Immunofluorescent studies on chronic pneumonia in swine with experimentally induced African swine fever.
Chronic pneumonia experimentally produced in 14 pigs with African swine fever (ASF) virus was studied by immunofluorescene (IF) and histopathologic techniques. Frozen sections prepared from pulmonary tissues of the infected pigs were stained with fluorescein-conjugated antiserums against ASF viral antigen, porcine immunoglobulin G (IgG), procine complement (C), and porcine fibrinogen. The viral antigen(s) was mainly seen in macrophages and cell debris in alveolar walls and lumens. This finding indicates that the virus replicated in the cytoplasm of alveolar macrophages that subsequently degenerated and released the viral antigen. Diffuse immunoglobulin (Ig) deposition was found in necrotic cells and debris. Immunoglobulin also was seen bound to intracytoplasmic inclusion bodies in some degenerating alveolar macrophages. This finding indicates that antibody against ASF viral antigen(s) excluded from blood circulation or produced by local immunocytes (or both) reacted with viral antigen at intramacrophage and extramacrophage levels and resulted in the formation of insoluble antigen-antibody (Ag-Ab) complexes. The participation of C in the immune complex was evident in the early stage of the pneumonia, but was less evident in the subsequent extensive, progressive necrotic processes. Fibrin deposits were visible only in the early necrotic area of alveolar walls and lumens. Possible mechanisms inducing extensive necrosis are discussed.
D000357:African Swine Fever / Q000382:microbiology*; D000818:Animals; D000936:Antigen-Antibody Complex; D000956:Antigens, Viral; D003165:Complement System Proteins / Q000032:analysis; D004267:DNA Viruses; D005337:Fibrin / Q000032:analysis; D005340:Fibrinogen / Q000032:analysis; D005455:Fluorescent Antibody Technique; D007106:Immune Sera; D007074:Immunoglobulin G / Q000032:analysis; D008168:Lung / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D009336:Necrosis; D011024:Pneumonia, Viral / Q000276:immunology / Q000662:veterinary*; D011650:Pulmonary Alveoli / Q000276:immunology; D011817:Rabbits / Q000276:immunology; D013552:Swine; D013553:Swine Diseases / Q000276:immunology*
D000936:Antigen-Antibody Complex; D000956:Antigens, Viral; D007106:Immune Sera; D007074:Immunoglobulin G; D005337:Fibrin; D005340:Fibrinogen; D003165:Complement System Proteins