Feline Immunodeficiency Virus (FIV) is the causative agent of feline AIDS and a member of the lentivirus group in the family Retroviridae. FIV has a world-wide distribution with a prevalence of around 5% in healthy cats. FIV is transmitting mainly by biting. It can also be transmitted from mother to kitten during the prenatal period. The virus establishes a persistent infection then follows an asymptomatic phase lasting several years in which the cat is clinically healthy. However, over time the immune function in the cat deteriorates and opportunistic infections (especially of the respiratory and gastrointestinal tracts, lymphomas or neurological disorders) arise. The development of effective anti-FIV strategies is of great veterinary interest. No specific antiviral drug for FIV is currently available. The preferred initial tests are ELISA or immunochromatographic test, which detect antibodies recognizing viral structural proteins (such as the capsid protein p24) and offer the advantage of speed and convenience.