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  • Author or Editor: W. L. Steffens x
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SUMMARY

Adult umbrella cockatoos, Moluccan cockatoos, African grey parrots, and a yellow-headed Amazon parrot were inoculated im or sc with β-propiolactone-treated psittacine beak and feather disease (pbfd) virus. Thirty- to 45-day-old African grey parrot, umbrella cockatoo, and sulphur-crested cockatoo chicks also were vaccinated with the same inoculum. The hemagglutination inhibition (hi) and agar-gel diffusion tests were used to assay for post-vaccination development of anti-pbfd virus antibodies. All adult vaccinates seroconverted and had increases in hi and precipitating antibodies. The vaccinated chicks had increased concentrations of hi antibodies, but precipitating antibodies could not be detected. To demonstrate that chicks from vaccinated hens are protected from pbfd virus challenge, 3 African grey parrot chicks and 2 umbrella cockatoo chicks from vaccinated hens and 1 African grey parrot chick and 1 umbrella cockatoo chick from nonvaccinated hens were exposed to purified pbfd virus. Chicks from the vaccinated hens remained clinically normal during the 50-day test period. Chicks from the nonvaccinated hens developed clinical and histologic lesions of pbfd. Infected tissues from these birds were confirmed to contain viral antigen, using immunohistochemical staining techniques. The pbfd virus was recovered from the affected birds. These findings indicate that adult and 30- to 45-day-old psittacine birds will seroconvert following vaccination with β-propiolactone-treated pbfd virus. Also, hens inoculated with β-propiolactone-treated pbfd virus produce chicks that are, at least temporarily, resistant to virus challenge.

Free access
in American Journal of Veterinary Research

SUMMARY

Conditions for psittacine beak and feather disease (pbfd) virus hemagglutination and hemagglutination-inhibition (hi) test reactions are defined. The pbfd virus was found to hemagglutinate cockatoo and some guinea pig erythrocytes. The hi test was used to assay serum antibody titer in birds with active pbfd virus infections and in others that had been exposed to diseased birds. On the basis of hi antibody titers in psittacine birds that had been exposed to pbfd virus, but remained clinically normal, we suggest that some birds exposed to the virus are able to mount an effective immune response. Birds with active pbfd virus infections had lower antibody values than did birds that had been exposed to the virus, but remained clinically normal. On the basis of these findings, the ability to develop a suitable hi antibody response may be crucial in determining the disease status of susceptible birds exposed to the pbfd virus. If hi antibodies are found to have neutralizing activity, then the fact that a high hi titer was induced in birds inoculated with purified pbfd virus might suggest that an immunization program would be effective in preventing pbfd virus infections.

Free access
in American Journal of Veterinary Research

SUMMARY

Psittacine beak and feather disease (pbfd) virus was recovered from the feces and crop washings from various species of psittacine birds diagnosed with pbfd. High concentrations of the virus also could be demonstrated in feather dust collection from a room where 22 birds with active cases of pbfd were being housed. The virions recovered from the feces, crop, and feather dust were confirmed to be pbfd virus by ultrastructural, physical, or antigenic characteristics. Virus recovered from the feather dust and feces hemagglutinated cockatoo erythrocytes. The specificity of the agglutination was confirmed by hemagglutination inhibition, using rabbit antibodies against pbfd virus. During the test period, 26% (8 of 31) of the birds screened were found to be excreting pbfd virus in their feces, and 21% (3 of 14) of crop washings were positive for pbfd virus. Some birds in the sample group had active cases of diarrhea, whereas others had normal-appearing feces. Diarrhea was found to be the only significant indicator of whether a bird was likely to be excreting virus from the digestive tract. These findings suggest that exposure of susceptible birds to pbfd virus may occur from contact with contaminated feather dust, feces, or crop secretions. Viral particles that were morphologically similar to parvovirus (20- to 24 nm-icosahedral nonenveloped virions) also were recovered from feces of some of the birds.

Free access
in American Journal of Veterinary Research

Summary

A virulent field isolate and 2 vaccine strains of Pasteurella multocida A:3,4 were compared for resistance to phagocytosis by turkey macrophages and heterophils, using in vitro assays. The least virulent vaccine strain (M-9) was phagocytosed to a greater degree than was the field isolate or the other vaccine strain (Clemson University). All 3 bacteria differed significantly from each other in the amount of capsular material present as measured by polycationic ferritin labeling and electron microscopy. Removal of the capsule with hyaluronidase resulted in a significant increase in phagocytosis of the field isolate.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the prevalence of bovine viral diarrhea virus (BVDV)–infected alpaca herds in the United States and investigate factors associated with seropositive herd status and, subsequently, determine the proportion of animals within seropositive alpaca herds that are persistently infected (PI) carriers for BVDV, obtain information regarding previous herd exposure to BVDV, determine titers of anti-BVDV antibodies of dams, and ascertain whether individual seropositive crias had received supplemental colostrum at birth.

Design—Prevalence study.

Animals—63 alpaca herds with ≥ 12 registered female alpacas.

Procedures—250 alpaca breeders were randomly selected from 562 eligible herds listed in the Alpaca Owner and Breeders Association membership directory and mailed a voluntary participation request. Sixty-three alpaca breeders participated in the study. From each herd, blood samples from ≥ 4 crias were tested for BVDV, BVDV RNA, and serum neutralizing antibodies against BVDV. A region of the genome of BVDV recovered from PI crias was sequenced to determine genetic homology.

Results—Among the 63 herds, 16 (25.4%) had seropositive crias and 4 (6.3%) had PI crias. Infections in 3 of the 4 herds with PI crias were linked as evidence by the genetic homologies of viruses. In addition to PI crias, feeding supplemental colostrum was associated with herd seropositivity.

Conclusions and Clinical Relevance—Results confirmed the importance of BVDV infections in alpacas in the United States and highlighted the importance of determining the BVDV infection status of animals before they are commingled to limit exposure of herds to BVDV infection.

Full access
in Journal of the American Veterinary Medical Association