Infectious Bursal Disease Virus (IBDV) routinely infects commercial chickens and presents a critical problem for poultry producers. The virus causes both its own clinical disease and immunosuppression (breakdown of the chicken's immune system), which invites other secondary diseases. IBDV spreads very quickly amongst chickens, infecting an entire flock in a matter of days from the first infection. Once infected, a bird without prior immunity will often become sick within hours and die within days. The chance of mortality becomes even greater with the added threat from secondary infections (which themselves cannot be combated because infected birds fail to respond to their vaccines).

Certain vaccine programs have been developed to combat IBDV. Despite their moderate success, however, commercial producers continue to experience heavy economic loss from this disease. This project seeks to further understand the cellular causes of IBDV in order to pave the way for more effective control measures.

Method

In this study, we are examining the role that T cells (those not producing antibodies) play both in the pathogenesis of the disease and in the immunosuppression caused by the virus. We are also considering the possible role that T cells play in regenerating bursal follicles (glandular sacs) with B cells (antibody-producing cells) that are destroyed by the infection.

Results

Several types of T cells have been found in the infected bursa, including those that both negatively suppress the immune response system and positively react against IBDV in laboratory testing. Our data shows that bursal T cells induced by the virus may play a key role in protection against the virus. Thus, we have been able to begin work with applied researchers for the development of more effective vaccine than is currently available.

Minnesota produces over 60 million broiler and layer chickens worth $245 million in a given year. No concrete figures are available regarding IBDV. However, the state's chicken producers are estimated to lose several million dollars annually to the virus and its related diseases. Likewise, chicken producers throughout the U.S. and abroad lose hundreds of millions of dollars to IBDV each year. These losses come from both lost market potential when infected chickens die and the high expenses incurred for current vaccination methods (40 billion doses are estimated to be sold worldwide every year).

While our efforts to identify more effective control measures have been successful at the basic research level, we are just beginning to move into the applied stage. The immediate aim is to develop a vaccine that reduces the immunosuppression caused by the disease. This would minimize the secondary incidence of disease wrought by IBDV, and in turn increase flock performance. Our ultimate goal is to reduce IBDV-related losses in the chicken industry by 50%.

Minnesota County
All Counties

Primary Researcher
Jagdev Sharma
sharm001@umn.edu

Participating Individuals
2 Graduate Students

Department
Veterinary Pathobiology

Government Funding Type
State