Host Pathogen Interactions Pt. II PDF

Host Pathogen Interactions Pt. 1I  WHY DO WE CARE? HOST-PATHOGEN INTERACTIONS I  Before we learned about how the immune system fights pathogens  Now we will elaborate on what happens when pathogens thwart the immune system  Host-pathogen interactions play a critical role in the e...

Host Pathogen Interactions Pt. 1I  WHY DO WE CARE? HOST-PATHOGEN INTERACTIONS I  Before we learned about how the immune system fights pathogens  Now we will elaborate on what happens when pathogens thwart the immune system  Host-pathogen interactions play a critical role in the establishment AND stages of infectious disease  As physicians, you need to understand these complex interactions in order to treat and/or prevent disease depending on what stage of infectious disease  CLASS OBJECTIVES  Differentiate between the 6 Stages of Establishment of Infectious Disease & 5 Stages (Periods) of Infectious Disease  Define and give examples of virulence factors  Further breakdown RON & learn about transmission to new hosts  Define what is needed for nutritionally compatible niche (i.e. oxygen- aerobe v. anaerobe, facultative v. obligate; & iron)  Identify mechanisms of cell death and how microorganisms perform them  Identify the three types of bacterial toxins & give examples of each  Compare & contrast antigenic drift & antigenic shift FIVE STAGES (PERIODS) OF INFECTIOUS DISEASE From DITKI Host Pathogen Interactions I  VIRULENCE FACTORS HELP ESTABLISH INFECTION/DISEASE  VIRULENCE FACTORS- enable pathogen to replicate and disseminate inside a host by either subverting or eluding host defenses.  Every pathogen has their own combination of virulence factors; some unique, & some shared  Shared by multiple strains:  Adhesins- Surface proteins that bind to host cells  Capsules that inhibit phagocytosis  Toxins- e.g. Lipopolysaccharide (LPS)  Unique:  Toxins: e.g. Botulinum toxin  Gp120- facilitates HIV entry into host cells  Etc. (we’ll learn a ton of these over the semester)  GOAL: SURVIVAL  3 demands of free-living microbes: RON  Avoid being washed away (colonize the surfaces of host cells). (Occupancy)  Find a nutritionally compatible niche. (Nutrition)  Survive innate and adaptive defenses. (Resistance) *I wanted to spell RON to help you remember, but we’re going to go a bit out of order today- NOR  Transmit to a new host  NUTRITIONALLY COMPATIBLE NICHE  Nutritional requirements often reflect ecological habitat (i.e. soil is minimal, human body is complex)  Will select for environments that support their nutritional requirements  Human body ideal microenvironment for microbes: sugars, vitamins, minerals, etc.  Oxygen  Anaerobes (“an”-without + “aero”- air + “bios”- life)  Aerobes (“aero”-air + “bios”- life)  Facultative- occurring optionally in response to circumstances  Obligate- restricted to a particular function  Iron  Bacteria need iron for synthesis of cytochromes & enzymes  Human body (low free iron) & bacteria compete  Body decreases free iron concentration in bacterial infection  Bacteria excrete siderophores, iron-chelating agents, to steal iron from host  OCCUPANCY- SURFACE COLONIZATION  Adhesins-cell-surface components of bacteria that facilitate adhesion  Type of virulence factor  Bind to special receptors- highly specific  Gram- bacteria  Fimbrial adhesins  Invasin (nonfimbrial surface protein) bind to integrin  Gram+ bacteria  Surface proteins that bind to fibronectin  *Remember*- hospitalized patients deficient in fibronectin= >Gram- infections  Both (but not all can have)  Capsules- composed of polysaccharides that cover the cell wall; principal antiphagocytic that prevents access of *rare exception of Gram+ bacteria having fimbriae, but the leukocytes to the underlying cell wall elements know it’s “unique” to Gram- bacteria for exam RESISTANCE- SURVIVING THE CONSTITUTIVE & INDUCED DEFENSES  How do microbes evade the host’s first line defenses? 1. Defending against complement 2. Subverting phagocytosis 3. Surviving inside phagocytes 4. Becoming intracellular 5. Immunosuppression 6. Diversion of Lymphocyte Function 7. Proteolysis of Antibodies 8. Latency 9. Antigenic Variation (& Antigenic Drift & Shift)  1. DEFENDING AGAINST COMPLEMENT  Complement- Circulating plasma proteins that recognize molecular components of pathogens & become activated  Causes opsonization & killing of bacteria  Opsonization= antibodies attached to surface of pathogen to mark them for destruction  Classical, Alternative, and Mannose- Binding Lectin activation pathways Figure 8-1 MMD 2. SUBVERTING PHAGOCYTOSIS  Phagocytosis- the ingestion of bacteria or other material by phagocytes (like macrophages & neutrophils)  Killing phagocytes  Avoiding neutrophil extracellular traps (NETS)  Escaping ingestion- capsules  3. SURVIVING INSIDE PHAGOCYTES  Inhibition of lysosome fusion with phagosomes  Escape into the cytoplasm  Resistance to lysosomal enzymes  Inhibition of phagocytes oxidative pathway 4. BECOMING INTRACELLULAR  Some cells thrive inside the phagocytes  Can trigger infected cells to fuse with uninfected neighbor cells so they can spread  Some use host’s cytoskeleton & actin to spread into adjacent cells  Ex. Listeria monocytogenes (what I studied in undergrad); facultative intracellular bacteria 5. IMMUNOSUPPRESSION  Immunosuppression  Damage immune cells like T cells, or inhibiting cytokine secretion  Ex. HIV  6. DIVERSION OF LYMPHOCYTE FUNCTION  Diversion of lymphocyte function: Superantigens  Type of antigen that results in excessive activation of immune system  Non-specific activation of T-cells & widespread cytokine release  Ex. Certain streptococci  7. PROTEOLYSIS OF ANTIBODIES  Proteolysis of antibodies  Make proteases (protein that breaks down proteins) that cleave a specific antibody, immunoglobulin A (IgA)  Sometimes a piece of IgA remains (antigen binding fragment- Fab), which prevents other antibodies from binding- fabulation  Found in pathogenic bacteria  8. LATENCY  Latency  Pathogen is present in the body, but exists in a resting state without producing more of itself  Not affected by immune system, long-lasting  Can reactivate in times of stress or decreased immune function  Herpes virus, HIV, tuberculosis 9. ANTIGENIC VARIATION  Changing surface antigen  Trypanosomes- Trypanosoma brucei  Variable surface glycoprotein  Hundreds of genes code for different antigens  When antibodies are created, they switch to a different antigen  N. Gonorrhoeae  Changes surface pilin (protein that makes pili)  Influenza viruses  Hemagglutinin-binds cell surface receptors, Neuraminidase- changes the receptors  Antigenic Drift- every 2-3 years.  A/Wisconsin/67/2005 (H3N2)-like virus & A/Hong Kong/4801/2014 (H3N2)  Antigenic Shift- every 10 years.  2009 swine flu- H1N1 with swine, avian, and human genes TEST YOUR KNOWLEDGE #1  How do microbes evade the host’s first line defenses?  Defending against complement  Subverting phagocytosis  Surviving inside phagocytes  Becoming intracellular  Latency  Antigenic variation  Immunosuppression  MECHANISMS THAT DAMAGE THE HOST DURING INFECTION 1. Pathological Alterations of Metabolism  Produce toxin that mimic hormones or other pharmacologic effectors 2. Mechanical Causes of Damage  Mechanical obstruction due to buildup or blockage of lymphatics  Common with parasites like roundworm 3. Damage Caused by Host Response  Cytokine storm  Overactivation of complement system  Superantigens MECHANISMS THAT DAMAGE THE HOST DURING INFECTION- CELL DEATH 4. Lysis- disintegration of cell by rupture of cell wall or membrane  Produces toxin to damage cell membrane  Clostridia lyse red blood cells & cause gas gangrene  Multiplies inside cell & leads to lysis from inside  Rickettsiae produces peroxide  Multiplies inside host, but immune cells eradicate the cell  Mycobacteria 5. Apoptosis (ahp-uh-toe-sis)-Programmed cell death  Part of normal cell cycle  HIV & herpes- premature apoptosis  Epstein-Barr block apoptosis to make immortal host cell  MECHANISMS THAT DAMAGE THE HOST DURING INFECTION- BACTERIAL TOXINS  A range of proteins that alter the normal metabolism of host cells with deleterious effects on the host  Can have intracellular, extracellular, or extracellular matrix targets 1. Intracellular Intracellular Extracellular  Exotoxins  Type III cytotoxins  Type IV to VII cytotoxins 2. Extracellular  Endotoxin (LPS)  Membrane-damaging toxins  Superantigens 3. Extracellular matrix  Exoenzymes TEST YOUR KNOWLEDGE #2  Which is not a mechanism that damages the host during infection (and why?)? A. Brugia malayi filaria blocking lymph node B. Cytokine storm in Covid-19 C. Exotoxin production by Clostridium perfringens D. Phagocytosis of Rhinovirus TEST YOUR KNOWLEDGE #3  You are working in a microbiology lab and receive a blood sample from a patient suffering from a bacterial infection. As you are gram staining, you notice the bacteria seem to be dying off quite quickly and you hypothesize that this is due to the presence of oxygen. What type of bacteria is your most-likely culprit? A. Obligate aerobe B. Obligate anaerobe C. Facultative aerobe ALSO A SCIENTIST Abigail Salyers, PhD (1942-2013) - Nuclear Physics, PhD, George Washington University (switched to Micro during postdoc at Virginia Polytechnic)  “Mother of human microbiome research”  First female tenured professor at University of Illinois, Champaign-Urbana (1983)  Authored 5 books & >200 scientific publications  Revenge of the Microbes- PopSci book on antibiotic resistance  President of the American Society for Microbiology during US anthrax epidemic (2001) so she developed public policies & educated postal workers about biosafety  For funzies: https://www.youtube.com/watch?v=xf2PbVHgdEM General Principles of Laboratory Dx WHY DO WE CARE? GENERAL PRINCIPLES OF LABORATORY DIAGNOSTICS  CLASS OBJECTIVES  Describe the four diagnostic principles  Assess the performance of different diagnostic tests  Aka apply sensitivity, specificity, PPV, NPV (with math, but I’ll try to pick easy numbers so it’s not difficult math)  Understand when to use tests from each of the 4 diagnostic principles (especially clinically) & the meaning of the results  Be able to diagnose infections by culture (phenotypically)  Describe molecular and genetic approaches to studying bacteria ASSESSING THE PERFORMANCE OF DIAGNOSTIC TESTS  True positive- pathogen positive, test positive  True negative- pathogen negative, test negative  False positive- pathogen negative, test positive (Type 1 Error)  False negative- pathogen positive, test negative (Type 2 Error)  Sensitivity- ability of test to correctly identify those with disease (true positive rate)  Specificity- ability of test to correctly identify those without the disease  Positive predictive value- probability that subjects with a positive test will truly have the disease  Negative predictive value- probability that subjects with a negative test truly don’t have the disease DIAGNOSTIC SENSITIVITY AND SPECIFICITY: HOW RELIABLE IS THE TEST?  Interpretation of test results requires an understanding of the test’s reliability prior to diagnosis or treatment  No test is perfect; every testing method produces several false-positive & false-negative results  How much emphasis should be placed on a particular test depends on sensitivity & specificity  Sensitivity- probability that the test will be positive in a patient who has the disease in question  Specificity- probability that the result will be negative in a patient who does not have the disease  Sensitivity & specificity of a test can be determined by using a 2 × 2 table (a, b, c, & d are actual numbers of observations, not proportions) TRUE VS FALSE  A true positive is an outcome where the model correctly predicts the positive outcome  A true negative is an outcome where the model correctly predicts the negative outcome  A false positive is an outcome where the model incorrectly predicts the positive outcome  A false negative is an outcome where the model incorrectly predicts the negative outcome  LET’S APPLY IT!  Imagine the evaluation of a diagnostic test developed to predict the dreaded disease Examinus paralysis, commonly known as “brain freeze,” among students about to take an exam. Data from previous experience indicates that: True positive True negative -------------------------- -------------------------- True pos + false neg False pos + true neg WHAT IS THE SENSITIVITY? WHAT IS THE SPECIFICITY THE FOUR DIAGNOSTIC PRINCIPLES 1. Microscopic 2. Cultivation and 3. Measurement of a 4. Detection of pathogen- examination of patient identification of pathogen-specific immune specific macromolecules samples. microorganisms from response in the patient. in patient samples patient samples.  1. DIAGNOSING INFECTIONS BY MICROSCOPY- STAINS  Gram stains & acid-fast stains  Presence of bacteria in a normally sterile body fluid (i.e. CSF, blood, urine)  Less useful from a nonsterile body site (ie skin)  Staining properties & morphology help with species identification & empirical selection of antibiotics  A diagnosis  Giemsa stain- systemic protozoal infections  Lugol’s iodine stains- intestinal helminths  Silver stains- systemic fungal infection  1. DIAGNOSING INFECTIONS BY MICROSCOPY- ANTIBODY BASED IDENTIFICATION  Specific antibodies enhance accuracy of microscopic identification  A monoclonal antibody to epitope= most specific  A polyclonal antibody can be least specific  Depends on what you’re looking for and cross-reactivity  Direct immunofluorescence: fluorophore is conjugated to the antibody  Indirect immunofluorescence: unlabeled primary antibody is added, then an anti-primary fluorophore secondary antibody is added to bind to the unlabeled primary 1. DIAGNOSING INFECTIONS BY MICROSCOPY- ANTIBODY BASED IDENTIFICATION. DIRECT & INDIRECT IMMUNOFLUORESCENCE Immunofluorescence pic because I love it (Yes, I took this one, no, it’s not bacteria)  2. DIAGNOSING INFECTIONS BY CULTURE  Agar-based media and in a broth medium under both aerobic and anaerobic conditions  Blood culture  Direct inoculation of blood into nutrient broth & incubation to check for microbial growth  Sub-cultured & transferred to agar plates for identification  OR lysis-centrifugation technique- RBCs lysed and remaining dense material inoculated in agar medium & plated  Culture identification  Phenotypic properties: motility, utilization of various nutrient substrates, enzymes produced, etc.  Antibody-based techniques  Selective media can identify specific cultures 2. COMMON CULTURES: EMB & MACCONKEY AGAR 2. DIAGNOSING INFECTIONS BY CULTURE  Antimicrobial sensitivity testing- tested for susceptibility to antimicrobial agents 3. MEASURING THE ANTIBODY RESPONSE TO INFECTION- WESTERN BLOT  Serology- diagnostic examination of blood serum, esp. regarding immune response to pathogens  Western blot- one of the most specific serologic methods  Pathogen’s antigens are separated based on size using electrophoresis  Antigens are then “blotted” onto solid support & incubated with patient’s serum to see if antibodies bind to pathogen-specific or cross- reactive antigens 3. MEASURING THE ANTIBODY RESPONSE TO INFECTION- ELISA  Enzyme-linked immunosorbent assay (ELISA)  Solid-phase assay= pathogen or pathogen antigen’s fixed to solid support  Patient’s serum incubated. Antibodies for pathogen will bind to antigen, those that don’t will be washed away  Enzyme-labeled anti-antibodies bind to patient antibodies  When enzyme binds catalyzes production of visibly colored compounds  Measure the amount of bound enzyme based on color  Second antibody may be made specific for IgG or IgM or other immunoglobulins TEST YOUR KNOWLEDGE #1  You are a Family Medicine Physician.Your healthy, 30-year-old, biologically male patient presents to your office complaining of severe gastrointestinal pain, nausea, vomiting, and diarrhea. After talking to your patient about signs & symptoms, if he knows anyone currently sick with norovirus, and things he ate in the last 24-48 hours, you begin to become suspicious that the bagged salad your patient ate the night before might be the culprit as there is a salad recall currently in effect. If you were doing a stool culture, which agar would you use to support your theory that he has an E.coli infection? (and why, so we can discuss in class) A. Bile Esculin Agar B. EMB agar C. Nutrient broth agar D. MacConkey agar  4. DIAGNOSING INFECTION BY DETECTING PATHOGEN MACROMOLECULES (& GENETIC TESTING) A. Antigen detection tests B. Nucleic Acid-Based Diagnosis of Infection C. Microarrays D. Next-Gen Sequencing  A. ANTIGEN DETECTION TESTS  Like reverse serologic tests  Specific antibodies used to capture antigen from a patient’s sample  Ex. Simple agglutination assay  Negative- no antigen binds to antibodies  Positive- antigen binds causing clumping  Prozone- too much antigen than antibody, no clumping occurs, false negative  To fix: dilute & it becomes positive Latex agglutination test- uses antibody-coated latex beads to detect capsular material  A. ANTIGEN DETECTION TESTS- ELISA & EIA  Enzyme-linked immunosorbent assay (ELISA)- quantify antigen in solution  Enzyme immunoassays (EIA)- used to visualize and quantify antigens  Patient sample co-incubated with enzyme labeled antigen. Will compete with binding to antibody on solid support  No antigen= no decrease in color  Antigen in patient’s sample= decrease in color TEST YOUR KNOWLEDGE #2  You perform antimicrobial sensitivity testing on a patient’s sample. These are the results. Which antibiotic(s) would be the most effective to prescribe the patient? (Just give me the letter(s)) B. NUCLEIC ACID-BASED DIAGNOSIS OF INFECTION  DNA is two strands. When you heat it, the strands separate  When the temperature lowers (annealing), they reconnect “hybridization” (they HAVE to be complementary to each other)  Using a DNA probe (short single-stranded DNA sequence) you can hybridize it to a “target” sequence  DNA probe test was first nucleic acid-based test used  In situ hybridization can be done in tissue  C. NUCLEIC ACID AMPLIFICATION- PREMISE BEHIND PCR  Sometimes you don’t have enough of the specific nucleic acid in a sample to use direct detection with DNA probe to so need to amplify uses the concepts previously discussed Amplified sequences = amplicons  POLYMERASE CHAIN REACTION (PCR)  Real-time PCR (aka quantitative PCR aka qPCR) (NOT “RT- PCR” which is reverse-transcriptase PCR)  Targeted for specific segment of DNA bound by two primers  Commercially available assays available to detect different bacteria & viruses in patient samples (time saving)  Can use fluorescent-labeled probe  Combines steps of amplification & amplicon analysis  Helps quantify the target nucleic acid sequence by measuring # of cycles required to reach threshold of fluorescent detection  Fun fact: a “bad” PCR was used for reasonable doubt in OJ Simpson case TO PCR OR NOT TO PCR… NUCLEIC ACID BASED DIAGNOSIS OF INFECTION  PCR DEBATE  In med school, the basic scientists (PhDs) will tell you to perform PCRs, but the clinicians will tell you to treat  This is nuanced & depends on context  E.g., if a patient is in shock & dying of a bacterial infection, you don’t have time to wait for a PCR, you would treat with broad-spectrum  However, if a patient is presenting with a new viral infection and you need to know what it is, or if a patient is not responding to treatment of a disease PCR would be the correct answer choice to determine what it is  In an ideal world, you could start broad spectrum treatment, while sending off PCR & switch patient to more specific treatment once results are in. Boards questions don’t always allow that option, so read carefully for the context! PROS & CONS OF PCR VS. SEROLOGY VS. ANTIGEN C. MICROARRAYS  Since bacteria have conserved sequences, you have the potential to amplify products from any bacterial species  You could then hybridize to the microarray containing sequences from hundreds of bacterial species  Can help you determine which one (or ones) is (are) present in patient sample  D. NEXT-GEN SEQUENCING  Next generation sequencing (NGS) determines the DNA sequence of a complete bacterial genome in a single sequence run, and from these data, information on resistance and virulence, as well as information for typing is obtained, useful for outbreak investigation TEST YOUR KNOWLEDGE #3  Which of these latex agglutination tests are positive or negative?  ALSO A SCIENTIST Jane Hinton, DVM (1919-2003) -DVM from University of Pennsylvania  One of the first two African-American women to earn a DVM  Granddaughter of slaves  Her father Dr. William Augustus Hinton opened the first “Medical Laboratory Techniques” courses open to women (“not a woman’s job”)  Co-developed Mueller-Hinton agar used to isolate Neisseria bacteria.  Mueller-Hinton agar is the gold standard for antibiotic testing Prevention Strategies & Vaccines  WHY DO WE CARE? PREVENTION STRATEGIES FOR INFECTIOUS DISEASE  Last week we learned about the two components of the immune system, innate & adaptive, which helps our body fight infection.  Today we’ll be discussing how to PREVENT infectious diseases SURVIVAL OF HUMAN POPULATIONS BY YEAR  CLASS OBJECTIVES  Define vocabulary words  To be able to educate yourself and your patients on how to prevent infections using the below learning objectives:  Compare & contrast contagious and communicable  Differentiate endemic, epidemic, and pandemic  Elaborate on and be able to identify the types of transmission and an example of each  List and give examples of the Standard Precautions for clinical settings  Describe which standard precautions for clinical settings (& PPE) would be best for different types of threats, e.g. blood-borne, vs. inhalation/respiratory, etc.  Define the following terms and give three examples of each: sterilization, disinfection, and antisepsis  Define the three levels of disinfection and give examples of each. When would each type of disinfectant be used?  Communicable infection- one that is spread from host to host Contagious means that the infection is easily transmitted Reservoir- the living or non- living normal residence of an infectious agent. Zoonotic diseases are those with infectious agents that reside and replicate within non-human animals Vectors- living creatures that transmit a pathogen to humans; i.e. mosquitoes Host- organism that provides nourishment and/or shelter to the agent  DISEASE PREVALENCE Endemic- presence of infection is maintained at constant level within area or group aka “baseline” Epidemic- rise in disease cases above area/group “baseline” Pandemic- epidemic spread across multiple countries/continents  TYPES OF TRANSMISSION A. General Transmission 1. Abiotic environmental factors  Fomites are inanimate objects that transmit pathogens  Soil & water harbor pathogens 2. Animal/Insect Vectors  Arthropods  Other animals including farm animals B. Human-to-Human Transmission 1. Vertical transmission- infectious agents are passed from mother-to-offspring during pregnancy (transplacental transmission), childbirth, or breastfeeding i.e. ZIKA 2. Horizontal transmission- other human-human transmission  Direct contact- i.e. HIV, Herpes  Indirect contact- i.e. norovirus  Droplets (i.e. bodily fluids)- i.e. HIV  Respiratory/Airborne- i.e. influenza  Fecal-oral- i.e. norovirus  HOW TO PREVENT INFECTIONS: STANDARD CLINICAL PRECAUTIONS  Basic guidelines established by the U.S. Center for Disease Control: 1. Good hand hygiene includes washing with soap and water or hand rubbing with alcohol-based products before and after direct contact with patients, devices, and other objects 2. Personal protective equipment (PPE) includes gloves, masks, and gowns that create a barrier between the medical professional and infected individuals or contaminated objects 3. Respiratory hygiene and cough etiquette means that individuals, including patients, should cover their mouths when coughing or sneezing 4. Proper patient placement requires that patients with infectious diseases should be separated from non- infected patients 5. Maintenance of a clean environment means that the facility and commonly used objects are routinely cleaned and disinfected 6. Careful handling of laundry calls for precautions be used to protect mucous membranes from exposure to infectious agents 7. Safe injection practices include careful handling and cleaning of injection paraphernalia; syringes and needles should never be re-used 8. Sharps safety ensures that needles and other sharp tools, such as scalpels, are used and disposed of properly  >1,000 healthcare professionals are injured by needles or other sharp devices every day GOOD HYGIENE: PRIMARY WAY TO PREVENT INFECTIOUS DISEASES  How to properly wash your hands SCIENCE WITH KENNEN: WEAR YOUR MASKS Check him out on IG, Youtube, Facebook: @ScienceWithKennen PATHOGEN ELIMINATION: ANTISEPTICS VS. DISINFECTANTS VS. STERILIZATION  ANTISEPSIS  Antisepsis: Use of chemical agents on skin or other living tissue to inhibit or eliminate microbes; no sporicidal action is implied  Alcohols- all groups of organisms except spores  Iodophors- similar to alcohol, but more toxic to skin  Chlorhexidine- broad antimicrobial (kills at a slower rate than alcohol)  Parachlorometaxylenol (PCMX)- primarily gram+ bacteria  Triclosan- bacteria, not safe for humans?  DISINFECTION  Disinfection: Use of physical procedures or chemical agents to destroy most microbial forms; bacterial spores & other relatively resistant organisms (e.g., mycobacteria, viruses, fungi) may remain viable  Level used is determined by relative risk surfaces pose as reservoir for pathogens  Low-level disinfectants- used to treat noncritical instruments & devices (e.g. blood pressure cuffs, electrocardiogram electrodes, & stethoscope)  Ex. i.e., quaternary ammonium compounds  Intermediate-level disinfectants- used to clean surfaces or instruments on which contamination with bacterial spores & other highly resilient organisms is unlikely (e.g. semicritical instruments & devices like laryngoscopes, vaginal specula, anesthesia breathing circuits, etc.  Ex. alcohols, iodophor compounds, & phenolic compounds  High-level disinfectants- used for items involved with invasive procedures that cannot withstand sterilization procedures (e.g., certain types of endoscopes & surgical instruments with plastic or other components that cannot be autoclaved)  Ex. Moist heat & use of liquids such as glutaraldehyde, hydrogen peroxide, peracetic acid, & chlorine compounds STERILIZATION  Sterilization- total destruction of all microbes, including the more resilient forms such as bacterial spores, mycobacteria, nonenveloped (nonlipid) viruses, & fungi using physical, gas vapor, or chemical sterilants  Steam under pressure- widely used, inexpensive, nontoxic, reliable (autoclave)  Ethylene oxide gas- sterilize temp or pressure sensitive items  Hydrogen peroxide vapors- sterilization of instruments  Chemical sterilants- peracetic acid & glutaraldehyde GERMICIDAL PROPERTIES OF DISINFECTANTS AND ANTISEPTIC AGENTS Germicide: Chemical agent capable of killing microbes; includes virucide, bactericide, sporicide, tuberculocide, and fungicide ALSO A SCIENTIST Michel Yao, PhD -MSc, Health- Université de Montréal -PhD, Public Health- Université de Montréal  WHO’s Program Manager for Emergency Response for Africa  Also in Netflix’s “Pandemic: How to Prevent an Outbreak”  https://www.facebook.com/WHOAFRO/videos/dr-michel- yao-world-health-organization-who-afro-emergency- operations-manager-ou/193232565084897/  @drmichelyao1 on Twitter WHY YOU SHOULD CARE CLASS OBJECTIVES  Understand why vaccines are important  Compare & contrast routine, required, & elective vaccines  Describe the origination of variolation & vaccination  Describe the different type of vaccines  List the characteristics of vaccines  Define adjuvants and provide an example  Be able to have a discussion with an anti-vax or on-the-fence patient/patient's parent about vaccination, why it's important, and debunk some common vaccine myths  Learn where to find out more information on vaccines if you don’t remember, or want to learn more VACCINATIONS ARE ESSENTIAL TO AVOID GETTING SICK HISTORY OF VACCINATION  Individuals who survived smallpox, plague, & cholera rarely contracted the disease again, even when surrounded by others suffering from that particular disease  Among ancient cultures, Egyptians & Chinese exposed individuals to powders formed from crusts & scales of pockmarks taken from individuals recovering from smallpox (Variola major virus)  Individuals developed either mild forms of the disease or no apparent disease at all  https://ourworldindata.org/vaccination  VARIOLATION VS.VACCINATION  Edward Jenner (1796)- intentional inoculation with material from individuals with cowpox (Variola minor, a related virus that infects cattle, but causes mild disease in humans) protected against smallpox  Variolation- deliberate inoculation of an uninfected person with smallpox virus (e.g. contact with pustular matter) that was widely practiced before era of vaccination as prophylaxis against severe form of smallpox  “cowpox inoculation” or “vaccine inoculation” (from Latin vacca = cow)  Vaccination- The act of introducing a vaccine into the body to produce immunity to a specific disease  HOW VACCINES WORK  HOW VACCINES WORK: https://www.tiktok.com/@hotvickkrishna/video/6937457241968643334?i s_from_webapp=v1&item_id=6937457241968643334&lang=en https://www.tiktok.com/@hotvickkrishna/video/6946300405756349702?i s_from_webapp=v1&item_id=6946300405756349702&lang=en  VACCINES CAN BE PREPARED FROM VARIOUS MATERIALS DERIVED FROM PATHOGENIC ORGANISMS  Live-Attenuated vaccines- based on living organisms but had virulence & ability to replicate reduced by treatment with heat, chemicals, etc. Typically cause only subclinical or mild forms of disease, but do carry possibility that mutation might enable organisms to revert to wild type. Booster shots not usually needed.  Ex. MMR, smallpox, chickenpox, yellow fever  Inactivated (killed) vaccines- organisms that are dead because of treatment with physical or chemical agents, or inactivated toxins (toxoids- diphtheria & tetanus vax). Difficult to guarantee that every organism in a preparation is dead. Incapable of infection, replication, or function but still provokes immunity. Booster shots sometimes needed.  Ex. Polio shot, Hep A, Flu  Subunit, recombinant, polysaccharide, and conjugate vaccines- use specific pieces of the germ—like its protein, sugar, or capsid (a casing around the virus). Some can infect host cells but cannot induce disease; Booster shots sometimes needed; adjuvants often used  Ex. Hib, Hep B, HPV, Shingles  Ex. J&J Covid- uses a recombinant vax model- weakened live adenovirus with spike protein  VACCINES CAN BE PREPARED FROM VARIOUS MATERIALS DERIVED FROM PATHOGENIC ORGANISMS  DNA vaccines- naked DNA extracted from pathogen & engineered to remove some of genes critical to development of disease. Host cells to take up DNA & express the pathogen gene products. Typically lasts longer than other methods where vaccine is rapidly eliminated from host  Ex. India’s Covid vax, no DNA vaccines approved for humans in US (yet)  RNA vaccines- RNA vaccines work by introducing an mRNA sequence (the molecule which tells cells what to build) which is coded for a disease specific antigen; faster & cheaper to produce than “traditional” vaccines  Ex. Pfizer & Moderna Covid Vax  Best immune responses: Live-attenuated vaccines → inactivated vaccines → everything else  Replicating organisms= good immune responses → safety of a vaccine may be inversely proportional to its effectiveness  CHARACTERISTICS OF VACCINES  Vaccines must fulfill several criteria to be effective in protecting large numbers of individuals: 1. Effective protection against intended pathogen must occur without significant danger of actually causing the disease or of producing severe side effects 2. Protection that is provided must be long lasting. 3. Vaccine must induce immune responses most effective against intended pathogen across a broad range of individuals 4. Neutralizing antibodies must be stimulated in order to minimize reinfection 5. Vaccine must be economically feasible to produce 6. Vaccine must be suitably stable for storage, transport, & use WHY BOOSTERS?!  Maybe too specific, but I've been wondering for awhile why COVID boosters were recommended so close to the original vaccination date when other vaccines, like Tdap, last a very long time before the booster is required. If it was a new vaccine like for that of flu, I'd understand, but a "booster" is there to help the body remember the same thing, right? Is the body just stupider when it comes to COVID?  https://www.tiktok.com/@hotvickkrishna/video/7039798030660275462?is_from_we bapp=v1&item_id=7039798030660275462&lang=en DID WE RUSH THE COVID VACCINE?  CAN VACCINES CAUSE GENETIC MUTATIONS?  No, due to the Central Dogma of Molecular Biology  Unlike vaccines using weakened pathogens, DNA & RNA vaccines only carry the information needed to produce one or more bacterial or viral proteins and cannot generate the entire pathogen  https://www.chop.edu/centers- programs/vaccine-education- center/video/can-mrna-vaccines-alter-a- persons-dna  Not on the test, but very helpful: https://www.medicalnewstoday.com/art icles/dna-vs-mrna-vaccines-similarities- and-differences  HOW DO TESTING AND CLINICAL TRIAL PROCESSES WORK?  HOW DO WE ADDRESS THE ARGUMENT THAT VACCINES AREN'T TESTED THE WAY THEY ARE ADMINISTERED SINCE MULTIPLE VACCINES ARE OFTEN GIVEN AT THE SAME TIME?  They ARE tested (and together) ☺  Rotarix was tested with Pediarix (DTaP-HepB-IPV), Prevnar, and Hib  Prevnar 13 was tested with DTaP, IPV, hepatitis B and Hib  Prevnar 13 was tested with MMR, Varicella, and hepatitis A  MenC with DTaP-IPV-HepB-Hib  MenC with MMR  MMR and Varicella with Hib, Hepatitis B, and DTaP  Hepatitis A and hepatitis B with either MMR or DTaP-IPV-Hib  Flumist with MMR and Varicella  Kinrix (DTaP-IPV) with MMR and Varicella  HPV9 with Tdap and Meningococcal vaccines  Tdap with influenza vaccine  Meningococcal vaccine with influenza vaccine  Source with sources: https://vaxopedia.org/2017/08/20/are-vaccines-tested-together/  GREAT site: https://vaxopedia.org/2017/04/25/50-ways-to-get-educated-about-vaccines/  BUT IF I’M HEALTHY WHY SHOULD I GET A VACCINE? HERD IMMUNITY  Can provide excellent protection to a population, even if every individual is not vaccinated  Herd immunity- resistance to spread of an infectious disease within a population due high levels of pre-existing immunity (previous infection OR vaccination)  With ↑ vaccination, chances of an infectious agent “finding” an unprotected individual becomes ↓ = population resistant as a whole  HOWEVER  Infection can still spread in unvaccinated individuals  New mutant forms might arise that could evade the immune response & produce disease in vaccinated individuals as well  “Breakthrough strains”  BREAKTHROUGH STRAINS  https://www.youtube.com/watch?v=zcbPV2B8FPM SO HOW DO WE KNOW IF A VACCINE IS EFFECTIVE?  Vaccine effectiveness (VE) depends on:  1) characteristics of the person being vaccinated (such as their age and health)  2) the similarity or “match” between the virus the vaccine is designed to protect against and the viruses spreading in the community  WHAT IS AN ADJUVANT?  An adjuvant is an ingredient used in some vaccines that helps create a stronger immune response in people receiving the vaccine  Help produce a stronger immune response  However more likely to experience “side effects” like injection site soreness, redness, & swelling  Some vaccine components themselves can serve as adjuvants  Ex. Pertussis component (from Bordetella pertussis) in DTP (Diphtheria-Tetanus-Pertussis) vaccine  Other adjuvants include alum  Aluminum salts (aluminum hydroxide, aluminum phosphate, and aluminum potassium sulfate)  Safety review of aluminum salt pharmacokinetics in vaccines: https://pubmed.ncbi.nlm.nih.gov/22001122/  https://www.cdc.gov/vaccinesafety/concerns/adjuvants.html  DID YOU KNOW…. THERE IS MORE ALUMINUM IN BREAST MILK (7 MG), FORMULA (38MG), & SOY FORMULA (117 MG) THAN IN ALL THE VACCINES ADMINISTERED IN THE FIRST 6 MONTHS OF LIFE (4.4 MG) HTTPS://WWW.CHOP.EDU/CENTERS-PROGRAMS/VACCINE-EDUCATION-CENTER/VACCINE- INGREDIENTS/ALUMINUM  WHAT ELSE IS IN VACCINES?  Thimerosal??? (ethylmercury, NOT to be confused with methylmercury)- Preservative  Methylmercury is the dangerous stuff found in fish. Can be toxic.  Ethylmercury is structurally different, cleared from the body quickly, and shown to be safe.  Precautionarily removed/reduced from vaccines in 1999 as a show of good will by American Academy of Pediatrics  https://www.cdc.gov/vaccinesafety/concerns/thimerosal/inde x.html  Summary of all the studies: https://www.cdc.gov/vaccinesafety/pdf/cdcstudiesonvaccines andautism.pdf FORMALDEHYDE? (PRESERVATIVE)  WHAT ABOUT ABORTED FETAL TISSUE?  Viruses need cells to grow (remember, they don’t have their own machinery like pro & eukaryotes)  VZV, Rubella, Hep A, & Rabies grown in fetal embryo fibroblast cells  These fetal embryo fibroblast cells came from elective termination of pregnancy in the 1960s (WI-38 & MRC-5)  However, because of cell culture & storage, the same cell lines have been used forever  VACCINES DO NOT CONTAIN THESE CELLS OR THEIR DNA DO VACCINES CAUSE AUTISM? RACIAL INEQUALITIES IN VACCINATION RATES https://covidtracking.com/race  FOLLOW UP RESOURCES  AMAZING INFOGRAPHICS- @niniandthebrain on IG https://www.instagram.com/niniandthebrain/?hl=en, @virus.vs.labcoat on IG https://www.instagram.com/virus.vs.labcoat/?hl=en @deplatformdisease on IG https://www.instagram.com/deplatformdisease/?hl=en  @jessicamalatyrivera on IG https://www.instagram.com/jessicamalatyrivera/?hl=en  Reels & TikToks @christinaaaaaaanp on IG & TikTok  Covid Tracking Project https://covidtracking.com/  CDC Overview, History, and How the Safety Process Works: https://www.cdc.gov/vaccinesafety/ensuringsafety/history/index.html  Childhood Vaccine info: https://www.cdc.gov/vaccines/parents/index.html  2020 Easy to Read Vax Guide: https://www.cdc.gov/vaccines/schedules/easy-to-read/child-easyread.html  En espanol: https://www.cdc.gov/vaccines/schedules/easy-to-read/child-easyread-sp.html  Vaxopedia (wonderful!): https://vaxopedia.org/  Vaccine myths debunked: https://vaxopedia.org/tag/vaccine-myths/  Children’s Hospital of Pennsylvania: https://www.chop.edu/centers-programs/vaccine-education-center  History of Vaccines: https://www.historyofvaccines.org/content/blog/vaccine-randomized-clinical-trials  ALSO A SCIENTIST  Dr. Kizzmekia Corbett, PhD Assistant Professor of Immunology & Infectious Diseases, Harvard T.H. Chan School of Public Health  The vaccine concept incorporated in mRNA-1273 was designed by Corbett’s team from viral sequence data and rapidly deployed to industry partner, Moderna, Inc. only 66 days after viral sequence release https://asm.org/Biographies/Kizzmekia-S-Corbett,-Ph-D https://www.hsph.harvard.edu/news/press-releases/kizzmekia- corbett-joins-harvard-chan-school/