Source: OHIO STATE UNIVERSITY submitted to NRP
MOLECULAR AND BIOLOGICAL CHARACTERIZATION OF INFECTIOUS BURSAL DISEASE VIRUSES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
1020542
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 2019
Project End Date
Sep 30, 2024
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
OHIO STATE UNIVERSITY
1680 MADISON AVENUE
WOOSTER,OH 44691
Performing Department
Food Animal Health Research Program
Non Technical Summary
A direct measure of problems related to IBDV induced immune suppression is difficult. Thus, the poultry industry has a false sense that the longstanding vaccines prepared from classic and variant viruses are adequate. The increased use and success of autogenous IBD vaccines and studies on the molecular basis for antigenic drift indicate current vaccines are inadequate. The spread of vvIBDV and genome reassorted vvIBDV throughout the world including the U.S. suggests vaccines used for this acute strain of the virus are also not working. Since a universal vaccine that would protect against all antigenic strains of IBDV is not technically possible with current technology, our strategy is to identify mutant strains of the virus and then quickly produce a custom VLP vaccine for that strain.
Animal Health Component
30%
Research Effort Categories
Basic
30%
Applied
30%
Developmental
40%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
31132991101100%
Knowledge Area
311 - Animal Diseases;

Subject Of Investigation
3299 - Poultry, general/other;

Field Of Science
1101 - Virology;
Goals / Objectives
The initial use of a VLP vaccine would be in breeder flocks to produce maternal immunity in their progeny. These vaccines would replace autogenous vaccines and commercial inactivated-vaccines currently being used in breeder flocks. If these VLP antigens can be successfully used in a micro-encapsulation formula to stimulate active immunity in young chicks, they could also provide a superior and safer alternative to live-attenuated vaccines. The scope of this Hatch Project is to determine the efficacy of VLP vaccines for newly identified mutant strains of IBDV. We will also use micro-encapsulation to examine the potential of these vaccines to protect growing broilers as their maternal immunity to IBDV wanes.
Project Methods
We will use RT-PCR and sequencing of the hvVP2 gene to identify new mutations in IBDV strains causing disease in commercial poultry flocks. The baculovirus platform will be used to express IBDV proteins and to generate VLP vaccines to the IBDV strains with new amino acid mutations in the hvVP2 protein. These VLP vaccines will be used to conduct vaccination/challenge studies with homologous and heterologous IBDV strains to determine the efficacy of the vaccines for the new virus and the degree of cross-protection against other antigenic strains of IBDV. Finally, we will micro-encapsulate VLP constructs in biodegradable nanoparticles. This vaccine will be administered by aerosol and orally (water) to vaccinate broiler chicks that contain maternal immunity to IBDV. We will test the resulting immune response in these birds by challenging the chicks with multiple antigenic types of IBDV.

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.