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DEVELOPMENT OF BIOMARKER OF EXPOSURE TO VIRAL PATHOGENS
Citation:
LI, L. AND A. P. DUFOUR. DEVELOPMENT OF BIOMARKER OF EXPOSURE TO VIRAL PATHOGENS. Presented at FOCIS, San Francisco, CA, June 01 - 05, 2006.
Impact/Purpose:
To develop and evaluate methods for detecting biomarkers of exposure to infectious agents. In vitro tests for products associated with cellular and humoral immunity, such as IFN-� and antibodies, will be developed. The initial infectious agents to be investigated include viruses on the contaminant candidate list, such as coxsackievirus, echovirus, adenovirus and calicivirus.
Description:
Interferon gamma (IFN-γ) was selected as a biomarker for a viral exposure study. Twelve-week-old BALB/c mice were intraperitoneally injected with 0.2ml of 104 PFU/ml of coxsackievirus B3 or B4 diluted in phosphate-buffered saline (PBS). Control mice were injected with PBS only. Four months after viral infection mouse thymus and spleen were collected. T lymphocytes were isolated from the organs and assayed for proliferation to release IFN-γ under ex vivo stimulation (incubation) with viral antigens, a mitogen PHA and PBS respectively. The level of IFN-γ released by T lymphocytes was examined by antibody-capture chemiluminescent ELISA. A marked increase in the level of IFN-γ was observed when T cells from coxsackievirus B3 infected mice were incubated with B3 virus but not B4 and PBS. This indicated that coxsackievirus B3- sensitized T cell receptors recognized only T cell epitopes from B3 virus not B4. By the same token, primed T cells from mice infected by coxsackievirus B4 were not stimulated to produce IFN-γ when they were incubated with B3 virus and PBS. T cells from mice injected with PBS did not release IFN-γ because they did not recognize both B3 and B4 viruses. These T cells did release IFN-γ under stimulation of PHA. Our results demonstrated that IFN-γ produced by memory (sensitized or primed) T cells is virus-specific and can be used as a biomarker in viral infection studies. The data also demonstrated that the memory T cell receptor can distinguish different T cell epitopes from highly structurally related coxsackievirus B3 and B4 when the sensitized T cells were directly stimulated by the viruses ex vivo. The results of this study may be extended to human exposure studies related to microbial pathogens.