HISTOPATHOLOGY AND VIRAL-ANTIGEN DISTRIBUTION IN LYMPH-NODES OF CATS NATURALLY INFECTED WITH FELINE IMMUNODEFICIENCY VIRUS

Lymph nodes from cats with natural feline immunodeficiency virus (FIV) infection were examined histopathologically for characterization of l esions in the symptomatic and terminal stages. The localization of vir al antigen was also studied in the nodes by immunohistochemistry using a monoclonal antibody to FIV p24. In a node of persistent generalized lymphadenopathy stage, follicular hyperplasia was prominent and the v iral antigen was demonstrated predominantly in the follicular lymphocy tes and tingible body macrophages. In cats died at AIDS related comple x stage, the lymph nodes showed either mixed follicular hyperplasia an d involution, involution, or mixed involution and depletion. The lymph nodes in those died at AIDS stage showed considerable destruction of the nodal architecture with involution and depletion of lymphoid folli cles. In this terminal stage, the viral antigen was seen prominently i n histiocytes/macrophages of the sinus. These findings observed in the dead cats were similar to the lymph node changes seen in human AIDS a ssociated with HIV infection. It was suggested that sequential histolo gic changes from follicular hyperplasia to depletion via involution to ok place in the FIV infected lymph node with persistence of FIV antige n.