Detection of Canine Parvovirus DNA From Blood and Feces Collected From Healthy Puppies After Administration of Modified Live Vaccine
J.H. Burton; J.K. Veir; A.K. Morris; J.R. Hawley; M.R. Lappin
Polymerase chain reaction (PCR) assays are now being used to detect canine parvovirus (CPV) DNA in samples from dogs to aid in the clinical diagnosis of infection. However, little information exists on whether administration of modified live CPV containing vaccines affects the test results. The objective of this study was to determine the duration of detectable levels of CPV DNA in blood and CPV antigen in feces from healthy puppies vaccinated with a modified-live CPV containing vaccine.
Of the 12, six week old puppies selected for study, six were from a bitch with a high CPV antibody titer (1:640) and six were from a bitch with a low CPV antibody titer (1:10). On day 0, all puppies were seronegative, regardless of maternal antibody status. A modified-live CPV containing vaccine was administered SQ on day 0 and blood and feces were collected on days 0, 2, 5, 7, 10, and 14. Conventional CPV PCR was performed on DNA extracted from each of the whole blood samples. Two commercially available CPV antigen ELISAs were performed on each of the fecal samples.
CPV antigen was detected in feces of one dog by one of the ELISAs on day 5. CPV DNA was amplified from blood of some dogs on day 2 (8 dogs), day 5 (7 dogs), day 7 (8 dogs), day 10 (6 dogs), and day 14 (12 dogs). CPV antibody titers and CPV PCR results were available for all dogs on days 7, 10, and 14. Of the 26 samples with positive CPV PCR results, 21 were concurrently positive for CPV antibodies (Titer range 64-16,384; median titer = 16,384).
The modified live vaccine used here was unlikely to result in positive results in the fecal antigen ELISAs studied. However, the CPV PCR assay could detect CPV DNA in many vaccinated puppies regardless of antibody titer. Positive CPV PCR assay results from blood need to be interpreted cautiously, especially in recently vaccinated, previously naïve dogs.