PROTECTION OF NEONATAL KITTENS AGAINST FELINE IMMUNODEFICIENCY VIRUS-INFECTION WITH PASSIVE MATERNAL ANTIVIRAL ANTIBODIES

Objective: Maternal antibodies from either vaccinated or feline immuno deficiency virus (FIV)-infected female cats (queens) were evaluated fo r their ability to protect kittens against homologous FIV infection. D esign: Kittens that received different levels of maternal antiviral an tibodies from either vaccinated or infected queens were inoculated wit h homologous FIV at 1 week post-parturition and monitored for FIV infe ction. Maternal antiviral antibodies in the kittens were also measured and compared to the level of FIV infection. Methods: Kittens at 1 wee k post-parturition were inoculated intraperitoneally with five median cat infectious doses of FIVPet. FIV infection was monitored by virus i solation for infectious FIV and by nested polymerase chain reaction fo r proviral DNA. Virus-neutralizing (VN) antibodies and antibodies to F IV transmembrane peptide and core protein were also monitored througho ut the 25 weeks. Results: Neonatal kittens that received high levels o f antiviral antibodies from either vaccinated or infected queens were protected from FIV inoculation. Kittens that received low levels of ma ternal antiviral antibodies were not completely protected from similar FIV inoculation. Protection correlated more closely with the level of maternal VN antibodies than the anti-p25 antibodies transferred to th e kittens. The unprotected kittens born to infected queens were not in fected from vertical transmission because all littermates that were no t FIV-inoculated remained free of FIV infection. Conclusions: Maternal antiviral antibodies, including VN antibodies, from either vaccinated or infected queens protected neonatal kittens from FIV inoculation. T hus, maternal antiviral antibodies play a key role in preventing or li miting infection in neonates and such antiviral immunity can be provid ed by vaccinated queens.