Microbio 310 1st Edition Lecture 29 Outline of Last Lecture I. 30.6 Antibody Genes and DiversityII. 30.7 T Cell Receptors: Proteins, Genes, and DiversityIII. 30.8 Clonal Selection and ToleranceIV. 30.9 T Cell and B Cell ActivationV. 30.10 Cytokines and ChemokinesVI. 31.1 Isolation of Pathogens from Clinical SpecimensVII. 31.2 Growth-Dependent Identification MethodsVIII. 31.3 Antimicrobial Drug Susceptibility TestingIX. 31.4 Safety in the Microbiology LaboratoryX. 31.5 Immunoassays for Infectious DiseaseXI. 31.6 Polyclonal and Monoclonal AntibodiesXII. 31.7 In Vitro Antigen–Antibody Reactions: SerologyXIII. 31.8 AgglutinationXIV. 31.9 ImmunofluorescenceOutline of Current Lecture I. 31.10 Enzyme Immunoassay and RadioimmunoassayII. 31.11 ImmunoblotsIII. 31.12 Nucleic Acid HybridizationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.IV. 31.13 Nucleic Acid AmplificationV. 32.1 The Science of EpidemiologyVI. 32.2 The Vocabulary of EpidemiologyVII. 32.3 Disease Reservoirs and Epidemics VIII. 32.4 Infectious Disease TransmissionIX. 32.5 The Host Community Current Lecture31.10 Enzyme Immunoassay and Radioimmunoassay• Enzyme immunoassay (EIA) or enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA) methods– Very sensitive immunological assays– Widely used in clinical diagnostic and research applications– EIA employs covalently bonded enzymes to label antibody molecules– RIA employs radioisotopes to label antibody molecules– Both allow detection of antigen–antibody complexes• Three different EIA methodologies are frequently used:– Direct EIA • Detection of antigen– Indirect EIA • Detection of antibody– Competitive EIA• Detection of antigen– Known amount of antigen-specific antibody– Mix with patient antigen– Add to antigen-coated wells– Color is inverse to amount of antigen in sample• Hundreds of other clinically useful EIAs have been developed• Radioimmunoassay (RIA)– Employs radioisotopes as antibody or antigen conjugates instead of enzymes– Isotope iodine-125 is commonly used as the conjugate– Used to measure rare serum proteins, such as• Human growth hormone, glucagon, vasopressin, testosterone, and insulin– Also used in some tests for illegal drugs31.11 Immunoblots• Immunoblot (Western blot)– Electrophoresis of proteins, followed by transfer to a membrane and detection by addition of specific antibodies– Immunoblot methods detect antibodies to specific antigens or the antigens themselves31.12 Nucleic Acid Hybridization• Sensitive methods based on nucleic acid analyses are widely used in clinical microbiology• These methods do not depend on:– Pathogen isolation or growth– Detection of an immune response to the pathogen• Nucleic acid probes hybridize with complementary specimen DNA or RNA31.13 Nucleic Acid Amplification• Polymerase Chain Reaction (PCR)– Presence of amplified gene segment confirms presence of pathogen– Reverse transcriptase PCR (RT-PCR)• Uses pathogen-specific RNA to make cDNA– Quantitative real-time PCR (qPCR)• Uses fluorescent labeled PCR products• Almost immediate results32.1 The Science of Epidemiology• Epidemiology– The study of the occurrence, distribution, and determinants of health and disease in a population (establishing cause and effect)• In developed countries infectious diseases cause fewer deaths than noninfectious diseases– Worldwide, infectious disease accounts for 30% of all deaths• Even in developed countries, new diseases are emerging– Examples: West Nile fever, Chagas, Chickungunya (new tropical disease, in Caribbean, known for brutal pain, no treatment, simply takes time to shed it)• Effective control of infectious disease remains a challenge• Pathogen must replicate and grow inside a host to cause a disease• A well-adapted pathogen lives in balance with its host– Chronic infections: host and pathogen survive; long-term infections• New pathogens sometimes emerge for which the host has no resistance– Acute infections: pathogen can be a selective force; rapid and dramatic onset• Epidemiologists trace the spread of disease to identify its origin and mode of transmission32.2 The Vocabulary of Epidemiology• A disease is an epidemic when it occurs in a large number of people in a population at the same time– A pandemic is very widespread, usually worldwide • An endemic disease is constantly present in a population, usually at low levels• The incidence of a disease is the number of new cases of the disease in a given period of time• The prevalence of a disease is the total number of new and existing cases in a population in a given time (always bigger than incidence) • A disease outbreak occurs when a number of cases of a disease are reported in a short period of time• Diseased individuals who show no or mild symptoms have subclinical infections– Subclinical individuals are called carriers• Mortality is the incidence of death in a population• Morbidity of a disease refers to the incidence of disease including fatal and nonfatal diseases• Disease progression– Infection: the organism invades and colonizes the host– Incubation period: the time between infection and onset of symptoms– Acute period: the disease is at its height– Decline period: disease symptoms are subsiding– Convalescent period: patient regains strength and returns to normal32.3 Disease Reservoirs and Epidemics• Reservoirs are sites in which infectious agents remain viable and from which infection of individuals can occur--where did it come from (ex: fruit bats are reservoir for Ebola)– A number of infectious diseases are caused by pathogens that propagate in humans and animals– For other pathogens, nonliving matter serves as reservoirs• For example, soil is a reservoir for Clostridium tetani, the cause of tetanus, and for C diff• Zoonosis is any disease that primarily infects animals, but is occasionally transmitted to humans (animal vector as part of diseases’ life cycle) Ex: West Nile, the plague, malaria– Control of a zoonotic disease in the human population may not eliminate the disease as a potential public health problem– Certain infectious diseases have complex life cycles involving an obligate transfer from a nonhuman host to humans followed by transfer back to the