Apoptosis in Chicken Embryos Induced by the.pdf

j . Comp. Path. 1995 VoL 112, 327 338 Apoptosis in Chicken Embryos Induced by the Infectious Bursal Disease Virus A. C. V a s c o n c e l o s and K. M. Lain Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, Universi~ of Cal~rnia, Davis, CA 95616, USA Summary Fifteen-day-old fertile eggs (specific pathogen-free) were inoculated with the infectious bursal disease virus (IBDV) by the allantoic route and were opened and examined 2, 4 or 6 days later. The bursas of Fabricius (BFs) were collected and processed for DNA extraction, flow cytometry, and light and electron microscopy. Cellular DNA was subjected to electrophoresis on 1 5 % agarose gel and stained with ethidium bromide. Intense internucleosomal DNA fragmentation was detected in IBDV-infected bursas. Cytograms from cell suspensions derived from infected BFs displayed an increased population of cells with either high density and small size (apoptotic cells) or small size and high uptake of ethidium bromide (necrotic cells). Light and electron microscopical examination of the IBDV-infected BFs revealed death of lymphoid cells without surrounding inflammatory reaction, but with con- densation of nuclear chromatin, crescent formation, and nuclear and cellular fragmentation. These data indicated that infection of chicken embryos with IBDV induced apoptosis in bursal lymphoid cells. Introduction Apoptosis or programmed cell death takes place during organogenesis, meta- morphosis, hormone or growth factor removal-induced involution and during maturation of lymphoid cells (Wyllie, 1981; Motyka and Reynolds, 1991; Tomei and Cope, 1991; Liu et al., 1992). It causes nuclear fragmentation and cellular breakdown into apoptotic vesicles without any release of cellular contents into the interstitum, and consequently without inflammatory reaction in the tissues (Cohen, 1991). This type of cellular self-destruction can also be brought about by pathological stimul