Table 4.

Cats that received a higher number of annual FIV re-vaccinations were more likely to have antibodies against p24 12 months post-vaccination. In total, 6/10 and 4/10 cats in the annual vaccination group tested positive on day 0 for antibodies against p24 and gp40, respectively, demonstrating that these cats had a duration of antibody response of at least 12 months since their last FIV vaccination. Cats administered a higher number of annual FIV vaccinations were more likely to test positive for anti-p24 antibodies at 12 months post-vaccination (p = 0.076; multivariate logistic regression). There was no trend observed with anti-gp40 antibody ELISA results at 12 months in cats administered a higher number of annual FIV vaccinations (p = 0.23; multivariate logistic regression). Samples were considered antibody positive if NF values were greater than the mean NF of FIV-unvaccinated controls × 2 standard deviations. NF = negative fold, MIA = microsphere immunoassay testing, and ELISA = laboratory-based anti-FIV transmembrane peptide ELISA testing.

Anti-p24 Antibodies (MIA) 12 Months Post-Vaccination	Anti-gp40 Antibodies (ELISA) 12 Months Post-Vaccination	No. of Annual FIV Vaccinations (Prior to Enrollment)
−	−	0
−	+	1
+	−	1
−	−	2
+	−	2
+	−	2
−	+	2
+	+	2
+	−	3
+	+	7
6/10 cats	4/10 cats