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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

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

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

Objective

To determine safety, immunogenicity, and efficacy of an inactivated avian polyomavirus vaccine in nonbudgerigar psittacine birds that varied in age, species, and immunologic status.

Animals

Safety of the vaccine was evaluated in 1,823 psittacines representing more than 80 species. Immunogenicity was evaluated in 285 birds (260 of various Psittaciformes species, 25 chickens). Efficacy was evaluated in 104 birds (78 of various Psittaciformes species, 26 chickens).

Procedures

Safety was evaluated by vaccinating birds that were determined to be seronegative or seropositive (titer > 1:10) prior to vaccination. Birds were then evaluated for clinically detectable systemic or local reactions for 2 months to 2 years. Immunogenicity was evaluated by testing for virus-neutralizing antibodies, vaccinating each bird twice, and then testing for a significant change in antibody titer. Efficacy was evaluated by vaccinating birds, followed in 2 to 4 weeks by intramuscular or intravenous challenge exposure. After challenge exposure, protection was evaluated by attempting to recover virus from tissues or by observing birds for clinical signs of disease and testing for a significant change in titer.

Conclusions

Avian polyomavirus vaccine is safe, immunogenic, and efficacious for use in multiple species of mature and immature psittacines.

Clinical Relevance

Until now, prevention of polyomavirus infection in psittacine birds could only be accomplished through strict isolation to reduce potential exposure to the virus. The USDA-registered inactivated avian polyomavirus vaccine can safely be used to protect vaccinates from infection and control spread of this virus in flocks. (Am J Vet Res 1998,59:143–148)

Free access
in American Journal of Veterinary Research