PROLIFERATION AND APOPTOSIS IN INFECTION WITH INFECTIOUS BURSAL DISEASE VIRUS - A FLOW CYTOMETRIC STUDY

Programmed cell death, or apoptosis, is involved in the normal physiol ogy of many immunocompetent organs, including lymphocytes of the bursa of Fabricius in chickens. Involvement of apoptosis has also been desc ribed in some viral diseases such as AIDS. The purpose of this work wa s to study the potential role of apoptosis in the pathogenesis of Gumb oro disease in the bursa of Fabricius. Our results show that 1-3 days after infection of young chickens with infectious bursal disease virus , the number of apoptotic cells increases and cellularity and prolifer ation decrease. Because of the dynamic nature of bursal lymphocyte pop ulations and the involvement of apoptosis in lymphocyte cell physiolog y, the increased level of cells undergoing apoptosis may be due to an impairment in the withdrawal of apoptotic cells. A concomitant increas e in macrophages in infected bursae and a dramatic decrease in cellula rity suggest that an increase in apoptosis may be an important cause o f cell depletion.