Exam 4 Flashcards
Mutualism
A reciprocal benefit accrues to both partners
Mutualism example
Buchnera aphidicola and aphids
what are Buchnera aphidicola?
- Gram negative
- lives in the aphid
- transmitted vertically from mother to daughter
Buchnera aphidicola are obligate __________
Mutualists
What does the aphid do for Buchnera?
Aphid provides Buchnera with amino acids that Buchnera cannot make
What does Buchnera do for the aphid?
Buchnera must synthesize and provide Trp for the aphid since aphids cannot make Trp
What is attenuation?
A proposed mechanism of control in some bacterial operon which results in premature termination of transcription
-based on the fact that, in bacteria, transcription and translation proceed simultaneously
In Attenuation, if Region 2 of the RNA pairs with Region 3 of the RNA..
- nonterminating stem loop
- Transcription continues
In Attenuation, if region 3 of the RNA pairs with Region 4 of the RNA…
- terminating stem loop forms
- Transcription terminated
In Attenuation, the translation of which peptide affects which region pairs?
The leader peptide
Cooperation
A reciprocal benefit accrues to both partners
Aka if we inactivate B, A is going to okay, but A prefers having B
Commensalism
One symbiont (the commensal) benefits while the other (host) isn’t harmed or helped
Example of Commensalism
Staphylococcus epidermidis
What is Staphlococcus epidermidis?
Commonly found on human skin and consumes human waste while normally having no impact on human health
Predation
One organism preys on another
What is an example of a predator in predation?
Bdellovibrio
What is Bdellovibrio?
Gram negative bacteria that preys on other gram negative bacteria
Parasitism
The parasite benefits while the host is usually harmed
What is the perfect example of parasitism?
Infectious diseases
Amensalism
The adverse effect that one organism as on another
What type of process is Amensalism?
a unidirectional process where the presence of A inhibits B
What are two examples of Amensalism?
- Penicillin
- Streptomyces spp.
competition
Two organisms try to acquire the same resources (location or nutrient)
What are the two outcomes of Competition?
- One outcompetes the other for the site’s resources
- Both coexist at lower levels because they share the same limiting resource
Human microbiota
Microbes that live in or on humans
What type of relationship do human microbiota typically have with humans?
Commensal or mutualistic
How many organisms make up the human microbiota?
Mouth: 10^10 (0.1% total
Skin: 10^12 (1% total)
Intestines: 10^14 (99% total)
Are gut specific microbiota mainly anaerobic or aerobic?
Aerobic
What is biofilm?
Slime-encased aggregation of bacteria that is composed of protein, polysaccharide, and extracellular DNA
CAZymes
Enzymes that break down carbohydrates
Do humans have CAZymes?
No
What does the human microbiota do?
- provides nutrients for the host
- protects her body from invasion of harmful bacteria
Pathogen
Any disease producing microorganism
Clostridium difficile loves what kind of person?
Patients that are undergoing microbial treatment
What is C. Difficile?
A gram positive, spore-forming anaerobe that colonizes people that have been treated with antibiotics
Where experiences the largest issue with C. Difficile?
Hospitals and healthcare settings
What are the two layers of Spore peptidoglycan?
- A small inner layer of peptidoglycan that can make up the new cell wall under germination
- a larger layer of specialized peptidoglycan (cortex) that is composed of NAG & NAM
what are current treatment options for C. Difficile?
- Vanomycin
- Difficid (fidaxomicin)
- Zinplava (Bezlotoxumab)
What is the most highly organized lymphoid organ?
The spleen
What does the spleen do?
- filters blood
- antigen production
- present antigens to B and T cells
What is the most highly organized lymphoid tissue?
Lymph nodes
What do lymph nodes do?
- filter lymph
- B cells differentiate into memory and plasma cells within lymph nodes
What are other names for a nonspecific immune response?
- nonspecific resistance
- innate immunity
- natural immunity
What are other names for specific immune response?
- acquired immunity
- adaptive immunity
- specific immunity
What are cationic peptides?
Highly conserves peptides that have 3 classes related to their ability to damage bacterial plasma membranes
Cationic Peptide
First class: Linear
Alpha-helical peptides that lack cysteine amino acid residues
What is an example of a first class cationic peptide and where is it produced?
Cathelicidin and it is produced by a variety of cells
Cationic peptides
Second Class: Defensins
- peptides that are open-ended, rich in arginine and cysteine, and disulfide linked
Where are Defensins found?
in neutrophils, intestinal Paneth cells, and intestinal and respiratory epithelial cells
Cationic Peptides
Third class: Larger peptides that are enriched for specific amino acids and exhibit regular structural repeats
examples
histatin, present in human saliva and has anti-fungal activity
What are Bacteriocins?
peptides produced by normal microbiota that are lethal to related species and are produced by both gram-positive and gram-negative cells
What does opsonin do for the efficiency of phagocytosis
it increases the efficiency
At what point do the classical pathway, MB-Lectin pathway, and Alternative converge?
C3 convertase
What are the four families of cytokines?
chemokines, hematopoietins, interleukins, and tumor necrosis factor (TNF) family
What do Chemokines do?
Stimulate cell migration and attract phagocytic cells and lymphocytes
What do Hematopoietins do?
Stimulate and regulate the growth and differentiation in the blood cell formation
What do Interleukins do?
Regulate the growth and differentiation of other cells, primarily lymphocytes and hematopoietic stem cells
What can Tumor necrosis factor induce?
apoptosis
What are irregularly-shaped nuclei with two to five lobes?
Granulocytes
What are three types of granulocytes?
Basophils, eosinophils, and neutrophils
What are derived from monocytes, but are larger?
Macrophages
What is the function of dendritic cells?
Phagocytosis and antigens processing -> foreign antigens on their surfaces (antigen presentation to T and B cells)
- Create an adaptive immune response
What type of granulocytes have the ability to explode?
Neutrophiles
What are the two mechanisms for recognition of microbe by phagocyte?
1) Opsonin-independent (nonosponic) recognition
2) Opsonin-dependent (opsonic) recognition
does opsonin-independent or opsonin-dependent work via pattern recognition receptors?
Opsonin-independent
Which one is stronger and very aggressive? opsonin-independent or opsonin-depended recognition?
Opsonin-dependent (opsonic)
What type of pathogen recognition is characterized by components that are non-specifically recognized to activate phagocytes?
Opsonic-independent
Which pathogens mechanism is characterized by the binding of opsonins to the phagocyte?
opsonin-dependent
What are the 4 main forms of opsonin-independent recognition?
Recognition by:
- lectin-carbohydrate interactions
- protein-protein interactions
- hydrophobic interactions
- pattern recognition receptors
In what organism are toll-like receptors identified?
The Drosphila melongaster (fruit fly)
___-like receptors are intracellular proteins tat act as PCR
NOD
Where does the pattern of the C-reactive protein (soluble) target?
Gram-positive cell walls
What are characteristics of adaptive immunity?
- discrimination between self and non-self
- diversity
- specificity
- memory
Antigens definition
Self and non-self substances that elicit an immune response and react with the products of that response
Epitope definition
Regions/sites of the antigens that bind to a specific antibody or T-cell receptor
Where do epitopes reside?
Within the antigen
It is acquired through the normal life experiences of a human and is not induced through medical means
Natural immunity
It is the consequence of a person developing his or her own immune response to a microbe
Active immunity
It is the consequence of one person receiving preformed immunity made by another person
Passive immunity
Is that produced purposefully through medical procedures (also called immunization)
Artificial immunity
What is an example of natural active immunity?
Infection
What is an example of natural passive immunity?
Maternal antibody
What is an example of artificial active immunity?
Vaccination
What is an example of artificial passive immunity?
Immune globulin therapy
What are antigens?
antibody generators that induce immune responses
What do antibodies bind to?
Antibodies bind to specific antigens, inactivating or eliminating them
Where do T-cell originate? Where do they mature?
CD34+ stem cells in the bone marrow; in the thymus
How many classes are there in the Major Histocompatibility complex (MHC)?
Three
MHC Class 1 can be found on ____ nucleated cells
All
MHC class 2 cal be found on what?
Cells that process non self materials such as macrophages and dendritic cells
MHC class 3 secretes products that have what kind of function?
Immune functions
What presents endogenously-derived antigens to cytotoxic T-cells?
MHC class 1
What are MHC Class 2 produced by?
- macrophages
- dendritic cels
- B cells
- T cells
What MHC class is required for T cell communication?
MHC Class 2
What are three types of T-cells?
Helper T, cytotoxic T lymphocytes (CTL), and regulatory T cells
What are the 5 types of T-Helper cells activated by MHC Class 2?
TH0, TH1, TH2, TH17, and Treg
What is TH0?
An undifferentiated precursor of 1, 2, and 17
What is TH1?
Promotes CTL activity, mediate inflammation
What is TH17?
Found mainly in the skin/epithelium and responds to bacterial invaders
What is Treg?
Recognizes self antigens, It secretes IL-10 to inhibit TH1 and TH2 mediated inflammation
What do cytotoxic T cells do after they mature into CTL upon antigen recognition (MHC Class 1)?
- Kill the infected cell
- Perforin pathway
- Fas-FasL pathway
What stimulate stronger immune response than normal antigens by “tricking” T cells into activation although they have not been triggered by a specific antigen?
Superantigens
Do superantigens stimulate T cells to proliferate specifically or nonspecifically?
Nonspecifically
Superantigens stimulate the release of massive quantities of cytokines from T cells. What may this result in?
Circulatory shock and multiogan failure
Examples of superantigens
- staphlococca enterotoxin B
- Toxic Shock Syndrome Toxin
What kind of cells are antibody producing cells?
B-cells
Transmembrane antibodies are specific for how many antigens?
One
Where are antibodies found?
In blood serum, tissue fluids, and mucosal surfaces of vertebrate animals
What are the 5 classes of antibodies?
IgG, IgM, IgA, IgD, IgE
Which class of antibodies are the main ones that make up 70-80% of the total circulating antibodies?
IgG
What is the first antibody type to appear in primary immune response?
IgM
What type of antibody is found in the GI tract and is the major secretory antibody?
IgA
What is the minor circulating antibody, mostly associated with mature B cells?
IgD
Which antibody type facilitates parasite immunity?
IgE
What is an example of class switching?
Switching from IgM to IgG
What happens during splice-site variability?
Genes splice and resemble differently
What is somatic hypermutation?
The genes that code for antibodies are very prone to mutation
During splicing, the junction between the V, D, and J segments can be changed. This leads to changes in the ________ resulting in _____ ____ change.
Codons; amino acids
Are mutations of the DNA that underwent somatic hypermutation hereditary?
No, because the mutations occur only in the cell undergoing the mutation and does NOT happen in the germ line
how many antibodies do each B-cells make?
Just one
Staphylococcus aureus Protein A
- Virulence determinant
- specifically binds antibodies
- binds the Fc region
Fc domain on antibodies =
The heavy chin part that is constant on S. aureus
science that evaluated occurrence, determinants, distribution, and control of heath and disease in a defined human population
Epidemiology
Epidemiologist
One who practices epidemiology
Who is the father of epidemiology?
John snow
John Snow started the fecal fora route of infection after what investigation of his?
After his investigation of cholera deaths in London
What did Snow discover from his cholera investigation?
That the people who died from cholera all drank from the same water pump that had a sewage leak
Endemic disease
A disease that maintains a steady, low-level at a moderately regular interval
Endemic diseases are specific to what and experience what level of occurrence?
They are specific to that area and happen at a high rate of occurrence
Incidence
Number of new cases
Outbreak
The sudden, unexpected occurrence of a disease
Attack Rate
Proportional number of cases that develop in a population exposed to the agent
Epidemic
An outbreak affecting many people at once
Index case
The first case in an epidemic
Pandemic
An increase in disease occurrence over a large area (worldwide)
Who was Typhoid Mary (Mary Mallon)?
An asymptomatic carrier of Typhoid that infected 24 people (2 died). She was a home cook that discovered she was shedding fecal salmonella.
Why did Typhoid Mary, and others with typhoid, still infect people after being deemed negative for the disease?
Because the disease lasts in the feces and the urine longer than it does in the blood (where it is tested from)
What two things significantly reduced the incidence of typhoid fever in 1906 and 1913, respectively?
filtration and chlorination
What are measures of an infectious disease reported as?
- Morbidity
- Mortality
- Prevalence
Morbidity Equation
Morbidity = (number of new cases during a specified time)/ (number of individuals in the population)
Prevalence equation
Prevalence = (total number of cases in the population)/ (total population)
Mortality equation
Mortality = (number of deaths due to the disease)/ (size of the total population with the same disease)
What are the two common types of epidemics?
1) Common source epidemic
2) propagated epidemic
Common source epidemic
Results from a single common contaminated source such as food
Propagated epidemic
Results from the introduction of a single infected individual into a susceptible population which is propagated to others
what is an example of a common-source epidemic?
Cholera
What is an example of host-to-host epidemic?
Influenza
When looking at a graph of Number of Cases Reported Each Day vs. Days, why does the trend go down?
Because immunity occurs over time and immunity blocks transmission
What is Herd Immunity?
Resistance of a population to infection and to spread of an infection organism
What can the Herd Immunity level be altered by?
- Introduction of new susceptible individuals into population
- By changes in pathogen antigenic shift and antigenic drift
Antigenic shift
A major change in antigenic character of pathogen
Antigenic drift
Smaller antigenic changes
Human Reservoirs
- infected humans are most significant reservoirs
- primarily of communicable diseases
(Reservoirs) Human Symptomatic Infections
Obvious source of infectious agents
(Reservoirs) Human asymptomatic carriers
Individual harbors pathogen with no ill effects
(Reservoirs) Non-Human animal : disease transmitted by non-human animal reservoir are termed zoonotic
Disease often more severe in humans than in normal animals
Example of a non-human Zoonotic disease?
Salmonella typhoid from chickens
Direct Contact
- requires physical contact to spread
- Hands are the primary source of contact
Indirect contact
- organism can live on a surface and then transfer to an individual
Droplet spread
- respiratory particles
- not only transmit the organism freely but some lie within the small droplets of liquid that come out such as a sneeze
What are the types of vaccines?
- whole-cell vaccines
- subunit vaccines
- DNA vaccines
What are the two types of whole-cell vaccines?
Inactivated and Attenuated
Salk’s vaccine, Inactivated Polio Vaccine (IPV), is inactivated by what?
Formalin
Who are the two people that founded the Polio vaccine?
Stalk and Sabin
What was Sabin’s vaccine like?
- A live attenuated vaccine
- an Oral vaccine
What is another name for subunit vaccines?
Acellular vaccines
What is the use of specific, purified macromolecules derived from pathogenic microbes that helps avoid some of the risks associated with whole-cell vaccines?
Acellular/Subunit vaccines
What are the three forms of subunit vaccines?
- Capsular polysaccharides
- recombinant surface antigens
- inactivated exotoxins (toxoids)
What are Recombinant-Vector Vaccines?
Pathogen genes that encode major antigens inserted into non-virulent viruses or bacteria which serve as vectors and express a certain gene
Released gene products (antigens) can elicit what?(Recombinant-Vector vaccines)
Cellular and humoral immunity
What is a DNA vaccine?
DNA directly introduced into host cell via air pressure or gene gun
when injected into muscle cells, DNA is taken into the nucleus and the pathogen’s DNA fragments is _____?
Expressed
What happens to RNA in RNA vaccines?
The RNA is translated in the cytoplasm to generate the required protein
What is an example of an RNA vaccine?
The Moderna Vaccine
What is the Moderna Vaccine?
A lipid-coated mRNA that fuses with host cells
What is Pfizer-BioNTech?
An mRNA vaccine similar to the Moderna vaccine
What is Johnson & Johnson?
Genetically-modified Adenoviral vector to deliver the antigen
What is AstraZeneca?
A dsDNA vaccine that encodes the spike protein antigen
What is Sputnik V?
Genetically modified Adenoviral vector to deliver the antigen?
What are Adjuvants?
An agent that stimulates the immune system and the immune response to aid in immunization
What are Adjuvants commonly combined with?
The vaccine antibody
What are examples of Intentional uses of biological agents in bioterrorism?
- 1984: salmonella typhrimurium
- 1996: Shigella dysentariae
- 2001 Bascillus anthracis
What is the most common Adjuvant used today? It was been researched for nearly 80 years and is deemed super safe.
Alum
What did Sir Alexander Fleming discover?
The Lysozyme and a halo of inhibition of Staphlococcus
What is considered the spearhead of antibiotics?
Penicillin
While Fleming observed Penicillin activity on a plate after Duchesne’s discovery, who was it that discovered the Effectiveness of Penicillin and won the Nobel prize for it?
Florey, Chain, and Heatley
Selective toxicity
The ability of a drug to kill or inhibit pathogen while damaging the host as little as possible
Therapeutic dose
Drug level required for clinical treatment
Toxic dose
Drug level at which drug becomes too toxic for patient
Therapeutic index
Ratio of toxic dose to therapeutic dose (the higher this value the more toxic it is)
side effects
Undesirable effects of drugs on host cells
Narrow-spectrum drugs
Attack only a few different pathogens (specific)
What is an example of something a narrrow-spectrum drug would target?
Only gram positive or only gram negative cells
Broad-spectrum drugs
Attack many different pathogens
What is the difference between cidal agents and static agents?
Cidal agents kill while static agents inhibit
What is defined as the lowest concentration of a drug that prevents growth of a particular organism?
Minimal Inhibitory Concentration (MIC)
What is defined as the lowest concentration of a drug that kills the pathogen?
Minimal Lethal concentration
What does the dilution susceptibility test observe?
If there is growth or no growth in a mueller-Hinton broth
What test used to determine the level of anti microbial activity is considered a qualitative test and involves discs?
Kirby-Bauer method
Is an E-test convenient for aerobic or anaerobic pathogens?
Anaerobic
What happens in an E-test?
Multiple E-test strips are placed to test many bacteria types at the same time. These strips contain a gradient of antibiotic, and the intersection of elliptical zone of inhibition with the strip indicates MIC
The antibiotics for each part of the cell is very _______
Specific
What is the problem with antibiotics?
Resistance
Can a species have resistance to multiple drugs?
Yes, it is a problem in hospitals
What happens when you stop taking an antibiotic too early?
You risk the bacteria becoming resistant to the drug
should you use the oldest version or newest version of an antimicrobial drug first?
You should use the oldest effective antimicrobial drug because treating a disease for the first time with the newest drug will cause it to possibly become resistant
Why should you monitor antimicrobial use?
Because unnecessary treatment enhances potential for antimicrobial resistance
Antibiotics are inhibitors of the synthesis of what?
Cell walls
What are three types of inhibitors of cell wall synthesis?
- Penicillins
- Cephalosporins
- Vanomycin
What is the name of the enzyme that can inactivate abeta-lactam ring?
beta-lactamase
Does beta-lactam bind to penicillin in a reversible or irreversible way?
Irreversible
What is an example of a beta-lactamase inhibitor?
Clavulanic Acid
Does Clavulanic acid inactivate reversibly or irreversibly?
Irreversibly
What originated from a fungus in the class Cephalosporium, contains a beta-lactam ring, and has 4 broad generations?
Cephalosporins
What are two characteristics of Vanomycin?
- Glycopeptide antibiotic
- Binds D-ala — D-ala
- is a “last resort drug”
What three antibiotics are protein synthesis inhibitors?
- Aminoglycosides
- Tetracyclines
- Macrolides
What do AL Aminoglocosides contain?
Cyclohexane ring and amino sugars
What type of antibiotics are Aminoglycosides?
Bactericidal
What are the three common resistance mechanisms of Aminoglycoside Resistance?
- Acetylation of an amino group of the 30S subunit
- ATP- dependent adenylation of a hydroxyl group
- ATP- dependent phosphorylation of a hydroxyl group
Other than Aminoglycosides, what else binds to the 30S subunit?
Tetracyclines
What type of antibiotic are Macrolides?
Bactericidal
What is an identifying characteristic of Macrolides?
12-22 Carbon lactose rings linked by one or more sugars
What are the two metabolic inhibitors that target the Folic acid bio synthetic pathway?
Sulonamides and Trimethoprim
for Sulfanilamide, what kind of mutation inhibits the binding of the enzyme dihydropteroate synthetase to the drug?
A Point Mutation
For Trimethoprim, what causes dihydrofolate reductase to not be able to bind?
Resistance
Resistance is always a ___________ mutation
Spontaneous
