Wk1 plagues pandemics

for me

Epidemiology

Finding the causes of diseases, including infectious and non-infectious diseases.

Miasma Theory

The old idea that disease was caused by “bad air.”

Germ Theory

Idea that microbes cause disease

Epidemic

An outbreak of infectious disease that then subsides

Epidemic

An outbreak of infectious disease within a community or region

Big 3

HIV, TB, malaria

Innate immunity

Limits the spread of pathogens during initial infection, activates adaptive immune system

Adaptive Immunity

Can eliminate specific pathogens, creates memory for faster responses during future infections

DNA

ATGC, preferred genetic material

DNA base pairing

AT, GC

RNA

AUGC, used in many viruses

Central dogma

DNA → RNA → Protein

Triplet code

3 nucleotides = 1 amino acid

Retroviruses

Makes DNA from RNA template through reverse transcription; HIV

RNA viruses

Makes direct copies of RNA through RNA replication

Prions

Proteins capable of replicating without DNA or RNA`

Gene

segment of DNA/RNA that gives rise to protein

Genome

All nucleic acids passed from parent to offspring, includes DNA that isn’t genes

Virus

Infectious pathogen (HIV)

Bacterium

Prokaryotic pathogen (TB)

Protozoan

Eukaryotic pathogen (malaria)

Morbidity

Illness/complications caused by disease, ex. parasitic worms may cause morbidity w/o directly causing death

Phagocytes

WBC that “eat” pathogens/material through phagocytosis

Macrophage

Performs phagocytosis, presents antigens, removes old/dying cells, repairs wounds, stimulates adaptive immunity, detects pathogens, and orchestrates inflammation

Macrophage killing

Kill when activated by cytokines

Dendritic cell (DC)

Takes up antigens @ peripheral infection sites, presents them in lymph nodes, helps initiate adaptive immunity

Neutrophil

Major/common phagocyte responsible for killing bacteriaNeut

Neutrophil granules

contain toxic proteins & enzymes that kill bacteria

Neutrophil Disadvantage

Toxic contents can cause substantial damage to surrounding healthy tissue

Neutrophil Lifespan

Short-lived, rapidly repleted from bone marrow

Lysosome

Contains enzymes that digest engulfed material

B cell

Only cell type capable of producing antibodies

Antibody

Protein produced by B cells that binds to an antigen

FAB region

Variable region of an antibody that specifically binds an antigen

Fc region

Constant region of an antibody that determines its isotype/functions

Antibody isotypes

IgM, IgG, IgA, IgE

Antibody diversity

10^11 different antibodies

B Cell specificity

Each B cell creates one kind of antibody

Neutralization

antibodies bind pathogens/toxins & block their function

Opsonization

Antibodies make pathogens easier for phagocytes to engulfC

omplement

Can promote opsonization, phagocytosis, or lysis

Antibody-dependent cellular cytotoxicity

Antibodies coat a target cell & recruit cytotoxic(CT) WBCs to destroy it

Cytotoxic T Cell

Kills infected cells, especially virally infected cellsCD

CD8+ T cell

Cytotoxic T cell that kills phagocytes

CD4+/T helper cells

produces cytokines & regulates adaptive immune responses

T cell receptor (TCR)

Recognizes antigen when presented by MHC

major histocompatibility complex (MHC)

displays pathogen fragments on host cell surfaces

Professional antigen-presenting cells

dendritic cells, B cells, macrophages

DC movement

picks up pathogens @ infection sites → brings to regional lymph nodes/spleen

CTL recognition

when a cytotoxic T cell’s TCR recognizes antigen on MHC, it kills the infected cell

CTL specificity

Provides highly specific killing without widespread non-specific damage

Active immunization

vaccination that establishes immune memoryP

Passive immunization

transfer of antibodies, does not establish immune memory

Passive immunity duration

protection lasts as long as antibodies remain, 3-6 months

Preventetive vaccine

given to healthy/naive individuals to prevent disease from primary infection

Therapeutic vaccine

Given to infected individuals to prevent/reduce disease or stimulate anti-tumor response

vaccine goal

establish memory B/T cells to provide protection from future infection

immunodominance

identifying key antigens that generate strong T/Bcell responses

Vaccine challenge

Must avoid excessive immune pathology(when body reacts too strongly), overactive immune response can cause disease

Route of immunization

Most vaccines are intramuscular/subcutaneous, some can be oral (rotavirus & polio)

Adjuvant

Crucial in non-replicating vaccines to enhance immunogenicity

Adjuvant mechanism

Activates TLRs, promotes inflammation, activate antigen-presenting cells, increases CD4 T cell & antibody responses

Antigenic Variation

Changes in pathogen antigens, caused by high viral mutation rates

Attenuated/live vaccine

Weakened pathogen with a reduced ability to cause disease (OPV, MMMR, VZV)

Advantage: low dose, no adjuvant, authentic antigen presentation, effective CTL response
Disadvantage: Possible reversal of virulence

Inactivated vaccine

Killed/inactivated organism/toxin (influenza, hep A, pertussis, IPV, tetanus & diphtheria)

advantage: cannot be reverted to virulence
disadvantage: doesn’t replicate & provides poorer antigen presentation for CTL

Live vector vaccine

Inserts genes from a pathogen into a well-categorized vaccine vector (vaccinia, adenovirus, salmonella, ebola..)

advantage: self-replicating, may not require adjuvant
disadvantage: possible pathogenesis

Recombinant protein vaccine

Uses immunogenic proteins (envelope/outer-membrane proteins) produced in large quantities (Hep B, HPV, malaria)

Advantages: safe & relatively easy to produce
Disadvantages: usually requires adjuvants/boosters, may not produce long-term memory

SARS-CoV-2 vaccine target

spike protein ← major target of neutralizing antibodies

mRNA vaccine

uses lipid nanoparticles to deliver mRNA in to host cells, allowing cells to produce the target protein

advantage: fast production & easy adaptation to new pathogens
disadvantage: must be encapsulated in lipids/sugars

AstraZeneca vaccine

viral-vector vaccine; 79% efficacy against symptomatic COVID 19

Johnson & Johnson vaccine

Targets adenovirus/spike, 66-72% efficacy

Sputnik V

Adenovirus causing 2 different adenovirus for priming & boosting, 91.7% efficacy

Sinovac/CoronaVac

Inactivated vaccine, can be stored in refrigeration