Exam #2 Flashcards
Define in simple terms what is a virus.
A virus is made up of nucleic acids. They infect ALL groups of living cells. They do not exhibit the characteristics of a living organism, but they can regulate life functions of their host cells.
What are the characteristics of viruses. (6)
Viruses are filterable agents
Viruses are obligate intracellular “nucleic acid parasites”
Viruses can’t make energy or proteins without the host cell
Virus genomes can be DNA or RNA but NOT both
Viruses can have a capsid or capsid + envelope
Viral components are assembled and don’t replicate by division
How are viruses classified or named? (6)
1) Structure: size, morphology, and nucleic acid
2) Biochemical characteristics:
3) Disease
4) Means of transmission
5) Host cell (host range)
6) Tissue or organ (tropism)
Mode of transmission for virus?
Enteric
Respiratory
Zoonotic
Sexually Transmitted
Enteric mechanism & examples
Fecal-Oral Route
Wide-spectrum of activity
Enteroviruses (polio, coxsackie B); rotaviruses (diarrhea)
Respiratory mechanism & examples
Respiratory or salivary route
Influenza, measles, rhinovirus (colds)
Zoontoic mechanism & examples
vector (usually an insect); animal to human directly
rabies, cowpox, dengue
Sexually Transmitted mechanism & examples
sexual contact
herpes simplex virus-2, HIV
Structure of Naked Viruses & 2 examples
Capsid ( made up of capsomers/protein coat) + Nucleic acid
Examples = Adeno & Papilloma
Structure of Enveloped Viruses & 2 examples
Naked virus (Capsid +Nucleic Acid) + Envelope (lipid bilayer) Examples = Pox & Herpes
Naked Viruses are released by the cell via______ and are stable to….. (5)
(lysis) Temperature Acid Proteases Detergents Drying
Enveloped Viruses are released by the cell via ______ and _______and are unstable to….(4)
(lysis & budding) Acid Detergents Drying Heat
Naked Viruses Consequences (5)
Can be spread easily (on fomites, from hand to hand, by dust, by small droplets)
Can dry out and retain infectivity
Can survive the adverse conditions of the gut
Can be resistant to detergents and poor sewage treatment
Antibody may be sufficient for immunoprotection
Enveloped Viruses Consequences (6)
Must stay wet
Cannot survive the gastrointestinal tract
Spreads in large droplets, secretions, organ transplants, and blood transfusions
Does not need to kill the cell to spread
May need antibody and cell-mediated immune response for protection and control
Elicits hypersensitivity and inflammation to cause immunopathogenesis
DNA viruses & examples
Enveloped:Pox (smallpox), Herpes(HSV1), & Hepadna (Hep B)
Naked: Polyoma (JC Virus), Papilloma (HPV), Adeno (adenovirus)
RNA virus & examples (7)
Paramyxovirida (measles) Orthomyxovirida (influenza) Coronaviridae (SARS) Rhabdoviridae (Rabies) Filoviridae (Ebola) Bunyaviridae (Hantavirus) Retroviridae (HIV)
Mode of infection of Viruses? (8)
Recognition of the target cell Attachment Penetration Uncoating Macromolecular (Gene Expression) synthesis Assembly of virus Budding of enveloped viruses Release of virus
Where do RNA viruses grow in the cell ,where do DNA viruses grow?
DNA: nucleus
RNA: cytoplasm
*Where does the flu virus grow?
nucleus
*Where does the pox virus grow?
cytoplasm
Viral acute vs. Chronic vs. Persistent vs. Latent diseases. Give 2 examples for each.
- Acute: rapid onset of disease, brief period of symptoms, & resolution within days (influenza & rhinovirus)
- Chronic: a type of persistent infection that is eventually cleared, cells are not killed OR the cells are killed so slowly that there is no net cell death (Hep B & Hep C)
- Persistent: last for long periods, occurs when the primary infection is not cleared by the adaptive immune response (measles & HIV-1).
- Latent: a type of persistent infection, last through the life of the host, acute infection followed by period of no/little virus production, it is usually re-activated (Varicella-zoster & HSV-1 & 2)
Innate Immunity
Innate
§ Fast but non-specific; fast way to suppress infections & prevent disease
§ No memory
§ Resistance not improved by repeated contact
§ Phagocytes & NK cells
§ Soluble factors = lysozyme, complement, & acute phase proteins
Adaptive Immunity
Adaptive
§ Antigen-specific immune response
§ Produces recovery & a specific immunological memory
§ Specific memory
§ Resistance improved by repeated contact
§ B& T lymphocytes
§ Soluble factors = antibodies
Penetration of Viruses (Naked vs Enveloped)
o Naked
§ Endocytosis (enter by receptor-mediated endocytosis)
§ Viropexis (slip through; direct penetration; picornavirus & papovavirus). Hydrophobic structures of capsid proteins are exposed after virus binds to cells. This allows the virus and its genome to slip through the membrane.
o Enveloped
§ Fuse their membrane with cellular membrane
§ Endocytosis
Uncoating of Viruses (Naked vs. Enveloped)
§ Initiated by attachment to receptor or by acidic environment or proteases in an endosome or lysosome
§ DNA genome taken to nucleus while RNA genome stays in cytoplasm
o Naked
§ Nucleocapsid delivered to the site of replication & the capsid is removed
o Enveloped
§ Uncoating occurs during fusion.
Macromolecular Synthesis of Viruses
§ Early mRNA & nonstructural protein synthesis
§ Genome Replication
§ Late mRNA & structural protein synthesis
§ Post-translational modification of protein
Define First– line defense (3 Types)
Defense against entry into the body
Physical Barriers – skin, sweat
Antimicrobial substances – lysozymes (tears, saliva), lactoferrin (saliva), mucus (respiratory and geneital tract)
Normal Flora – normal flora crowds the intestines making it harder for pathogens to attach, if the pathogen cannot attach, it cannot infect the cell.
Humoral Adaptive Immunity
Involves B Cells
§ Antibody- Mediated Response
§ Involved B cells that recognize pathogens (antigens) in the lymph
§ Antigen binds to B cell
§ Helper T cell co stimulates B cell
§ B cells proliferate & make plasma cells. Plasma cells release antibodies specific to the antigen
§ B cells produce memory cells
Cell Mediated Adaptive Immunity
Involves T cells
§ This response occurs when cells display MHC markers
§ APC displaying foreign antigens bind to T cells
§ Interleukins costimulates T cell activation
§ If MHC-I & endogenous antigens are displayed, T cells proliferate producing cytotoxic T cells. CYT T cells destroy cells that present antigens
§ If MHC-II & exogenous antigens are displayed, T cells proliferate producing helper T cells. HTC release interleukins that stimulate B cells to make antibodies that bind to antigens & stimulate NK and macrophages to destroy the antigen.
List five mechanical and five chemical factors that are involved in preventing the attachment and invasion of microorganisms through the skin and mucous membranes
Mechanical – peeing, bowel movement, skin, removal of inhaled particles, cilia
Chemical – lysozymes, lactoferrin, lactoperoxidase, B-lysin, properdin
Which of the following is not a granulocyte?
a. eosinophil
b. macrophage
c. basophil
d. neutrophil
Macrophages
All blood cells originate from the
a. erythrocyte.
b. leukocytic stem cell.
c. eosinophilic stem cell.
d. hematopoietic stem cell.
hematopoietic stem cell
The leukocyte that contains histamine is the
a. lymphocyte.
b. monocyte.
c. macrophage.
d. basophil.
Basophils
The defense system utilizing highly specialized cells and chemicals that develop in response to specific organisms and foreign materials is the
a. generalized defense system.
b. innate immune system.
c. adaptive immune system.
d. autoimmunity.
adaptive immune system
Allergic reactions mainly involve
a. macrophages.
b. monocytes.
c. neutrophils.
d. mast cells.
Mast cells
Which of the following are referred to as mononuclear phagocytes?
a. lymphocytes and basophils
b. mast cells and eosinophils
c. basophils and eosinophils
d. monocytes and macrophages
monocytes and macrophages
Macrophages form giant cells and granulomas in response to
a. leprosy.
b. tuberculosis.
c. cholera.
d. AIDS.
Tuberculosis
Which of the following are antigen-presenting cells?
a. dendritic cells
b. T cells
c. erythrocytes
d. basophils
Dendritic cells
The leukocyte responsible for adaptive immunity is the
a. lymphocyte.
b. monocyte.
c. eosinophil.
d. neutrophil.
lymphocyte
Skin and mucous membranes
a. are the first line of innate immunity.
b. are the first line of adaptive immunity.
c. act as physical barriers to infection.
d. contain antimicrobial secretions.
e. a, c and d
act as physical barriers to infection
are the first line of innate immunity
contain antimicrobial secretions
Interferons, complement, lysozyme, and lactoferrin are all examples of
a. specific antimicrobial factors.
b. immune enzymes.
c. nonspecific antimicrobial factors.
d. cytokines.
nonspecific antimicrobial factors
A group of interacting serum proteins that provide a nonspecific defense mechanism is
a. complement.
b. interferon.
c. glycoprotein.
d. lysozyme
complement
C3a and C5a are involved in
a. inflammation.
b. interferon production.
c. properidin activation.
d. enhancement of phagocytosis.
e. a and d
inflammation & enhancement of phagocytosis
C3b is involved in
a. opsonization.
b. interferon production.
c. properidin activation.
d. endotoxin production
opsonization
The complex resulting from complement activity that leads to cell lysis is the
a. prostaglandin complex.
b. leukotriene activating complex.
c. membrane attack complex.
d. histamine complex.
membrane attack complex
Which of the following are most susceptible to complement lysis?
a. Gram-positive bacteria
b. Gram-negative bacteria
c. bacteriophages
c. prions
Gram negative bacteria
The low molecular weight glycoprotein produced by animal cells in response to viral
infections is
a. complement.
b. lysozyme.
c. histamine
d. interferon.interferon
The cytokine produced by animal cells in response to viral infections is
a. complement.
b. lysozyme.
c. histamine.
d. interferon.
interferon
Interferons function to make cells
a. resistant to viral replication.
b. lyse when exposed to virus.
c. non-motile when infected with virus.
d. resistant to phagocytosis.
resistant to viral replication
Which of the following cytokines is most antiviral in its action?
a. interleukin-1
b. interleukin-2
c. interferon
d. lysozyme
interferon
Which of the following statements about interferon is incorrect?
a. It only works on a few specific types of virus.
b. It makes cells resistant to viral infection.
c. It is a species specific molecule.
d. It does not directly inactivate viruses.
It only works on a few specific types of virus
Which activity of the virally-invaded cell triggers production of interferon?
a. activation of rRNA
b. movement of nuclear proteins to the cytoplasm
c. production of glycolipids
d. production of dsRNA
production of dsRNA
The four cardinal signs of inflammation are:
a. flare, wheals, fever, cough
b. rash, pus, heat, rubor
c. heat, pain, vesicles, fever
d. redness, heat, swelling, pain
redness, heat, swelling, pain
The first host response to a nonspecific tissue injury is described as
a. inflammation.
b. reaction.
c. antibodies.
d. trauma.
inflammation
The first kind of leukocyte lured to the site of inflammation is the
a. neutrophil.
b. monocyte.
c. macrophage.
d. basophil.
neutrophil
The attraction of leukocytes to the area on inflammation is referred to as
a. parasitism.
b. infection.
c. phototaxis.
d. chemotaxis.
chemotaxis
The cellular organelle responsible for the digestion of ingested infectious agents is the
a. endoplasmic reticulum.
b. Golgi apparatus.
c. phagolysosome.
d. lysosome.
phagolysosome
Following digestion of a microorganism by phagocytes, the debris is excreted by
a. ingestion.
b. exocytosis.
c. extrusion.
d. budding.
exocytosis
One of the strongest indications of infectious disease is
a. a rash.
b. nausea
c. headache.
d. fever
fever
Pyrogens are
a. fever-inducing substances.
b. fever-inhibiting substances.
c. phagocytosis-enhancing substances.
d. complement activators.
fever-inducing substances
Fever
a. enhances bacterial growth.
b. inhibits bacterial growth.
c. speeds up the body’s reactions.
d. triggers complement .
e. b and c
inhibits bacterial growth
speeds up the body’s reaction
Toll-like receptors
a. are cytokines.
b. each recognize a specific “danger” molecule.
c. transmit a message to the cell’s nucleus.
d. are part of adaptive immunity.
e. b and c
each recognize a specific “danger” molecule.
transmit a message to the cell’s nucleus.
Interleukins are
a. produced by leukocytes.
b. important in both innate and adaptive immunity.
c. involved in directly killing tumor cells.
d. lipid molecules.
e. a and d
produced by leukocytes.
lipid molecules.
Complement
a. may be activated through three pathways. b. disrupts the cytoplasmic membrane of invading bacteria and foreign cells. c. is part of the adaptive defense system. d. is a group of blood proteins. e. a, b and d
may be activated through 3 pathways
disrupt the cytoplasmic membrane of invading bacteria and foreign cells
a group of blood proteins
Function of:
polymorphonuclear neutrophils
carry oxygen
Function of:
eosinophils
inflammation and immunity against parasites
Function of:
basophils
mast cells
release histamine
Function of:
lymphocytes
participate in adaptive immune response
T/F White blood cells called leukocytes are important in immunity.
TRUE
T/F Mast cells are only found in the blood.
FALSE
T/F Lymphocytes are the cells primarily responsible for the specific immune responses.
TRUE
T/F Lymphocytes that mature in the bone marrow are called T cells.
FALSE
T/F Gram-negative bacteria are less susceptible to complement lysis than Gram-positive
bacteria.
FALSE
T/F Interferon directly interacts with and destroys viruses.
FALSE
T/F Neutrophils are the second phagocytic cell to respond to an infection.
FALSE
T/F Fever often enhances bacterial survival during an infection.
FALSE
T/F Defensins are short antimicrobial peptides found within mucus membranes and
phagocytes.
TRUE
List the outcomes of complement fixation (3)
Inflammation
Opsonization
Lysis of foreign cells
List the 7 steps that occur during the process of phagocytosis
- Chemoattractants, such as C5a, attract phagocyte to organisms to be ingested.
- C3b coats organisms and attaches to C3b receptors on phagocyte.
- Organism is engulfed into a phagosome.
- Phagosome fuses with lysosome to produce phagolysosome.
- Organism is killed within the phagolysosome.
- Digestion and breakdown of organism within phagolysosome.
- Contents of phagolysosome eliminated by exocytosis.
List 3 phagocytic cells
Neutrophils, Macrophages, and Monocytes
What are the signs of inflammation?
Pain (chemical release),
swelling (influx of fluid into damaged region),
redness (vasodilation),
heat (increase of blood flow),
lost of function (increased swelling and pain)
Antibody
Antibody – immunoglobulin will recognize an antigen in a specific manner and will bind + destroy it
Antigen
Antigen – foreign molecules that belongs to pathogen and is detected by immune cells
Primary Response
Primary Response – exposure produces memory cells
Memory Cells
Memory Cells – B and T cells have memory cells in case of reinfection for a faster and more efficient immune response
Cells only involved in innate immunity. (5)
Inflammation – Innate Basophils – Innate Mast cells – Innate Eosinophils – Innate Complement – Innate Interferon fever – Innate
Cells only involved in adaptive immunity. (5)
Antibodies – Adaptive Antigens – Adaptive Memory Response – Adaptive B cells – Adaptive T cells – Adaptive
Cells involved in both adaptive & innate immunity. (3)
Neutrophils – Both
Macrophages – Both
Natural killer (NK) cells – both
Write the function of the following specific regions of an antibody.
Fab region – antigen binding, variable region
Fc stem region – self molecules, constant region
Chemotaxis
Chemotaxis – phagocytes are attracted to pathogens by chemotaxis
Phagolysosome
Phagolysosome – phagosome fuses with lysosome
Opsonization
Opsonization – allows the receptor on phagocyte to bind to the c3b which facilitates phagocytosis to make pathogen more susceptible to phagocytes
Compare humoral immunity and cell-mediated immunity
Humoral
•Lead to production of antibodies (Ab) aka Ig (immunoglobulins)
•1 antibody = 1 antigen
•B lymphocytes aka B cells produce antibodies
Cell mediated Immunity
•Activate Tc Cells which destroy infected self cells
Which cells are involved in the adaptive immune response.
ADAPTIVE
• Humoral immunity – involves the production of antibody molecules in response to an antigen and is mediated by B-lymphocytes
• Cell-mediated immunity – involves the prodcution of cytotoxic T-lymphocytes, activated macrophages, activated NK cells, and cytokines in response to an antigen and is mediated by T-lymphocytes
Which cells are involved in the innate immune response
INNATE
• phagocytic cells (neutrophils, monocytes, and macrophages);
• cells that release inflammatory mediators (basophils, mast cells, and eosinophils);
• natural killer cells (NK cells); and
• molecules such as complement proteins, acute phase proteins, and cytokines.
Mucociliary Escalator
The cilia are continually beating, pushing mucus up and out into the throat. The mucociliary escalator is a major barrier against infection. Microorganisms hoping to infect the respiratory tract are caught in the sticky mucus and moved up by the mucociliary escalator; cilia release chlorine and water flows through
Role of Capsid/Envelope in Virus
Protection
Delivery Vehicle during transmission & spreading through host to target cells
Mediate interaction between virus and target cell
What happens if the outer package of a virus is inactivated or disrupted?
the virus becomes inactivated
3 Granuloytes
Basophils, Eosinophils, & Neutrophils
function of neutrophils
first to arrive from blood circulation during immune response
phagocytize cells
function of monocytes
migrate from outside of the blood to go into tissues, phagocytize and
digest, can be macrophage or dendrites
function of macrophages
first to arrive via tissue (intracellular), not in blood but in the lymph
nodes, aerobic manner of killing, travel to site of infection, send cytokines to lymphocytes,
present antigens and phagocytize
function of lymphnodes
very specific (adaptive immune response), identify and destroys pathogen
What are the functions of the following specific regions of an antibody; Fab & Fc regions
Fab region – antigen binding, variable region
Fc stem region – self molecules, constant region
Ig A
(dimer in secretions) – prevents attachment of pathogen on tissue or surface of cell, most
predominant, found in mucus and breast milk
Ig M
(pentamer) – has 10 variable regions that detects more than others and complement
activation
Ig G
(monomer) -surrounds pathogen, most numerous during infection, cross placenta and go
to the fetus (ONLY one that can do this), does opsonization, ADCC (antibody dependent cellular
cytotoxicity) and compliment activation
Ig E
(monomer) – sits on basophils and mast cells (inflammation/allergic reactions), blood
circulation
Ig D
(monomer) – occurs on B cells, involved with development and maturation of antibody
response
Glycoproteins that react specifically with the chemical structures in the antigen that induced them are called
a. determinants.
b. antibodies.
c. proteases.
d. macroproteins.
antibodies
Antibodies are made by
a. red blood cells.
b. macrophages.
c. B cells/plasma cells.
d. T cells.
B cells/plasma cells
T cells primarily are responsible for
a. humoral immunity.
b. cell-mediated immunity.
c. anamnestic immunity.
d. producing haptens
cell mediated immunity
Macrophages and dendritic cells are
a. T cells.
b. B cells.
c. antigen-presenting cells.
d. antibody-producing cells.
antigen presenting cells
Epitopes or antigenic determinants
a. are parts of the antibody molecule.
b. are T cell receptors.
c. are a portion of antigen recognized by antibody.
d. may be approximately 10-25 amino acids in length.
e. c and d
area a portion of antigen recognized by antibody
may be approximately 10-25 aa in length
The humoral immune response involves the manufacture and use of
a. antibodies.
b. T cells.
c. lymphokines.
d. antigens.
antibodies
Specific chemical groups on an antigen molecule to which the immune response is directed
are
a. antigenic determinants.
b. an autoimmune response.
c. monomers.
d. allergens.antigenic detereminants
A term synonymous with antibody is
a. antigen.
b. epitope.
c. determinant.
d. immunoglobulin.
immunoglobulin
Secondary lymphoid organs
a. are strategically located in the body.
b. facilitate interactions between cells.
c. are hematopoietic.
d. are the site of T cell maturation.
e. a, b
are strategically located in the body
facilitate interactions between cells
Which of the following do not induce a strong immune response?
a. lipids
b. proteins
c. polysaccharides
d. nucleic acids
e. a and d
lipids and nucleic acids
The chains of an antibody molecule are bonded to one another by
a. disulfide bonds.
b. hydrogen bonds.
c. ionic bonds.
d. oxygen bonds.
disulfide bonds
Which of the following antibodies is a pentamer?
a. IgA
b. IgD
c. IgM
d. IgE
IgM
Which of the following antibodies is a dimer?
a. IgA
b. IgD
c. IgM
d. Ig
IgA
The immunoglobulin monomer consists of
a. 4 large chains.
b. 2 heavy and 2 light chains.
c. 5 light chains.
d. 3 heavy and 3 light chains
2 heavy and 2 light chains
Which class of antibody accounts for the bulk of the circulating antibody?
a. IgA
b. IgD
c. IgG
d. IgE
IgG
An IgG molecule has two
a. heavy chains.
b. light chains.
c. antibody binding sites.
d. antigen binding sites.
e. a, b and d
heavy chains
light chains
antigen binding sites
Antigens interact with antibodies at
a. the outer end of each arm of the Y.
b. the junction of heavy and light chains.
c. different regions depending on the class of antibody.
d. the bottom stem of the heavy chain of the Y.
the outer end of each arm of the Y
The only class of antibody that can cross the placenta is
a. IgA.
b. IgD.
c. IgG.
d. IgE.
IgG
Which is the first antibody class made during the primary response to an antigen?
a. IgA
b. IgM
c. IgG
d. IgE
IgM
Which of the following is the most abundant immunological class produced?
a. IgA
b. IgD
c. IgG
d. IgE
IgA
Which of the following class of antibody is primarily found in external secretions?
a. IgA
b. IgD
c. IgG
d. IgE
IgA
The immunoglobulin that is important in hypersensitivity reactions is
a. IgA.
b. IgD.
c. IgG.
d. IgE.
IgE
The cells that actually secrete antibodies are
a. plasma cells.
b. natural killer cells.
c. phagocytes.
d. T cells.
plasma cells
CD4 cells are often
a. T helper cells.
b. T suppresser cells.
c. T cytotoxic cells.
d. T hypersensitivity cells.
T helper cells
CD8 cells are often
a. T helper cells.
b. T suppresser cells.
c. T cytotoxic cells.
d. T hypersensitivity cells.
T cytotoxic cells
Antigens may be processed for presentation by
a. macrophages.
b. dendritic cells.
c. erythrocytes.
d. T cytotoxic cells.
e. a and b
macrophages
dendritic cells
Class II MHC molecules are found primarily on
a. macrophages.
b. dendritic cells.
c. erythrocytes.
d. T cytotoxic cells.
e. a and b
macrophages
dendritic cells
The stimulation of B cells to divide and mature is provided by
a. T helper cells.
b. macrophages.
c. T cytotoxic cells.
d. plasma cells.
T helper cells
Which is involved in reacting to virus- infected cells?
a. cell-mediated immunity
b. T cytotoxic cells
c. B cells
d. MHC I
e. a, b and d
cell mediated immunity
T-cytotoxic cells
MHC Class I
CD4 bind
MHC II
CD8 bind
MHC I
Perforin is produced by
a. B cells.
b. macrophages.
c. NK cells.
d. T helper cells.
e. b and c
NK cells
Apoptosis
a. is a form of cell suicide.
b. is induced in target cells by effector T cytotoxic cells.
c. results in T cell death.
d. refers to the transformation of B cells into plasma cells.
e. a and b
a form of cell suicide
is induced in target cells by effector T cytotoxic cells
agglutinates antigens
IgM or IgG
found on surface of B cells
IgD
first antibody produced during primary response
IgM
protects mucous membranes
IgA
involved in hypersensitivity
IgE
T/F T cells are responsible for directly manufacturing antibodies.
FALSE
T/F T cell receptors are identical to antibodies.
FALSE
T/F Antibody and antigen are held to one another by covalent bonds.
FALSE
T/F Gene rearrangement is responsible for the generation of the various antibody molecules.
TRUE
