69 terms

Microbiology Exam 5 (Rosing MTSU)

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nonspecific defenses of host
Function:
To protect the body from all foreign substances
Reacts the same way to any/all foreign substances
-pollen, chemicals, splinter, microbes
metabolism / physiology
TYPE OF NONSPECIFIC DEFENSE due to _______

i. Bacillus Anthracis
1. Causes anthrax [disease of warm-blooded animals like cattle and humans]
2.*BUT* Amphibians body temp are too low and birds are too high

ii. Rabies
1. Raccoons, skunks (Body temp 100-103*F)
2. Opossums almost never get rabies (Body temp 90-99*F)
external defense barriers
TYPE OF NONSPECIFIC DEFENSE due to __________
*i. Intact skin/ physical barrier*

1. (has acid mantle) pH 3-5
2. microbial antagonism
a. when a bacteria that is supposed to be there is takena way, so other bacteria make way to take over.
external defense barriers
TYPE OF NONSPECIFIC DEFENSE due to __________

ii. Mucus Membranes
1. Lysozyme is an antibacterial
a. Found in tears/salinva
b. IgA antibodies
i. Most bacterial infections begin on mucus membranes somewhere

1. The choice seldomly made:
a. Whooping Cough is a bacteria will attach to a mucous membrane [Bordetella Pertussis]
b. Corynebacterium diptheriae :upper mouth infection.
c. Vibrio cholera: CHOLERA! Grows on villi in the intestine.
i. All three of these cause their disease symptoms by staying at the point of first attachment, grow, and liberate toxins.

2. The choice most often made: enzymatic digestion to submucosa [dissolve their way through mucous membranes]. They spread through the circulatory system/lymphatic system
intact skin & mucous membranes
types of external defense barriers
lysozyme
an enzyme found in saliva and sweat and tears that destroys the cell walls of certain bacteria
IgA
main antibody type in secretions such as saliva and milk; prevents pathogens from attaching to epithelial cells in digestive and respiratory tracts
mucous membrane
This membrane contains lysozyme, and IgA antibodies
IgA
Secretory antibody.
Located on mucosal surfaces, in secretions.
Whooping cough
Bordetella pertussis - bacteria will attach to a mucous membrane
diptheria
Corynebacterium diptheriae - upper mouth infection.
Cholera
Vibrio cholerae - Grows on villi in the intestine.
Mucous membrane
These Bacterial infections start on a _______________

Bordetella pertussis
Corynebacterium diptheriae
Vibrio cholerae

i. All three of these cause their disease symptoms by staying at the point of first attachment, grow, and liberate toxins.
Internal Defense Mechanisms
general mechanisms that deal with invading pathogens once they have crossed epithelial barriers or have release chemicals which enter blood or lymph
phagocytes
white blood cells that digest & destroy microorgasims and other unwanted substances - part of immunity system

(encompasses both neutrophils and monocytes)
neutrophil
a. Humans make 10^11 of thse every day from the bone marrow.
b. They are short lived. Live 2-3 days.
i. circulate within the blood stream for 2-3 hours.
ii. Escape circulations and move into body tissues [last for a couple of days].


The most abundant type of white blood cell. Neutrophils are phagocytic and tend to self-destruct as they destroy foreign invaders, limiting their life span to a few days.

SHORT-LIVED
monocytes
a. Circulate when produced by the bone marrow
i. Escape through capillary walls into tissues
ii. Survive in tissues from several days to several months.

white cells with a single nucleus; the largest normal blood cells. During inflammation, monocytes mature and grow to several times their original size, becoming macrophages.
chemotaxis
inflammatory chemicals attract neutrophils to the injury site
Principal events of phagocytosis
A.) Chemotaxis - [HOW?] [attraction from the host to the phagocyte?]

B.) Attachment- [of the offending bacterium to the plasma membrane of the engulfing cell]
- i. ENCAPSULATED BACTERIA WILL NOT BIND TO THE PHAGOCYTE MEMBRANE!
- ii. Smear antibodies onto the capsule of the bacteria

C.) Extension and fusion of Pseudopodia
- i. Extended the membrane to make "arms" to grab it [pseudopodia].
- ii. Traps it against a rough surface of some sort [A CLOT!!!]
- iii. Extend pseudopodia around the bacteria and between the clot and bacteria [pinned the bacteria up against a surface].
- iv. FORMS A FOOD VACUOLE= PHAGOSOME!
- v. Dump lysosomal digestive enzymes into the phagosome forming a phagolysosome. / Lysosome fused with phagosome to make phagolysosome

D. Bacteria will be dead in 10-30 minutes. And digested in a couple of hours.
phagocytosis
process by which a cell engulfs foreign substances or other cells; "cell eating"; white-blood cells, called phagocytes, engulf pathogens
inflammation
1. Animal tissues react to disease-causing antigens or allergy-causes antigens or mechanical injury by secreting histamine.
a. We are pulling the CO2 out of histidine to make histamine. [histadine carboxylase is the enzyme]
b. Histamine is GOOD and inflammation is GOOD
c. Histamine causes a dilation of capillaries [redness and warmth]
i. Increased permeability of capillaries
1. Makes it easier for amoeboid WBC to escape the tissue and into infected tissue.
ii. Histamine induces smooth muscle contractions. [that throbbing and pain sensation]
Interferon - LMW proteins
[low molecular weight//SMALL proteins that are soluble]

1. When an animal cell is challenged with a virus [introduced to a virus] it will begin to produce interferons.
a. Interferons say "The virus is coming, the virus is coming!"
i. Intercellular message molecules
ii. Lets cells in the distance know that viruses are coming
iii. The cells in the distance produce a variety of antiviral compounds that interfere with the viruses ability to replicate.
iv. Interferons are indirectly antiviral because they don't do anything to the virus, but they are messages that let the cells in the distance know about the virus that is coming for them.
v. Interferons are host specific.
1. Chicken cells will produce Chicken interferons that will alert chicken cells, not human cells.
vi. NOT VIRUS SPECIFIC.
1. They don't say "pneumonia is coming!" they say "A virus of some sort is coming!"
interferon
- an antiviral protein produced by cells that have been invaded by a virus
- intercellular MESSAGE MOLECULES
- THE VIRUSES ARE COMING!!!
Specific Defenses of the Host
Host [immune responses] [LOOK AT PPT SLIDE ON THIS]
INVOLVE PRODUCTION OF SPECIALIZED CELLS AND CHEMICAL ANTIBODIES

a. IMMUNE RESPONSE=
b. Vaccines and toxoids
c. HUMORAL IMMUNE RESPONSE
IMMUNE RESPONSE
Involve the production of Specialized Cells and Specialized Chemicals (***antibodies***)

To destroy/inactivate a foreign (non-self) macromolecule (***antigen***)

Perhaps a protein, polysaccharide, etc. which might be a ***component part of a pathogen*** (capsule, cell wall, flagellum, toxin)

Or ***part of something nonmicrobial*** (pollen, egg whites, transfused blood, transplanted organs, peanuts, strawberries, etc.)
immunoglobulin
- a class of proteins produced in lymph tissue in vertebrates and that function as antibodies in the immune response

- Protein (globulin) with antibody activity; examples are IgG, IgM, IgA, IgE, IgD.
phagosome
- Intracellular vacuole containing ingested particulate materials; formed by the fusion of pseudopodia around a particle undergoing phagocytosis

-
vaccines and toxoids
Artificially induced immunity to a specific disease or toxin; oral or parenteral;

Toxoids - Tetanus, Diphtheria

Vaccines - Hepatitis A, Influenza
toxoids
Toxins that have been deliberately inactivated by heat or chemical treatment so that they are no longer toxic but can still provoke a protective immune response on vaccination.
vaccines
dose of a disabled or destroyed pathogen used to stimulate a long-term immune defense against the pathogen. A weakened form of the virus is given to the person so their immune system can build up immunity to the virus.
live vaccine
ATTENUATED

produced by taking a virus or bacteria and modifying it; altered virus/bacteria can still replicate, but it is much weaker and usually does not cause the disease
-still alive but much much weaker
-careful in immunocompromised > can contract disease
-More like a natural response so quicker and more efficient immunity
dead vaccine
A vaccine made from a weakened or dead pathogen that provides immunity against that pathogen
virulent vaccine
a. Not weakened, not killed, fully deadly.
b. Small pox vaccine was the first vaccine
i. Cow pox virus taken from cows and put on scratches/cuts on little kids so they wouldn't get small pox
ii. This virus was very similar to small pox, and the antibodies would protect against the small pox virus, as well.
Humoral Immune Response
Involve the production of antibodies found primarily in blood serum (but also in other extra-cellular fluids, once known as "humors." i.e. mucus, saliva, tears.)

- saliva, tears, etc.
- Vitreous humor (EYE JOKES)
IgG
a. immunoglobulin G class antibodies
b. 2 antigen binding sites per IgG antibodies.
c. Monomer structure
d. 80-85%
e. major circulating antibody in plasma.

Distribution: intra- and extravascular
Function: secondary response
IgM
a. Immunoglobulin macroglobulin molecules.
b. Is 5x bigger than IgG
c. Pentamer structure.
d. 5 y's from IgG that are stuck together by more s-s bonds.
e. 10 total binding sites

Distribution: mostly intravascular
Function: primary response
IgA
a. Major group in fluids bathing organ systems in contact with the external environment
b. AKA tears, saliva, mucous, breast milk.
c. IgA is a dimer!
d. Two monomers that are stuck together by a pritein sugar/polysaccharide.

Distribution: intravascular and secretions
Function: protect mucus membranes
IgD
a. O.2% of antibodies
b. Monomer structure?

Distribution: lymphocyte surface
Function: unknown
IgE
a. 0.002% of antibodies
b. monomer structure?
c. 1 in 50,000 antibodies in IgE
d. bound to plasma membrane of granulocytes

Distribution: basophils and mast cells in salive and nasal secretions
Function: protect against parasites
types of immunoglobulins
IgG - most abundant, neutralizes bacterial toxins, source of maternal antibodies
IgA - protects mucus membranes
IgM - neutralizes organisms in the blood
IgE - allergic response, parasitic infection
IgD - recognition of 'self' and 'foreign'
lysins
an antibody that induces lysis
antitoxins
produced by the host body and neutralize toxins
antigens
foreign substances that trigger the attack of antibodies in the immune response.
agglutinins
A. Causes Clumping of cellular antigens (aggutinations)
B. Makes phagocytosis from white blood cells of antigens more productive. They can eat the entire clump instead of chasing them down individually.
precipitins
-cause SOLUBLE Antigens to precipitate
-Antigen = protein, not a cell
=soluble and floating around
-generate fragments, chemicals that can lead to agglutination, eomplementing, etc.
opsonins
A. Render an encapsulated bacterium (susceptible to phagocytosis) engulfable.
B. If a bacteria refueses to attach to a bacterial cell because it has a capsule, the cell can smear it with antibodies [an opsonin] and can stick to the PM. ORRR trap against a blood clot or rough surface to pin it so it can extend pseudopodia around it.
Immobilizing antibodies
a. Antibodies that attach to the flagella on mobile antigens so they cannot rotate.

THIS MAKES THEM IMMOBILE.
complement and complement-fixing antibodies
1. Third component so antigen and antibody can interact with each other.
2. Series of II normally occurring plasma proteins.
3. C1-c9
a. C1 has subclasses c1q, c1r, c1s
b. Once the complement is fixed, it cannot be used again ever ever ever because of the antigen/antibody interactions.
c. The proteins are changed by the association.
d. AKA ACTIVATED COMPLEMENT,
i. Causes certain things to happen
ii. All the proteins that are attached [c3, c5, etc] are now changed and do certain things!
1. Etc, in the powerpoint, c3 now has opsonization effects IN CONJUNCTION WITH AN ANTIBODY. CHANGED C3.
salk vs sabin
salk- killed
sabin - not killed
Jonas Salk
Developed Polio vaccine
- This is also called IPV it is a KILLED virus that invokes and IgG response.
- Prevents disease but not infection
Albert Sabin's Vaccine
1961
- LIVE attenuated vaccine, replicates in intestines.
- Advantages: 3 oral doses, increases mucosal immunity that can create herd immunity
ELISA
- Enzyme Linked Immunosorbent Assay. This is a Basic Screening to detect HIV antibodies,

- IF POSITIVE, RETEST. This is NOT the diagnostic test. Western Blot confirms HIV.
Western Blot
-a variation on protein electrophoresis, where proteins are separated by an electrical charge
-a combination of electrophoresis and ELISA
-rxns are carried out in agar gel, then proteins are transferred to nitrocellulose paper and identified by enzyme linked antibodies (FA)
- common example is the confirmation of a positive HIV test
natural killer cell
lymphocyte which recognizes and destroys foreign cells or infected host cells in a nonspecific manner
histamine
chemical released by activated mast cells that increases the flow of blood and fluids to the surrounding area
ELISA
Tests for HIV, Parvo, etc.
Problems with ELISA
1. Can have false negative. Prime time to test for HIV in ELISA in 4 months within infection time.
2. Antibodies used that are directed against the flu will also react with GP120 to give a false positive. [GP 120 is very similar to surface envelope proteins like in the flu]
Home HIV test
A.) Have a detecting antibody on the test strip. [at the c]
i. There should ALWAYS be a reaction there.
ii. This is called the control line

B.) T site that represents HIV envelope proteins [probably GP120]
i. Will have a band there, as well, if it is positive.
ii. If positive, would follow up with the western blot test.
iii. Prone to false positives and false-negatives just like the ELISA, but the ELISA is more sensitive.
antigen presenting cell
A cell that upon ingesting pathogens or internalizing pathogen proteins generates peptide fragments that are bound by class II MHC molecules and subsequently displayed on the cell surface to T cells.

*Macrophages**, dendritic cells, and B cells are the primary antigen-presenting cells.
th2
CD4 T Cell that promotes humoral immune response by activating B cells to make antibodies
gp120
Protein of HIV envelope. Binds CD4 and CCR5 chemokine receptor of T cell. Binding of CD4 on T cell causes conformational change and uncovering of gp120 parts that bind CCR5.

Hidden gp41 part allows HIV to evade the immune system because there is no antibody response to hidden part. Diagnosis of HIV includes Western blot test for the antibody to gp120.
Sites of antibody formation
- lymph nodes
- spleen
- MALT (MUCOSAL-ASSOCIATED LYMPHOID TISSUE)
MALT
Mucosal-Associated Lymphoid Tissue;
-composted of Peyer's patches, tonsils, appendix and lymphoid nodules in the bronchii; protects passages that open to exterior from the nerver-ending onslaughts of foreing matter entering them
macrophage
A phagocytic cell present in many tissues that functions in innate immunity by destroying microbes and in acquired immunity as an antigen-presenting cell.
th1
- CELL
- Inflammatory
- Activated in MICROBIAL INFECTIONS;
- Activates macrophages and PGs (prostaglandins) -> Increase in blood flow, edema and fever
cell mediated immunity
when immunity relies on lymphoctyes, like helper and killer t cells, the first type of t cells activating the latter, which ruptures macrophage and kills the infected cell
tc cell
lymphocyte - Cytotoxic T cell Tc. Lysis of plasma membranes containing antigens bound to Class 1 MHC proteins, secretion of perforins, defensins, lymphotoxins and more
perforin
A protein secreted by a cytotoxic T-cell that lyse (ruptures) an infected cell by perforting its membrane.
gm-csf
granulocyte-macrophage colony-stimulating factor

*cytokine secreted by macrophages to promote growth of myeloid progenitor cells and their differentiation to granulocytes