Prophylactic use of canine parvovirus monoclonal antibody induces blockade of vaccinal canine parvovirus immunization similar to maternally derived passive immunity.

Abstract

OBJECTIVE: To determine initial antibody titer, degradation profile, and duration of passive antibody blockade of active immunization by modified-live viral (MLV) canine parvovirus (CPV-2) vaccine following CPV monoclonal antibody (CPMA) prophylactic subcutaneous (SC) administration to CPV-2-naïve puppies. METHODS: Purpose-bred, CPV-2-seronegative male and female Beagle dogs, 7 to 8 weeks of age, were randomized to CPMA treatment (n = 13) and control (7) groups. Dogs were commingled and group housed in a shower-in/shower-out facility. At study day 0, dogs were administered either 0.1 mL/kg body weight CPMA SC or an equivalent volume of saline. Sera collected weekly over 140 days were assayed via hemagglutination inhibition and serum virus neutralization. All dogs were administered a commercially available MLV vaccine containing CPV-2 in combination with other core vaccine viruses at 3-week time points beginning at study day 42. RESULTS: All control dogs remained seronegative through day 42 and seroconverted to CPV-2 after the initial dose of MLV vaccine. By study day 1, the CPMA-treated group showed a mean passive hemagglutination inhibition titer of 1,674. The average degradation rate was calculated at R2 = 0.97, with a mean half-life of 18.9 days. Twelve of 13 (92%) in the treated group seroconverted after a fourth vaccination on day 105. CONCLUSIONS: Prophylactic CPMA at 0.1 mL/kg body weight SC can block active CPV-2 immunization for 15 weeks when given to seronegative puppies. CLINICAL RELEVANCE: Initial puppy vaccination series should be extended after CPMA prophylactic use.