Feline Immunodeficiency Virus (FIV) – NAVLE Study Guide

Overview and Clinical Importance

Feline Immunodeficiency Virus (FIV) is a lentivirus in the Retroviridae family that causes progressive immune dysfunction in domestic and wild cats worldwide. First isolated in 1986 by Pedersen and Yamamoto at UC Davis, FIV is analogous to Human Immunodeficiency Virus (HIV) in its pathogenesis and clinical manifestations, though it is strictly species-specific and poses no zoonotic risk to humans.

FIV affects approximately 2.5-4.4% of cats in the United States, with higher prevalence in outdoor, intact male cats due to the primary transmission route of bite wounds. Understanding FIV is essential for the NAVLE as it frequently appears in questions regarding retroviral infections, diagnostic testing interpretation, and management of immunocompromised feline patients.

Etiology and Virology

Viral Classification and Structure

FIV is a lentivirus (family Retroviridae), characterized by slow disease progression and lifelong persistent infection. The virion consists of a diploid single-stranded RNA genome (~9400 nucleotides) enclosed within a protein capsid (p24), surrounded by a matrix protein (p17) and lipid envelope derived from the host cell membrane.