Progress 10/01/19 to 09/30/20
Outputs Target Audience:Poultry health professionals Veterinarians University and Industry Ph.D. Scientists (Virology and Molecular Biology) International and domestic poultry producers International and domestic vaccine company R&D Scientists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?National and international presentations were given at scientific conferences in Bogota Columbia, Santiago Chile and the USDA Poultry Research Lab in Athens Georgia. These conferences were attended by a range of poultry professionals that included veterinarians, poultry health professionals, scientists, vaccine company representatives and poultry producers. How have the results been disseminated to communities of interest?In addition to the national and international invited presentations, the results were published in an abstract and poster session given at the 2020 American Association of Avian Pathologists virtual meeting. What do you plan to do during the next reporting period to accomplish the goals?Studies will continue on assessment of the antigenicity and pathogenicity of evolving IBDV strains from commercial broiler and layer flocks. Samples from backyard poultry flocks will be sought to determine the genetic relationship of those isolates to IBDV in commercial flocks.
Impacts What was accomplished under these goals?
The use of virus-like-particle (VLP) vaccinesto controlinfectious bursal disease is predicated on the identificaton of new strains of the infectious bursal disease virus (IBDV). Although antigenicity is the primary characteristic that needs to be identified, we also needto determine if the evolving IBDV strains are a pathogenic threat to the poultry industry. The bursa tissues from the 8 field outbreaks of infectious bursal disease were homogenized in an equal volume of PBS and then diluted 1:10 in PBS before inoculation into SPF chicks via the oral/nasal route. The bursa/body weight ratios and cycle threshold values at 4 and 7 days post challenge were examined. At 4 days, five of the viruses did not cause a significant drop in bursa/body weights but at 7 days post challenge all the viruses caused a significant drop in these ratios. The histopathology in these bursas, was consistent with the brusa/body weight ratios. Based on the real-time RT-PCR Cycle Threshold (Ct) values, the original bursa samples had similar quantities of viral RNA (Ct between 15 and 18). Ct values do not directly detect the quantity of infectious virus however they are an indication of viral load. EID50 titers are traditionally used to determine virus quantities in samples but these too can be problematic because the ability of the viruses to replicate in eggs can vary. This was observed in our study. The EID50 titers ranged from 10 to 10 and did not correlate with Ct values or the ability of the viruses to cause bursa lesions by 4 days post-challenge. Of the four viruses with the highest EID50 titers only one caused significant bursa lesions at 4 days post challenge. The data indicate that 4 days post-challenge may be too early to assess pathogenicity in SPF chicks for some IBDV strains even when the starting EID50 titers of the viruses are relatively high. We concluded that all 8 isolates were pathogenic in SPF chicks as predicted by their VP2 sequence.
Publications
- Type:
Book Chapters
Status:
Awaiting Publication
Year Published:
2020
Citation:
Jackwood, D. J. (2020) Infectous Bursal Disease Virus. Encylocpedia of Virology, 4th Edition. Elsevier, Ltd.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Myint, Ohnmar, Mathurot Suwanruengsri, Kenji Araki, Uda Zahli Izzati, Apisit Pornthummawat, Phawut Nueangphuet, Naoyuki Fuke, Takuya Hirai, Daral J. Jackwood and Ryoji Yamaguchi. The bursa atrophy at 28 days old by the variant infectious bursal disease virus makes a negative economic impact on broiler farms in Japan. Avian Path. 2020. DOI: 10.1080/03079457.2020.1822989
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Higgins, J., E. Wallner-Pendleton, L. Michel, and D. Jackwood. An Unusual Case of IBD in a Commercial Pullet Flock. Abstr. AAAP Virtual Meeting Poster, August 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Jackwood, D. J., L. O. Michel and M. L. Kimber. Pathogenicity of infectious bursal disease viruses isolated from commercial poultry with immune suppression related disease. Abstr. AAAP Virtual Meeting Poster, August 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Michele, L. O., M. L. Kimber and D. J. Jackwood. Expression and characterization of avian reovirus sigma C-MBP fusion proteins as ELISA antigens. Abstr. AAAP Virtual Meeting, Poster, August 2020.
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