Evaluation of the murine immune response to Xenopsylla cheopis flea saliva and its effect on transmission of Yersinia pestis
Arthropod-borne pathogens are transmitted into a unique intradermal microenvironment that includes the saliva of their vectors. Immunomodulatory factors in the saliva can enhance infectivity; however, in some cases the immune response that develops to saliva from prior uninfected bites can inhibit i...
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Published in | PLoS neglected tropical diseases Vol. 8; no. 9; p. e3196 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Public Library of Science
01.09.2014
Public Library of Science (PLoS) |
Subjects | |
Online Access | Get full text |
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Summary: | Arthropod-borne pathogens are transmitted into a unique intradermal microenvironment that includes the saliva of their vectors. Immunomodulatory factors in the saliva can enhance infectivity; however, in some cases the immune response that develops to saliva from prior uninfected bites can inhibit infectivity. Most rodent reservoirs of Yersinia pestis experience fleabites regularly, but the effect this has on the dynamics of flea-borne transmission of plague has never been investigated. We examined the innate and acquired immune response of mice to bites of Xenopsylla cheopis and its effects on Y. pestis transmission and disease progression in both naïve mice and mice chronically exposed to flea bites.
The immune response of C57BL/6 mice to uninfected flea bites was characterized by flow cytometry, histology, and antibody detection methods. In naïve mice, flea bites induced mild inflammation with limited recruitment of neutrophils and macrophages to the bite site. Infectivity and host response in naïve mice exposed to flea bites followed immediately by intradermal injection of Y. pestis did not differ from that of mice infected with Y. pestis without prior flea feeding. With prolonged exposure, an IgG1 antibody response primarily directed to the predominant component of flea saliva, a family of 36-45 kDa phosphatase-like proteins, occurred in both laboratory mice and wild rats naturally exposed to X. cheopis, but a hypersensitivity response never developed. The incidence and progression of terminal plague following challenge by infective blocked fleas were equivalent in naïve mice and mice sensitized to flea saliva by repeated exposure to flea bites over a 10-week period.
Unlike what is observed with many other blood-feeding arthropods, the murine immune response to X. cheopis saliva is mild and continued exposure to flea bites leads more to tolerance than to hypersensitivity. The immune response to flea saliva had no detectable effect on Y. pestis transmission or plague pathogenesis in mice. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 The authors have declared that no competing interests exist. Conceived and designed the experiments: CFB COJ BJH. Performed the experiments: CFB AKV COJ DG MPR. Analyzed the data: CFB DG BJH. Contributed reagents/materials/analysis tools: DG MPR. Contributed to the writing of the manuscript: CFB BJH. Critiqued manuscript: AKV COJ DG MPR. Current address: Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon |
ISSN: | 1935-2735 1935-2727 1935-2735 |
DOI: | 10.1371/journal.pntd.0003196 |