Final Exam Flashcards
subversion of innate immune response (bacteria)
- evasion of antimicrobial peptides
- impairment of tracheal clearance
- adhesion and penetration of epithelial barriers
- evasion of phagocytosis
- evasion of complement killing
Different ways for bacteria to evade complement killing in innate immune response
- activate masking substance
- apply appropriate inhibitors of activation
- cover up target membrane attack complex
- inactivate complement chemotaxin c5a
- activate surface of plasminogen to plasmin and cleave c3b
subversion of adaptive immunity (bacteria)
- antigenic variation
- apoptosis or lysis of lymphocytes
- inhibition of lymphocyte proliferation
- super antigens
- effects of cytokine expression
- subversion of T regulatory cells
- degradation of immunoglobulins
immune evasion strategy by viruses
immune avoidance: -avoid exposure -location--intracellular; cell-cell spreading -immunosuppressive viral proteins immune escape: -point mutation -reassortment -recombination
immune evasion by parasites
antigenic variation molecular mimicry conceal antigen site intracellular location immunosuppression
Innate response
functions in normal host without prior exposure to invading microbes
adaptive response
consists of antibody response (humoral) and lymphocyte (cell-mediated) response
-tailored to particular microbial infection and characterized by memory
adaptive immunity
induced by exposure to an antigen, the response is specific for inducing antigens and immunologic memory is generated
innate immunity
constitutional factors: genetics, age, metabolic factors, neuroendocrine, environment
natural barriers and normal flora: mechanical (flow of fluid), chemical (sebum, enzymes, lysosome), microbiological (normal flora)
IFN (interferon) system - Antiviral defense
animal models
treatment with anti-IFN Ab
defective IFN response
abrogation of IFN-alpha/beta
Cell type involved in defense against microbes
phagocytic cells
lymphocytes
Natural Killer cells
phagocytic cells
polymorphonuclear neutrophils
mononuclear phagocytes
eosinophils
macrophages
Lymphocytes
- B cells
- T cells
Antibody producing plasma cells
cell-mediated immune response
help B cells in antibody production
Natural Killer cells (NK)
kill other rogue cells in non-specific manner
Distinguishing infected self from uninfected self: innate immune system
pattern recognition receptors -TLRs -RLRs -Complement missing/altered self receptors (NK cells)
distinguishing infected self from uninfected self: adaptive immune system
antigen presentation (MHC)
antibodies
T cell receptors
Adaptive immunity
-Humoral
mediated by antibodies secreted by B cells and plasma cells
- Primary
- first time seeing pathogen
- utilize IgM
- weaker response
- takes time to build - Secondary
- shorter lag phase
- greater magnitiude
- class-switched IgG
Adaptive immunity
-Cell-mediated
inside of the cell, memory specific
-mediated by T-cells and cytokines
~CD8+ T cell function as cytotoxic T lymphocyte (MHC I restricted)
~CD4+ TH1 cells and activated macrophages function DTH (macrophages, NK, neutrophil, eosinophils) (MHC II restricted)
Major Histocompatibility complex (MHC)
MHC I : on all nucleated cells, +APCs T cell-mediated toxicity
MHC II : only B cells, macrophages, and dendritic cells; T cell-mediated helper
Epitopes
Antigen determinants
Paratopes
antibodys
BCRs
TCRs
Endogenous Ag
intracellular pathogen
synthesized in cytosol and degraded by proteasomes in cytosolic pathway
MHC I
Exogenous Ag
processed in endosomes
macrophages engulfs and degrades bacterium, producing peptide
-peptides bound by MHC II then peptides transported by MHC II to surface
–TH1 cell recognizes complex of peptide antigen with MHC II and activate macrophages
Steps of infection
- pathogen adhere to epithelium
- skin wound lets pathogen penetrate
- local infection, innate immunity
- dendritic cells take infection to lymph node and stimulate adaptive immunity
- effector cells and molecules of adaptive immunity travel to infected tissue
Dendritic cells
- best APC to activate T cells
- critical bridge between innate and adaptive immune responses
TH1 cells
Helpers for CM1
-activate cell-mediated immunity by producing cytokines
TH2 cells
produce cytokines that promote antibody production
-helpers for B cells
Macrophages
- activate via PRRs binding PAMPs
- activateL IFN gamma from TH1 T cells in DTH reaction
- -critical for control of intra vesicular bacteria
Prevention of infectious disease: primary
avoid occurrence of infectious disease
-health promotion and specific protection
prevention of infectious disease: secondary
primary failed and you want to minimize damage after disease has occurred
prevention of infectious disease: teriary
primary and secondary failed
- rehab
- livable life goal
External farm biosecurity
measure taken to prevent infectious disease from entering or leaving farm
Internal farm biosecurity
measures taken to stop the spread of a disease within the farm
biosecurity measures
- purchasing policy
- dirty and clean road
- vehicles entering and leaving farm
- people/visitors
- fodder and water
- equipment
- housing and management
- vermin and bird control
- monitoring animal health
- disposal of carcass (burying, composting, burning)
decontamination
Sterilization
Disinfection
Antisepsis
sterilization
kills everything
disinfection
less effective
eliminate many
antisepsis
application of liquid antimicrobial chemical to skin or living tissue to inhibit or destroy microorganisms
Veterinary standard precautions
- hand hygiene
- personal protective equipment
- physical restraints
- sharps safety
- surgery care and precautions
- decontamination and disposal of waster
- vaccine for zoonotic disease
Breaking the chain of infection
- reservoir neutralization
- reducing contact potential
- protection of portal of entry
- increasing host resistance
reservoir neutralization
test and slaughter
mass therapy
environment manipulation
increasing host resistance
- chemoprophylaxis
- immunization
- -where: endemic areas
- -when: season
- -who: population at risk
- -why: loss caused by disease greater than cost of immunization
parasitic diseases
taenia solium
giardia
taenia solium
porcine cysticercosis
human taeniasis
human cysticercosis
neurocysticercosis
Reservoir: primary-people intermediate-pigs
transmission: eat under cooked pork, contaminated feed for pigs
Prevention: meat inspection, cook properly
hygiene, sewage management, target reservoir
Giardiasis
Reservoir: many species
Transmission: consuming cysts, water most common, surface contamination of food
Prevention: water treatment, sewage treatment, wash or peel veggies and fruits
Viral diseases
rabies
hantavirus
Rabies
All reservoirs are vector but not all vectors are reservoirs
-surveillance
~reduce animal reservoir: vaccination of domestic and wild animal and control feral animal populations
~reduce human risk: post-exposure procedures, vaccinate at risk individuals, education to reduce exposure risk
hantavirus
rodents are the reservoir and usually asymptomatic
Transmission: aerosol and bite
fever, chills, myalgia, headache
Bacterial diseases
Anthrax
brucellosis
Anthrax
spore forming bacterium
affect most mammal species
cattle mainly
Post-mortem signs: blood not clotted, spores in blood on microscopy, rapid bloating, lack of rigor mortis, blood from orifices
Brucellosis
- brucella melitensis: most pathogenic for people
- brucella abortus: more pathogenic in people
Transmission: ingestion, mucous membrane exposure, or percutaneous inoculation
Prevent: eliminate animal reservoir
Vector Borne diseases
Borreliosis
West nile disease
Borreliosis
two groups: lyme disease type from hard ticks and relapsing fever type from soft ticks
avoid contact with ticks, tick repellants
west nile
maintained in a moquito-bird-mosquito cycle
Transmission: bite of infected mosquito
or blood borne infection, lab exposure and breast milk
most people are symptomatic
serovar
strain within a species with distincitive antigenic properties; further characterization of species
symbiosis
neutral, antagonistic or synergistic relationship between two dissimilar organisms living in close association with each other
mutualism
mutually beneficial relationship between two species (+/+)
commensalism
(+/0) relationship between two species in which one is benefited and the other is not affected
parasitism
(+/-) relationship between two species in which one benefits (parasite) from the other (host)
transient flora
microbial flora only temporarily occupying a given niche
niche
place of an organism within its community
microbial flora of the normal animal body
skin respiratory tract (nose, nasopharynx, mouth, oropharynx) eye and outer ear intestinal genitourinary tract
gram +
purple
gram -
pink/red
role of normal flora
common source of infection
immune stimulation
keeping out invaders
role in nutrition and metabolism
factors that control the growth of microorganisms
nutrient availability
physico/environmental parameters
competition
host immune system
fastidious
organism that has complex nutritional requirements
vector
a carrier, animal that transfers an infectious agent from one host to another
-arthropod
carrier
symptomless individual who is host to a pathogenic microorganism with the potential to pass pathogen to others
pathogenicity
quality of producing a disease or the ability to produce pathogenic changes or disease
virulence
measure of pathogenicity
how severe the disease is
epidemic
disease occurring suddenly in numbers clearly in access of normal expectancy
endemic
present in a population or geographic area at all times
pandemic
widespread epidemic distributes or occurring widely throughout a region, country, continent or globally
viruses can cross the blood brain barrier using what cells
monocytes
tropism
the specificity/affinity of a virus for a particular host tissue
pantropic viruses
can replicate in more than one host organ/tissue
teratogenic viruses
cause developmental defects of embryo or fetus after in-utero infection
LPS
from gram negative bacteria
amphophilic molecule found in outer bacterial membrane
receptor on macrophages
Lipid A is the toxic portion
Exotoxins
delivered to eukaryotic cell by secretion into surrounding environment or direct injection into cell
- enzymatic activity
- proteolytic break down of host proteins
- membrane disrupting toxins-pore formation
- toxins against IgA and host cytoskeleton
types of adhesins
polypeptides (proteins) or polysaccharides
protein adhesins can be fimbrial or afinbrial
-gram negative use fibriae
invasins
extracellular or intracellular
extra-uses enzymes which break down cell integrity of host allowing invasion of tissue
inra- obligate or facultative
sigma factors
mechanism of virulence regulation
protein subunits of RNA polymerases which control transcription
-bacteria use to control gene expression of virulence factors
horizontal gene transfer
molecular evolution of novel pathogens
donor to recipient
blocks of DNA which contain large mobile genetic components
pathogenicity islands
contain virulence factors like adhesins, invasins, toxins
different mechanisms bacteria use to resist antibiotics
- modification of antibiotic target sites
- alteration of antibiotic uptake
- inactivation of antibiotics
- can occur by deliberate gene transfer or spontaneous mutations
Protozoa
single celled, nucleated
multiply in hosts
classified by mode of locomotion by pseudopodia, flagella, cilia, gliding movements
helminths
worm like animal showing differentiation, metazoans
do not likely multiply in host
nematode
round worm
free-living
sexes separate
cestode
tape worm contain a scolex, flat body strobila with proglottids flat worms -segmented
trematode
fluke
flat worms look like a leaf
oral and ventral suckers
genetically independent
arthropods
arachnids (ticks, mites- 4 pairs of legs) and insects
-flies, fleas, lice, hemiptera (bed bugs) 3 pairs of legs
mosquito
ectoparasite
lives on the host
causes infestation
endoparasite
lives in the host
causes infections
definitive host
harbors adult stage of the parasite
intermediate host
harbors the larval stage of the parasite
incidental host
an unusual host, unneccessary for the maintenance of the parasite in nature
routes of parasite entry
- ingestion
- skin
- transplacental
- transmammary
- arthropod bite
- sexual contact
diagnostic tools/methods for parasites
host species
site of infection
size of parasite
As vets you should understand what about parasites
- taxonomic classification; scientific and common name
- host; zoonotic
- ID
- life cycle
- site of infection
- pathogenesis and lesions
- clinical signs
- diagnosis
- treatment and prevention
serology
detection of viral antigen or host antibody against virus
virus replication
attachment penetration uncoating synthesis of viral nucleic acid and protein assembly and maturation release in large numbers
vertical transmission
infection that is transferred from mother to embryo or fetus after parturition
ELISA
enzyme-linked immunosorbent assay
- direct
- indirect
- capture (sandwich)
PCR
polymerase chain reaction
electrophoresis
separated in electrophoretic field
negatively charged molecule–positive end mobility
depends on: size and structure
Restriction fragment length polymorphism
RFLP
requires restriction enzymes: cute DNA at or near specific recognition nucelotide sequences
–sticky end with overhang
–blunt end
example would be for forensic analysis and parent ID
hybridization
denatured, single-stranded DNA
- Dot
- in situ
- southern
- northern
- microarray
probe
- fragment of nucleic acids
- labeled, radiosotope, enzyme
- high degree of specificity
nucleic acid amplification
- signal: bDNA assays, hybrid capture assays
- target: enzyme mediated process to synthesize copies of targeted nucleic acid (PCR) & isothermal amplification like LAMP
- –high sensitivity and false positives
PCR primers
distance between the primer binding sites determines the size of the PCR product
-determine the specificity
Real-Time or Quantitative PCR
probe or dye to generate a fluorescent signal from the product
signal an exponential curve with a lag phase and a stationary phase
LAMP
loop-mediated isothermal amplification no thermal cycler needed quick, sensitivity higher than PCR visible results complicated design
silent mutation
mutations without apparent effect
-base change in DNA, no change in AA
Missense mutation
change in codon–change in AA–change in protein function
Nonsense mutation
change in coding codon to a termination codon, resulting premature termination
frameshift mutations
inserting or deleting number of bp other than a multiple of 3
transformation
acquisition of new genetic markers by incorportation of added DNA
conjunction
mating between two bacteria involving transfer of genetic material
transduction
transfer of bacterial gene from one to another by a phage
transposition
movement of a transposon to a new site in the genome
