Feline Immunodeficiency Virus (FIV): Immunopathogenesis

Feline immunodeficiency virus is a lentiviral infection of domestic cats fo und worldwide. At least five subtypes of FIV have been identified; subtype variance may be responsible for the differences seen in pathogenesis and cl inical progression. Biting is the most common mode of transmission, but FIV can also be transmitted in utero, via infected milk, and across several mu cosal surfaces. FIV infection results in progressive impairment of the immu ne system, even in clinically normal animals. These included loss of CD4+ ( helper) lymphocytes, dysregulation of cytokine production, and altered lymp hocyte function. Hematologic abnormalities such as cytopenias and hyperglob olinemia are frequently encountered in FIV-infected cats.