associated with decreases in total egg production, external egg quality, egg weight (P less than 0.01), and eggshell thickness (P less than 0.01). The egg-production and egg-quality disturbances were transient, and production returned to normal approximately 4 weeks postinfection. Infection of white leghorns with a hemagglutinating adenovirus isolated from Missouri ducks did not adversely affect egg production, external egg quality, or eggshell thickness, but it was associated with decreased egg weight (P less than 0.01). Prior infection with the duck adenovirus prevented the adverse egg-production effects of adenovirus 127 infection. Mean hemagglutination-inhibition antibody titers of chickens infected with adenovirus 127 or with duck adenovirus ranged from 1:588 to 1:10809, and mean titers of uninfected chickens did not exceed 1:2.

Adenoviridae Infections↗
PubMedDate not supplied

Influence of formulation on the efficacy of experimental oil-emulsion Newcastle disease vaccines.

Twenty-one experimental oil-emulsion vaccines with different emulsifier contents, aqueous-to-oil ratios, and antigen concentrations were compared by immunization of 4-week-old chickens. Vaccines that contained oil-phase (Arlacel 80) and aqueous-phase (Tween 80) emulsifiers induced 2-to-4-fold higher hemagglutination-inhibition titers than vaccines with only the oil-phase emulsifier. The emulsion vaccines containing both emulsifiers were also more stable at 37 C and less viscous than those containing only the oil-phase emulsifier. Vaccines that had different aqueous-to-oil ratios and contained different quantities of allantoic-fluid antigen (1.2% to 50% of the vaccine volume) induced similar protection against challenge, but hemagglutination-inhibition titers were proportional to the amount of antigen added. Vaccines that had different aqueous-to-oil ratios but contained equal amounts of antigen induced similar hemagglutination-inhibition titers and similar protection against challenge.

Animals↗
PubMedDate not supplied

Atypical disease produced in chickens by Newcastle disease virus isolated from exotic birds.

Chickens were infected with a Newcastle disease virus (NDV) recovered from exotic birds with severe clinical disease and with lesions characteristic of viscerotropic velogenic Newcastle disease (VVND). The infection in chickens was inconsistently lethal, some infected chickens were not clinically affected, and gastrointestinal involvement was only marginally evident. Pathogenicity of the virus for chickens was not detectably altered by laboratory passage in chickens or by limit dilution passage in chicken embryos. The results suggest that the difference between velogenic NDV pathotypes may not always be distinct and that clinical manifestations of VVND in chickens may not always be predictable based on signs and lesions observed in exotic birds.

Age Factors↗
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The susceptibility of chicks to Salmonella montevideo in artificially contaminated poultry feed.

Feed artificially contaminated with various levels of nalidixic-acid-resistant Salmonella montevideo was fed to newly hatched chicks for 7 days. Cloacal and cecal swabs were obtained from the chicks at 7, 14, and 21 days of age to monitor Salmonella colonization relative to the feed contamination level. In one of three trials, less than one Salmonella montevideo per gram of feed was sufficient to establish colonization in 1-to-7-day-old chicks.

Animal Feed↗
PubMedDate not supplied

The influence of test conditions on Newcastle disease hemagglutination-inhibition titers.

Replicate samples of serum from chickens immune to Newcastle disease were titrated to determine the influence of certain test conditions on hemagglutination-inhibition (hi) titers. The test conditions studied were those most likely to vary in normal laboratory operations. The most marked effect on magnitude of HI titers was incubation time of twofold serum dilutions in antigen-saline; the average titer increase after incubation of the serum-antigen mixture for 1 hr at 37 C was log2 2.3 (fivefold). Twofold increases in virus concentration of the antigen-saline diluent caused an average titer reduction of log2 0.8. Shifts in HI titers were only minor with twofold changes in erythrocyte concentration (log2 0.3), with variations of test reading times from 0.5 to 2.0 hr (log2 0.1), and with variations in the period between preparation of the initial 1:10 serum dilution in antigen-saline and the subsequent serum dilutions (log2 0.3).

Animals↗
PubMedDate not supplied

Comparison of three experimental inactivated oil-emulsion Newcastle disease vaccines.

White Leghorn pullets vaccinated previously with live Newcastle disease virus (NDV) were revaccinated at point-of-lay with 3 experimental oil-emulsion (OE) Newcastle disease vaccines to determine whether immunogenicity of OE vaccines is influenced by emulsion composition differences. The vaccines used were formulated differently but contained equal amounts of inactivated NDV in stable, low-viscosity, water-in-oil emulsions. Serological responses to the vaccines differed (P less than 0.01), but 55 of 56 OE vaccinates remained clinically normal following challenge exposure with viscerotropic velogenic NDV 28 or 44 weeks after revaccination; 4 of 21 nonrevaccinated controls and all of 20 nonvaccinated challenge controls were clinically affected or died.

Animals↗
PubMedDate not supplied

Embryonated eggs compared with fragments of chorioallantois attached to egg shell for isolation of Newcastle disease virus.

The feasibility of using fragments of chorioallantois attached to egg shell (C-S) as an alternative to embryonated eggs for isolating Newcastle disease virus (NDV) was assessed. In paired titrations of 6 strains of virus, embryonated eggs detected an average of 6-to-7-fold greater amounts of virus than did C-S fragments. The efficiency of isolation of viscerotropic velogenic NDV from 240 swab samples was 97% in embryonated eggs and 84% in C-S fragments. Sensitivity differences between the 2 host systems were revealed only in tests of samples expected to contain small amounts of virus. These results suggest that C-S fragments can be reliably used in some but not all instances, thereby relieving logistic constraints sometimes associated with the use of embryonated eggs.

Allantois↗
PubMedDate not supplied

Comparative efficacy of the B-1 and VG/GA vaccine strains against velogenic viscerotropic Newcastle disease virus in chickens.

Groups of eight 1-day-old white rock chickens were vaccinated with either B-1 or VG/GA strain of Newcastle disease virus (NDV) by eyedrop instillation. Some of the chickens were vaccinated a second time at 17 days of age. Eight groups of chickens vaccinated either once or twice were challenged with the California 1083 strain of velogenic viscerotropic Newcastle disease virus (VVNDV) at 30 days of age by either intramuscular injection or eyedrop instillation. One group of unvaccinated control chickens was challenged by eyedrop instillation. All eight unvaccinated controls, two of the 16 B-1 vaccinates, and none of the 16 VG/GA vaccinates died following challenge. There were no obvious differences in pre-challenge serum antibody levels among the vaccinates. Only the twice-vaccinated chickens that were challenged by eyedrop and the unchallenged vaccinates failed to show a marked rise in serum antibody titers. The VG/GA strain of NDV provided protection against the mortality associated with VVNDV challenge similar to that provided by the B-1 strain within the conditions of this experiment.

Animals↗