Molecular Markers for Infectious Diseases: Challenges and Prospects
Pei-Jer Chen National Taiwan University
November, 2007
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HHMI Bulletin Winter 2005;25-30
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Microbial genomes multiply
Nature
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Nature V.429 P.345-346
Specific Detection of Infectious Agents DNA RNA Proteins
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Protein-encoding sequences as a gene Functional molecules coding-sequences as a gene
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Biomarkers for Infectious Diseases
Culture: Gold Standards. Protein molecule detection. Nucleic Acids: RNA or DNA. Host Biomarkers: Immune responses Genetic markers.
Protein-based Diagnosis
Enzyme activities: AST, ALT, etc. Protein molecule detection: specific, high affinity antibodies. RIA, ELISA and western blots. Sensitive, reliable and convenient after 30 years development. It has become an indispensable part of daily research and clinical practices. Simple and useful spot test (rapid test for flu or pregnancy)
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Limitations
Sensitivity limited the natural affinity of specific antibody. Time-consuming in development: taking years to prepare and find high affinity antibodies Difficult to carry out large-scale, parallel detections of multiple proteins. Biohazards: requiring natural and functional proteins which can be infectious.
Kleinman et al, Bailliere's Clinical Hepatology 2000
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Limitations
Sensitivity limited the natural affinity of specific antibody. Time-consuming in development: taking years to prepare and find high affinity antibodies Difficult to carry out large-scale, parallel detections of multiple proteins. Biohazards: requiring natural and functional proteins which can be infectious.
Detection of HBV (Surface Ag): Evolution Story takes 30 years
RPHA (1970) RIA or EIA: 5 ng/ml (1980) ELISA: 1 ng/ml (1985). ELISA: 0.1 ng (1996) ELISA: 0.05 ng (2002)
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Limitations
Sensitivity limited the natural affinity of specific antibody. Time-consuming in development: taking years to prepare and find high affinity antibodies Difficult to carry out large-scale, parallel detections of multiple proteins. Biohazards: requiring natural and functional proteins which can be infectious.

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