Pathogenic and immunosuppressive effects of avian pneumovirus in turkeys.
Avian pneumovirus (APV) causes a respiratory disease in turkeys. The virus has been associated with morbidity and mortality due to secondary infections. Our objective was to determine if APV caused immunosuppression in the T-cell or B-cell compartments and to study the pathogenesis of the disease in APV maternal antibody-lacking 2-wk-old commercial turkeys. APV was administered by the eyedrop/intranasal route. Observations were made for gross lesions, viral genome, and T-cell mitogenesis and cytokine secretion at 3, 5, 7, 14, and 21 days postinoculation (DPI). During the acute phase of the disease that lasted for about 1 wk, the turkeys exposed to APV showed clinical signs characterized by nasal discharge and sinus swelling. Virus genome was detected by in situ hybridization in cells of turbinates and trachea at 3 and 5 DPI. At 3 and 5 DPI, spleen cells of the birds infected with APV markedly decreased proliferative response to concanavalin A (Con A). Con A and lipopolysaccharide stimulation of spleen cells from virus-exposed turkeys resulted in accumulation of nitric oxide-inducing factors (NOIF) in the culture fluid. NOIF were not detected in culture fluids of Con A-stimulated spleen cells of virus-free turkeys. APV did not compromise the antibody-producing ability of turkeys against several extraneous antigens such as Brucella abortus and tetanus toxoid.
Chary
Parag
P
Department of Veterinary PathoBiology, College of Veterinary Medicine, University of Minnesota, St. Paul 55108, USA.
Rautenschlein
Silke
S
Njenga
M K
MK
Sharma
Jagdev M
JM
D000281:Administration, Intranasal; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D016207:Cytokines / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D017403:In Situ Hybridization / Q000662:veterinary; D018111:Pneumovirus / Q000276:immunology* / Q000302:isolation & purification / Q000472:pathogenicity*; D018186:Pneumovirus Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D011201:Poultry Diseases / Q000276:immunology / Q000473:pathology / Q000821:virology*; D013154:Spleen / Q000166:cytology / Q000821:virology; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors; D014422:Turkeys
D000914:Antibodies, Viral; D016207:Cytokines