IMMUNOHISTOCHEMICAL ANALYSIS OF THE LYMPHOID ORGANS OF DOGS NATURALLYINFECTED WITH CANINE-DISTEMPER VIRUS

The pathogenesis of acute canine distemper in three naturally infected dogs was investigated. The lymphoid organs showed atrophy without sec ondary follicles. The distribution of canine distemper virus (CDV) ant igens was examined immunohistochemically with monoclonal antibodies sp ecific for canine Thy-1, immunoglobulin (Ig) M, CD4, CD8, CD21 and CD4 5RB, and anti-measles virus nucleocapsid protein serum. The viral anti gens were located in the T-cell-dependent areas and in the follicles o f lymphoid organs; they were observed mainly in the Thy-1-, or CD4-pos itive cells, but also in the CD8-, CD21-, or IgM-positive cells. The r esults indicated that Thy-1-positive and CD4-positive T cells serve as major target cells for CDV during the acute stage of infection. (C) 1 995 Academic Press Limited