Effects of passive transfer of immunity on results of diagnostic tests for antibodies against feline immunodeficiency virus in kittens born to vaccinated queens

• Published in: Journal of the American Veterinary Medical Association Vol. 225; no. 10; pp. 1554 - 1557
• Main Authors: MacDonald, K, Levy, J.K, Tucker, S.J, Crawford, P.C
• Format: Journal Article
• Language: English
• Published: United States 15-11-2004
• Subjects: Age Factors; Animals; Animals, Newborn; antibodies; Antibodies, Viral - blood; blood serum; Cat Diseases - immunology; Cat Diseases - prevention & control; Cat Diseases - transmission; Cats; colostrum; disease diagnosis; feline acquired immunodeficiency syndrome; Feline immunodeficiency virus; Female; females; Immunization, Passive - veterinary; Immunodeficiency Virus, Feline - immunology; Infectious Disease Transmission, Vertical - prevention & control; Infectious Disease Transmission, Vertical - veterinary; kittens; Lentivirus Infections - immunology; Lentivirus Infections - prevention & control; Lentivirus Infections - transmission; Lentivirus Infections - veterinary; maternal immunity; maternal milk; parturition; seroconversion; specific pathogen-free animals; Specific Pathogen-Free Organisms; vaccination; Vaccination - veterinary; Viral Vaccines - administration & dosage; Viral Vaccines - immunology; weaning
• ISSN: 0003-1488; 1943-569X
• DOI: 10.2460/javma.2004.225.1554

To determine whether passive transfer of immunity affects results of diagnostic tests for antibodies against FIV in kittens born to vaccinated queens.
Experimental trial.
12 specific-pathogen-free queens and their 55 kittens.
Queens were vaccinated with a whole-virus FIV vaccine prior to breeding. Serum was obtained from the queens on the day of parturition and from the kittens on days 2 and 7, then weekly until results of tests for antibodies against FIV were negative for 2 consecutive weeks. Milk was collected from the queens daily for the first week and then weekly. Serum and milk were tested for antibodies against FIV with 2 commercial assays.
Antibodies against FIV were detected in serum obtained from the queens on the day of parturition and in the milk throughout lactation. All kittens tested positive for antibodies against FIV at 2 days of age. At 8 weeks of age, 30 (55%) kittens tested positive with 1 of the commercial assays, and 35 (64%) tested positive with the other. All kittens tested negative for antibodies against FIV by 12 weeks of age.
Results suggest that kittens readily absorb antibodies against FIV in colostrum from vaccinated queens and that these antibodies may interfere with results of commercially available tests for FIV infection past the age of weaning. Currently licensed diagnostic tests for FIV infection are unable to distinguish among kittens with antibodies against FIV as a result of infection, passive transfer from infected queens, and passive transfer from vaccinated queens.