molecular epidemiology, molecular epidemiology.pptx

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1. Molecualr Epidemiology For Infectious and Parasitic Diseases Ali Raza Vance 2017-ag-1433 Anas Ashraf 2012-ag-

2. Definition T erm "molecular epidemiology“---coined by Kilbourne in 1973 in his article "The molecular epidemiology of influenza” A science that deals with T he contribution of genetic and environmental risk factors identified at the molecular and biochemical level to T he etiology, Distribution and C ontrol of disease in families and populations (J. Dorman)

3. Applications of Molecular Epidemiology Molecular epidemiology allows for an understanding of: T he molecular outcomes I mplications of diet, lifestyle E nvironmental exposure, how and exposures result in acquired genetic mutations and how these mutations are distributed throughout selected populations. Molecular epidemiological studies are able to provide additional understanding of previously identified. risk factors and disease mechanisms.

4. Will facilitate the ability of scientists to conduct etiologic research. Will increase our knowledge about the determinants of disease. Will contribute to the development of approaches for disease prevention. Will improve public health. Provides personalized estimates of risk may empower susceptible individuals to intervene on: - Diet, lifestyle, Environmental exposures. Helps to build Targeted approaches may be more effective in preventing disease.

5. Weaknesses & Challenges Limitations (Slattery, M. 2002) of molecular epidemiological studies are similar in nature to those of generic epidemiological studies, that is, Samples of convenience - both of the target population and genetic information Small sample sizes Inappropriate statistical methods Poor quality control Poor definition of target populations

6. Objectives of Molecular Epidemiology Conduct descriptive and analytical studies to evaluate gene / environment interactions in disease etiology . Provide risk factor -specific morbidity rates for purposes of education and intervention.

7. Molecular epidemiology tools Identification of Aetiological Agent(s) Conventional Methods Culture Enzyme-linked immunosorbent assay (ELISA) Antibodies & Monoclonal antibodies based assays, LFA, agglutination etc. Nucleic acid based Methods DNA hybridization for known genes Direct sequencing of one or more regions Multilocus sequence typing (MLST)

8. • PCR (nucleic acid amplification) based Methods – Amplification of a single target specific to a pathogen – Ligase chain reaction (LCR) – Loop mediated isothermal amplification (LAMP) • Protein based Methods – Western blot or immunoblotting .

9. PCR (nucleic acid amplification) based Methods – Amplification of a single target specific to a pathogen Ligase chain reaction (LCR) – Loop mediated isothermal amplification (LAMP) Protein based Methods – Western blot or immunoblotting .

10. Molecular epidemiology tools Fingerprinting Conventional Serotyping , Antibiotic susceptibilities ( Antibiogram ), Toxinotyping , Biotyping , Phenotyping Nucleic acid based Plasmid profiles, Plasmid replicon typing Restriction fragment length polymorphism (RFLP) Pulsed field gel electrophoresis (PFGE) Segmented RNA gel electrophoresis, Ribosomal RNA gel electrophoresis Direct sequencing of one or more regions and now NGS Multilocus sequence typing (MLST)

11. Molecular epidemiology tools PCR Based Amplification of a single target specific to a pathogen Targeting known repetitive sequences ( enterobacterial repetitive intergenic consensus sequences (ERIC), R epetitive extragenic palindromic sequences (REP), double repetitive element (DRE), BOX, I nsertional sequence (IS), P olymorphic guanine/cytosine-rich repetitive sequences (PGRS)) Random primers (randomly amplified polymorphic DNA (RAPD), arbitrary primed PCR (AP-PCR) Restriction endonuclease of a single amplified product Amplified fragment length polymorphism (AFLP)

12. Protein based Multilocus enzyme electrophoresis (MLEE) Enzyme-linked immunosorbent assay (ELISA) Gene expression Reverse transcriptase PCR Microarray technologies