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Infection and Immunity, August 2001, p. 4958-4968, Vol. 69, No. 8
Gonçalo Moniz Research Center, Oswaldo Cruz
Foundation, Brazilian Ministry of Health,
40295-001,1 and School of Pharmacy,
Federal University of Bahia, 40000 Salvador,2
Brazil; School of Public Health, University of California at
Berkeley, Berkeley, California 94720-73603;
Division of Infectious Diseases, Veterans Affairs Greater Los
Angeles Healthcare System,4 and
Department of Medicine, UCLA School of
Medicine,5 Los Angeles, California 90095-1688;
School of Clinical Medicine and Research, University of the
West Indies, Bridgetown, Barbados6; and
Division of International Medicine and Infectious Diseases,
Weill Medical College of Cornell University, New York, New York
100217
Received 23 January 2001/Returned for modification 21 March
2001/Accepted 7 May 2001
Leptospirosis is an emerging zoonosis caused by pathogenic
spirochetes belonging to the genus Leptospira. An
understanding of leptospiral protein expression regulation is needed to
develop new immunoprotective and serodiagnostic strategies. We used the humoral immune response during human leptospirosis as a reporter of
protein antigens expressed during infection. Qualitative and quantitative immunoblot analysis was performed using sera from 105 patients from Brazil and Barbados. Sera from patients with other
diseases and healthy individuals were evaluated as controls. Seven
proteins, p76, p62, p48, p45, p41, p37, and p32, were identified as
targets of the humoral response during natural infection. In both acute
and convalescent phases of illness, antibodies to lipopolysaccharide were predominantly immunoglobulin M (IgM) while antibodies to proteins
were exclusively IgG. Anti-p32 reactivity had the greatest sensitivity
and specificity: positive reactions were observed in 37 and 84% of
acute- and convalescent-phase sera, respectively, while only 5% of
community control individuals demonstrated positive reactions. Six
immunodominant antigens were expressed by all pathogenic leptospiral
strains tested; only p37 was inconsistently expressed. Two-dimensional
immunoblots identified four of the seven infection-associated antigens
as being previously characterized proteins: LipL32 (the major outer
membrane lipoprotein), LipL41 (a surface-exposed outer membrane
lipoprotein), and heat shock proteins GroEL and DnaK. Fractionation
studies demonstrated LipL32 and LipL41 reactivity in the outer membrane
fraction and GroEL and DnaK in the cytoplasmic fraction, while p37
appeared to be a soluble periplasmic protein. Most of the other
immunodominant proteins, including p48 and p45, were localized to the
inner membrane. These findings indicate that leptospiral proteins
recognized during natural infection are potentially useful for
serodiagnosis and may serve as targets for vaccine design.
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.8.4958-4968.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Leptospiral Proteins Recognized during the Humoral
Immune Response to Leptospirosis in Humans
*
Corresponding author. Mailing address: Centro de
Pesquisas Gonçalo Moniz; Fundação Oswaldo Cruz/MS,
Rua Waldemar Falcão, 121; 40295-001 Salvador, Bahia, Brazil.
Phone: (55 71) 356-4320, ext. 243. Fax: (55 71) 356-2155. E-mail:
aik2001{at}med.cornell.edu.
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