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Infection and Immunity, September 1999, p. 4637-4645, Vol. 67, No. 9
Departments of Microbiology & Molecular
Genetics and Medicine, University of California
Received 25 February 1999/Returned for modification 13 April
1999/Accepted 7 June 1999
Serotypes A and B of the relapsing fever spirochete Borrelia
turicatae produce different disease manifestations in infected mice. Whereas serotype B causes more severe arthritis and reaches higher densities in the blood of mice than serotype A, serotype A
invades the central nervous system earlier than serotype B during infection. These differences between serotypes A and B in mice are
associated with the expression of different surface proteins, VspA and
VspB, respectively, in the culture medium. To determine whether these
proteins, in particular, VspB, are also expressed in vivo,
scid mice infected with B. turicatae were
studied. The expression of VspB by spirochetes in the blood was
demonstrated in Coomassie blue-stained polyacrylamide gels and Western
blots with a specific monoclonal antibody. Indirect immunofluorescence and immunoperoxidase studies confirmed the expression of VspB in the
blood and also demonstrated VspB expression in the joints and heart.
The gene for VspB was next identified and cloned by using partial amino
acid sequencing, reverse transcriptase PCR, and a specific monoclonal
antibody. The vspB gene encodes a protein of 216 amino
acids that is 68% identical to VspA of B. turicatae and 44 to 56% identical to representative Vsp and OspC lipoproteins of other
Borrelia spp. The processed VspB protein was distinguished from 26 other Vsp and OspC proteins by a high predicted isoelectric point at 9.39. The promoter region for vspB was similar to
the promoter region for the vsp33 gene of Borrelia
hermsii and for the ospC gene of Borrelia
burgdorferi, two genes known to be environmentally regulated.
These studies established that the virulence-associated VspB protein is
expressed by spirochetes in the mouse and that VspB is a novel member
of the Vsp-OspC family of proteins.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Characterization of VspB of Borrelia
turicatae, a Major Outer Membrane Protein Expressed in Blood and
Tissues of Mice

Irvine, Irvine,
California 926971; Department of
Microbiology, University of Texas Health Science Center at San Antonio,
San Antonio, Texas 782842; and
Department of Neuropathology, Armed Forces Institute of Pathology,
Washington, D.C. 203063
*
Corresponding author. Mailing address: Department of
Microbiology & Molecular Genetics, B240 Med Sci I, University of
California
Irvine, Irvine, CA 92697-4025. Phone: (949) 824-5626. Fax:
(949) 824-8598. E-mail: abarbour{at}uci.edu.
Present address: Medical Entomology Research and Training
Unit/Guatemala, Division of Parasitic Diseases/NCID, Centers for Disease Control and Prevention, Chamblee, GA 30341.
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