Effects of Recent Leptospira Vaccination on Whole Blood Real‐Time PCR Testing in Healthy Client‐Owned Dogs

• Published in: Journal of veterinary internal medicine Vol. 26; no. 1; pp. 149 - 152
• Main Authors: Midence, J.N., Leutenegger, C.M., Chandler, A.M., Goldstein, R.E.
• Format: Journal Article
• Language: English
• Published: United States 01-01-2012
• Subjects: Animals; Bacterial Vaccines - administration & dosage; Bacterial Vaccines - immunology; Canine leptospirosis; Diagnostic; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Dog Diseases - blood; Dog Diseases - immunology; Dog Diseases - prevention & control; Dogs; Female; Leptospira - genetics; Leptospira - immunology; Leptospirosis - blood; Leptospirosis - microbiology; Leptospirosis - prevention & control; Leptospirosis - veterinary; Male; Prospective Studies; Random Allocation; Real-Time Polymerase Chain Reaction - veterinary; Real‐time PCR; Vaccination - veterinary; Vaccine
• ISSN: 0891-6640; 1939-1676
• DOI: 10.1111/j.1939-1676.2011.00852.x

Background
Bacterin‐based canine Leptospira vaccines could present a challenge for the use of whole blood real‐time polymerase chain reaction (PCR) as a diagnostic tool. Recent vaccination could induce positive results if the targeted DNA fragment is present within the vaccine and in the blood of the recently vaccinated dog.
Objectives
The objective of this study was to assess whether 2 available 4‐serovar vaccines induce a positive real‐time PCR reaction in the blood of healthy recently vaccinated dogs.
Animals
Twenty healthy dogs.
Methods
This was a prospective study. Dogs were assigned to 1 of 2 vaccine groups. Both vaccines were culture‐based and include Leptospira interrogans serovars Pomona, Canicola, and Icterohaemorrhagiae and Leptospira kirschneri serovar Grippotyphosa. Whole blood for real‐time PCR and serum for the microscopic agglutination test (MAT) were collected prior to and 3 and 7 days after vaccination and weekly thereafter for 8 weeks. Two real‐time PCR tests targeting 2 different genes were performed independently in a blinded fashion.
Results
Both Leptospira vaccines produced positive real‐time PCR reactions when assayed undiluted or diluted 1 : 100 in canine blood. However, blood samples drawn from all dogs at all time points after vaccination were negative on PCR. All dogs developed MAT titers.
Conclusions and Clinical Importance
Recent vaccination with 2 commercially available vaccines does not interfere with the use of real‐time PCR for the identification of acute Leptospira infection in dogs.