Cardiac conduction abnormalities in a mouse model of Lyme borreliosis

Background: Borrelia Burgdorferi (BB) induces cardiac conduction abnormalit ies in infected humans. Mice models of Lyme disease have been developed, ho wever their electrophysiologic (EP) properties of conduction are unknown. Methods: Seventy-six C3H/J mice (BB infected and age- and gender-matched co ntrols) underwent blinded in vivo EP studies. In a first phase of the study , 40 male C3H/J mice were divided into 2 groups: Group (A) mice were infect ed at age 3 (weeks) and studied at 5, and Group (B) mice were infected at 9 and studied at 11. In a second phase, 36 female mice were divided into 2 g roups: Group (C) mice were infected at 3 weeks and studied at 5, and Group (D) mice were infected at 3 and studied at 11. Results: Infected mice of group (A) and (C) had wider QRS complexes (21.0 /-1.6 versus 17.3 +/-1.3 ms, p less than or equal to0.0001 and 20.3 +/-2.1 versus 18.5 +/-1.7, p = 0.05, respectively) compared to the healthy control s (HC). Infected mice of group (B) and group (D) were similar to the HC. In all groups, the presence of conduction abnormalities correlated very close ly with the amount of inflammation on pathology. Conclusion: This study describes the first EP mouse model of Lyme carditis. C3H/J mice exhibit conduction abnormalities that are reversible 8 weeks af ter inoculation, closely paralleling the resolution of inflammation on path ology. This model can be a valuable tool in the developing and testing of n ew modalities for the prevention and treatment of Lyme carditis.