Experimental maedi virus infection in sheep: cellular and humoral immune response during three years following intranasal inoculation.
A long-term experiment in sheep inoculated intranasally with 2 strains of Norwegian maedi virus was carried out in 2 groups of Norwegian Dala sheep (7 sheep/group). Virus-specific cellular immune response was assayed in the lymphocyte transformation test sequentially during 3 years after sheep were inoculated in group 1 and 4 times in the 3rd year in group 2. Humoral immune response was assayed by immunodiffusion, complement-fixation, and neutralization tests on sequential serum samples collected from the 2 groups. Attempts to isolate virus were made. All group 1 sheep showed transient and irregularly recurring cellular immune responses. In group 2, 6 of the 7 sheep gave similar responses. The frequency of virus isolations was low compared with that reported by various research workers using other breeds for studying experimental maedi-visna infection. Precipitating antibodies were detected earlier, and in more animals, than were complement-fixing antibodies. Both were, however, detected later and less frequently than were reported by other research workers. There was a marked difference in the capability of the 2 maedi virus strains to induce neutralizing antibodies. The sequential sera usually showed distinct differences in neutralizing capacity of the virus strains, indicating that they are antigenically different.
D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis; D000917:Antibody Formation; D003168:Complement Fixation Tests / Q000662:veterinary; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007111:Immunity, Cellular; D005779:Immunodiffusion / Q000662:veterinary; D009297:Nasal Mucosa / Q000382:microbiology; D011021:Pneumonia, Progressive Interstitial, of Sheep / Q000276:immunology*; D012756:Sheep; D013997:Time Factors; D014790:Visna-maedi virus / Q000276:immunology / Q000302:isolation & purification
D000914:Antibodies, Viral; D000949:Histocompatibility Antigens Class II