Final Exam Flashcards
What are the main antigen categories?
proteins and polypeptides: enzymes, cell surface structures, and exotoxins
lipoproteins: cell membranes
glycoproteins: blood cell markers
nucleoproteins: DNA complexed into proteins, but not pure DNA
polysaccharides: (certain bacterial capsules) and lipopolysaccharides
alloantigens
cell surface markers and molecules that occur in some members of the same species, but not others
what are alloantigens the basis of
basis for an individual’s blood group and MHS profile
responsible for incompatibilities that can occur in blood transfusion or organ grafting
superantigens
bacterial toxins that are potent stimuli for T cells
activate T cells at a rate of 100 times greater than ordinary antigens
result can be overwhelming release of cytokines and cell death
allergens
antigens that evoke allergic reactions
antigen-presenting cells
dendritic cells, macrophages, B cells
T-cell-indepedent antigens
antigens that can trigger B cells directly without APCS, or T helper cells
virally infected cells
recognize virus peptides displayed on the cell surface
intracellular bacterial infections
Tc cells can destroy
cancer cells
Tc constantly survey the tissues and immediately attack any abnormal cells they encounter
gamma-delta T cells
have T-cell receptors rearranged to recognize a wide range of antigens
frequently respond to certain kinds of PAMPs in the same way as nonspecific WBCs
respond more quickly and produce memory cells
natural killer (Nk) cells
lack specificity for antigens
circulate through the spleen, blood, and lungs
probably first killer cells to attack cancer cells and virus-infected cells
destroy these cells in a similar fashion as T cells
not part of specific immunity, but sensitive to interferon
natural killer T (nkt) cells
hybrid cells that are part killer cell and part T cell
have T-cell receptors for antigen and ability to release large amounts of cytokines very quickly, leading to cell death
another bridge between nonspecific and specific immunity
hypervariable region
the site of the antibody where the epitope begins
amino acid content is extremely varied
opionization
attachment of antibody to foreign cells and viruses is followed by binding of the Fc end to phagocytes
isotopes
structural and functional classes of immunoglobins
what are the two forms of IgA
dimer and monomer
monomer that circulates in small amounts in the blood
dimer that is a significant component of mucous and secrous secretions of the salivary glands, intestine, nasal membranes, breast, lung, and genitourinary
colostrum
earliest secretion of breast milk; high in IgA that coats the gastrointestinal tract of a nursing infant
natural immunity
any immunity that is acquired through the normal biological experiences of an individual
artificial immunity
protection from infection obtained through medical procedures such as vaccines and immune serum
how does active immunity occur
occurs when an individual receives immune stimulus that activates B and T cells to produce immune substances such as antibodies
what are the three characteristics of active immunity
creater memory that renders the person ready for quick action upon re-exposure to the same antigen
requires several days to develop
lasts for a relatively long time
how does passive immunity occur
occurs when an individual receives antibodies from another human or animal
recipient is protected for a short period fo time even though they have not had prior exposure
what is passive immunity characterized by
lack of memory for the original antigen
lack of production of new antibodies against the disease
immediate onset of production
short-term effectiveness as antibodies have a time limit
what was the first immunization attempt like?
consisted of drying and grinding up smallpox scabs & blowing them with a straw into the nostrils of vulnerable family members
variolation in the 10th century
deliberate innoculation of dried pus from smallpox pustules of one patient into the arm of a healthy person
used in parts of the Far East until it was brought to England
Edward Jenner
inspired by dairymaid who had been injected by cowbox and who was immune to smallpox
tested theory by injecting a young boy with material from human cow pox lesions, exposed him to small pox two months later, and the boy proved immune to the disease
what was Jenner’s discovery
a less pathogenic agent could confer protection against a more pathogenic one
vaccination
any immunity obtained by inoculation with selected antigens
natural passive immunization
a developing fetus encounters selected antibodies that cross the placental barrier (IgA)
nursing newborn baby receives IgA antibodies from mother’s breast milk
artificial passive immunization
involved the transfusion of horse serum containing antitoxins to prevent tetanus and treat diphtheria
gamma globulin
immunoglobin extracted from the pooled blood of many human donors
processing concentrates antibodies to increase potency and eliminate potential pathogens
artificial active immunity vaccinations
stimulate a primary response and memory response
prime the immune system for future exposure to a virulent pathogen\
if pathogen enters body, response will be immediate, powerful, and sustained
principles of vaccine preparation
protects against exposure to natural, wild forms of pathogen
have a low level of adverse side effects or toxicity; not cause harm
stimulate both antibody(B-cell) and cell-mediated(T-cell) response
long-term lasting effects
does not require numerous doses or boosters
whole cell or virus vaccines
live, attenuated cells or viruses
killed cells or inactivated viruses
conjugated vaccines
subunits conjugated with proteins to make them more immunogenic
dna vaccines
microbial DNA is inserted into a plasmid vector and inoculated into a recipient
human cells will take up some of the plasmids and expell the microbial DNA in forms of proteins
these foreign proteins will be recognized during immune surveillance and cause B and T cells to be sensitized
mRNA viruses
new with covid-19 Pfizer and Moderna vaccines
MRNA covid vaccines
MRNA translated to form proteins
MRNA is fragile would be destroyed(chopped up) by our natural enzymes if it were injected directly into the body
entering cells
adenovirus binds to receptors on cell surface and enter the cell
DNA for the gene that codes for the spike protein is injected into the cell nucleus
route of administration of vaccines
most vaccines: subcutaenous, intramuscular, intradermal
nasal and oral vaccines: available for only a few diseases, stimulates IgA production on mucuous membrane, easier to give than injections
adjurants
special binding substance required by some vaccines which enhances immunogenicity, prolongs antigen retention at injection site, etc
vaccine complications
vaccines must go through experimental tests but some complications occur:
local reactions at infection site
fever
allergies
other adverse outcomes
more serious reactions are extremely rare
acquired immunodeficiency syndrome
viral disease that attacks the immune system(lymphatic system disease)
first reported cases were in U.S. in 1981
what is the causative agent of AIDS
human immunodeficiency virus(HIV)
how many people have been infected with AIDS
at least 80 million people have been infected since early 1980s worldwide with HIV
what is the mode of transmission for HIV infection and AIDS transmission
direct contact
sexual contact(semen, vaginal fluids) with infected individuals
exposure to blood infected with HIV(needle sharing, blood transfusion, mother to infant in utero, open wounds)
what is HIV susceptible to?
does not survive outside host for long
susceptible to heat and disinfectants
what race is more likely to get HIV
African American men 7x more likely
human immunodeficiency virus overview
retrovirus in the genus Lentivirus
many retroviruses have the potential to cause cancer
produce dire, often fatal, diseases and are capable of altering the host’s DNA
what two types are HIV divided into
HIV-1 is the more virulent type(99% of AIDS worldwide)
HIV-2 is less virulent and causes milder, AIDS-like disease and replicates predominately in macrophages, dendritic cells, and T cells
HIV infection and Aids causative agent
contain reverse transcriptase (RT), a “retrovirus”
catalyzes the replication of double-stranded DNA from a single-stranded RNA
can permanently integrate viral genes into the host genome that is then passed on to progeny cells
enveloped RNA virus
outermost layer is a lipid envelope
membrane glycoprotein spikes mediate viral adsorption to the host cell
can only infect host cells that display a combination receptor consisting of the CD4 marker plus the coreceptor CXCR-4
HIV pathogenesis
infects Th cells(CD4 or T4), macrophages, dendritic cells, monocytes, and B lymphocytes
HIV also interacts with coreceptors CCR-5 on target cells
enters a mucuous membrane or the skin and travels t dendritic cells that reside beneath the epithelium
where does HIV virus mainly reside?
96% of HIV virus in lymph nodes, 4% in the blood
how does the host lose the battle?
HIV infection does not always immediately kill the host cell
results in symptoms in host: fever, fatigue, weight loss, diarrhea, body aches
2 billion immune cells destroyed daily by HIV
over time, years, immune system cannot keep up
what are symptoms of HIV directly tied to
level of virus in the blood
level of T cells in the blood
what does diagnosis with AIDS require
(1) testing positive for the virus and
(2) meeting one of the following criteria:
CD4 cells below zoocells/microliter of blood
CD4 cells account for fewer than 14% of lymphocytes
experience one or more AIDS-defining illnesses
what are the initial symptoms of HIV and AIDS
fatigue, diarrhea, weight loss, and neurological changes
opportunistic infections or neoplasms(cancer)
what are some of the most virulent complications of HIV/AIDS
lesions occur in the brain, meninges, spinal column, and peripheral nerves
patients with nervous system involvement show some degree of withdrawal, persistent memory loss, spasticity, sensory loss and progressive AIDS dementia
how to prevent aids
avoid sexual contact with someone with AIds
avoid contaminated blood and breastmilk from infected people
barrier protection (e.g condoms) if HIV status unknown
preexposure prophylaxis
HIV treatment
no cure for AIDS
treatment directed at reducing viral load and disease symptoms
what are the four classes of drugs that delay the symptoms of AIDS
fusion inhibitors(FIs) prevent entry of HIV into cells by binding to gp41 protein
types of reverse transcriptase inhibitors
protease inhibitors inhibits viral maturation
integrate inhibitors
lymphatic system disease
can be caused by a number of bacteria or viruses
vast majority are caused by Epstein-Bcarr virus(EBV), a member of the human herpesvirus
initially infects B cells, later T cells
infectious mononucleosis transmission
direct oral contact and contamination with saliva are the principle modes of transmission
infected individuals will shed virus for up to 6 weeks until infection becomes latent
how does the latent infection of mononucleosis work?
latent infection will last rest of individuals life, making them a reservoir for the virus
infectious mononucleosis signs and symptoms
sore throat, high fever, swollen cervical lymphnodes, gray-white exudate in the throat, skin rash, enlarged spleen and liver
sudden leukocytosis
how long is the incubation period for mononucleosis
30 to 50 day incubation period
what is a strong hallmark of mononucleosis
fatigue
prevention and treatment of mononucleosis
rapid diagnostic tests
usual treatments are directed at symptomatic relief of fever and sore throat
antibiotics for secondary infections
no vaccines, no antivirals
hospitalization is rarely needed
what are some cancers typically associated with epstein barr virus
burkitt’s lymphoma
lymphoma
cancer of B lymphocytes
nasopharyngeal carcinoma
influenza basics
respiratory system disease caused by influenza virus
influenza A, B, C viruses in the family Orthomyxoviridae
Subtype A influenza
most common, pandemics
most important human pathogen
Subtype B influenza
“flu” symptoms
usually found primarily in humans
milder form of the illness; no epidemics/pandemics
Subtype C influenza
just a mild respiratory disease
no epidemics/pandemics
what are the most common types of invasive disease caused by Haemophilus influenzae
pneumonia(lung infection)
bloodstream infection
meningitis
epiglottitis(swelling in throat)
cellulitis(skin infection)
infectious arthritis(inflammation of the joint)
negative-sense, ssRNA virus
known for extreme variability
undergoes constant genetic changes that alter the structure of its envelope glycoproteins
envelope
matrix protein
lipid bilayer
external glycoproteins
ion channels
hemagglutinin
any of a group of naturally occuring glycoproteins that cause red blood cells(erythrocytes) to agglutinate, or clump together(used in assays to identify viruses)
neuraminidase
breaks down protective mucosa coating of respiratory tracts
assists with viral budding and release
keeps viruses from sticking together
antigenic drift
minor change in influenza virus antigens due to gene mutation(point mutations) in a strain within a geographic area
antigenic shift
major change in influenza virus antigen due to gene reassortment
2 different strains of flu viruses(from human to animals) infect the same cell
pandemic (H1N1) 2009 Influenza
6 months pandemic
started in Mexico
caused by major change in the influenza genome