1. ¹Department of Neurology and Neuroscience, UMDNJ-New Jersey Medical School, Newark, NJ, USA
2. ²Center for the Study of Emerging Pathogens, UMDNJ-New Jersey Medical School, Newark, NJ, USA
3. ³Center for Comparative Medicine, University of California at Davis, Davis, CA, USA

Correspondence: Dr D Cadavid, MD, Department of Neurology and Neuroscience, UMDNJ-New Jersey Medicine School, 185 South Orange Avenue, MSB H506, Newark, NJ 07103, USA. E-mail: Cadavidi@umdnj.edu

Received 9 March 2004; Revised 13 July 2004; Accepted 16 July 2004; Published online 27 September 2004.

Abstract

To investigate cardiac involvement in the non-human primate (NHP) model of Lyme disease, we inoculated 39 adult Macaca mulatta with Borrelia burgdorferi sensu stricto strains N40 (BbN40) by needle (N=22, 14 immunocompetent (IC), seven permanently immunosuppressed (IS), and four transiently immunosuppressed (TISP)) or by tick-bite (N=4, all TISP) or strain 297 (Bb297) by needle (N=2 IS), or with B. garinii strains Pbi (N=4, 2 TISP and 2 IS), 793 (N=2, TISP) or Pli (N=2, TISP). Five uninfected NHPs were used as controls. Infection and inflammation was studied in the hearts and the aorta removed at necropsy 2–32 months after inoculation by (1) H&E and trichrome-staining; (2) immunohistochemistry and digital image analysis; (3) Western blot densitometry; and (4) TaqMan RT-PCR. All NHPs inoculated with BbN40 became infected and showed carditis at necropsy. The predominant cells were T cells, plasma cells, and macrophages. There was increased IgG and IgM in the heart independent of immunosuppression. The B-cell chemokine BLC was significantly increased in IS-NHPs. There was increased deposition of the complement membrane attack complex (MAC) in TISP and IS-NHPs. The spirochetal load was very high in all BbN40-inoculated IS-NHPs but minimal if any in IC or TISP NHPs. Double-immunostaining revealed that many spirochetes in the heart of BbN40-IS NHPs had MAC on their membranes. We conclude that carditis in NHPs infected with B. burgdorferi is frequent and can persist for years but is mild unless they are immunosupressed.