Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/29/1999
Publication Date: N/A
Citation: Interpretive Summary: Tissues from chickens infected with different strains of Newcastle disease virus (NDV) were examined for presence of macrophages and interferon gamma production (IFN-gamma). Macrophages are immune cells found in all tissues of the body that originate in bone marrow. They aid in clearance of infectious agents and are stimulated by IFN-gamma produced by T-cells. Consequently, IFN-gamma aids the cellular immune response resulting in an increased efficiency of removing intracellular pathogens, such as viruses. Chickens infected with highly virulent NDV had increased numbers of macrophages and increased production of IFN-gamma. Consequently, anti-viral therapy that enhance these immune functions may be important for protection of chickens against NDV.
Technical Abstract: Formalin-fixed, paraffin-embedded spleen and intestinal tissues were harvested at 2 days postinfection from 4-wk-old White Rock chickens infected with five different strains of Newcastle disease virus (NDV). The five strains represented all three NDV pathotypes. Viral replication and IFN gamma expression, as determined by riboprobe in situ hybridization, were detected only in those chickens infected with velogenic viscerotropic NDV (VVND) strains. Macrophage antigen expression, an indicator of macrophage activation, was determined by immunohistochemistry using a macrophage-specific antibody, CVI-ChNL-68.1. Presence of macrophage antigen was most prominent in VVNDV-infected chickens. The distribution of this antigen within tissues was far more diffuse than the staining for viral mRNA. The presence of IFN mRNA was detected in the spleen and intestinal lymphoid tissue of VVNDV-infected chickens. There was also increased macrophage antigen expression in the mesogen-infected birds, but it was less dramatic than in tissues from VVNDV-infected chickens. One of two lentogen-infected birds had evidence of increased macrophage antigen expression only in the spleen.