Cytokines changes in beagle dogs vaccinated and challenged with virulent Leptospira strains

ABSTRACT

Objective: To determine the immune response of dogs by measuring the levels of cytokines tumour necrosis factor (TNF) α, interleukin (IL)-4 and interferon (IFN) γ pre- and post-vaccination with a locally produced killed whole-celled Leptospira vaccine. Design and Methodology: Three separate vaccine-challenge experiments involving 21 beagle dogs were conducted. Study 1 (duration of immunity), used 6 vaccinated and 3 non-vaccinated (control) dogs. Vaccination was done at 12 and 16 weeks of age and challenged at 12 months of age with 1-2.5 x 108 live Leptospira. Study 2 (onset of immunity) also contained the same number of dogs as study 1. Vaccination was done at 12 and 16 weeks of age and challenged at 18 weeks of age. Study 3 (onset of immunity study), as study 2, used 4 vaccinated and two control dogs but challenged with 1-2.5 X 109 live Leptospira. Blood samples were collected to measure the levels of TNF α, IL-4 and IFN γ in dogs 2 days pre-challenge and daily thereafter until day 7 post-challenge. Results: For cytokine TNF α, pre-challenge levels for Study 1, 2 and 3 were 0.0000, 0.0755 and 0.0705 pg/ml which increased to a maximum post-challenge level of 49.05 pg/ml, 0.47 pg/ml and 1.667pg/ml respectively. For cytokine IL-4 and IFN γ the level increased from 0.00 pg/ml to a maximum post-challenge level of 52.67 pg/ml, 243.34 pg/ml and 989.14 pg/ml; and 281.91 pg/ml, 1223.85 pg/ ml and 1778.95 pg/ml respectively. Conclusion: The locally produced Leptospira vaccine induced immune response post-challenge with live Leptospira.