No evidence of vertical transmission of naturally acquired feline immunodeficiency virus infection.

A naturally occurring feline immunodeficiency virus (FIV) infection in a closed breeding colony of cats, was studied for a period of 9 months. The colony consisted of 25 adult cats, of which six proved to be infected with FIV as judged by serological examination and virus isolation. In all, 48 kittens were monitored for levels of antibodies against FIV during their first 6 months of life. All the kittens (n = 30) born of FIV-infected queens showed maternal antibodies against FIV, although these declined to undetectable levels by the age of 5 months. Antibodies against FIV were not shown in any of 18 kittens born of FIV-negative queens. An attempt to isolate the virus from 12 kittens between 2 and 6 weeks of age did not succeed. None of the cats in the colony seroconverted during the observation period. In conclusion, neither vertical nor horizontal transmission of FIV infection were demonstrated in the colony during the 9-month investigation period.