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Persistent Ehrlichia chaffeensis infection occurs in the absence of functional major histocompatibility complex class II genesHuman monocytic ehrlichiosis is an emerging tick-borne disease caused by the rickettsia Ehrlichia chaffeensis. We investigated the impact of two genes that control macrophage and T-cell function on murine resistance to E. chaffeensis. Congenic pairs of wild-type and toll-like receptor 4 (tlr4)- or major histocompatibility complex class II (MHC-II)-deficient mice were used for these studies. Wild-type mice cleared the infection within 2 weeks, and the response included macrophage activation and the synthesis of E. chaffeensis-specific Th1-type immunoglobulin G response. The absence of a functional tlr4 gene depressed nitric oxide and interleukin 6 secretion by macrophages and resulted in short-term persistent infections for > or =30 days. In the absence of MHC-II alleles, E. chaffeensis infections persisted throughout the entire 3-month evaluation period. Together, these data suggest that macrophage activation and cell-mediated immunity, orchestrated by CD4(+) T cells, are critical for conferring resistance to E. chaffeensis.
Document ID
20040088600
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Ganta, Roman Reddy
(College of Veterinary Medicine, Kansas State University Manhattan, Kansas 66506, United States)
Wilkerson, Melinda J.
Cheng, Chuanmin
Rokey, Aaron M.
Chapes, Stephen K.
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Publication Information
Publication: Infection and immunity
Volume: 70
Issue: 1
ISSN: 0019-9567
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Cell Biology
Non-NASA Center

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