Microbial methods Flashcards
3 features of the epidermis that lead to it being a good barrier to infection?
mechanical barrier, low pH, production of antimicrobial fatty acids/defensis
antimicrobial defensins are produced by which cell types?
epithelial cells in skin and mucosa
microbes “changing their coats” to evade immune cell recognition is called what?
antigenic variation
Does genetic rearrangement or genetic reassortment lead to antigenic shift?
reassortment leads to antigenic SHIFT, rearrangement (e.g. recombination, gene conversion, site-specific inversion) leads to antigenic drift
Protein A produced by S. aureus helps the organism do what?
evade phaocytosis by competitively binding to Fc portion of antibodies
chronic viral infections can lead to “t-cell exhaustion,” in part due to increased expression of which surface protein?
PD-1
a bacterial trait that allos them to turn on gene expression and express specific traits only when the organism grows to a high concentration is called what?
Quorum sensing
which receptor does lipoteichoic acid bind to?
TLR-2
bacterial toxins that stimulate a high number of T lymphocytes leading to massive T cell prolifeartion and potentially SIRS are called what?
superantigens
What are the 5 main types of functions provided two the infectious agent by virulence factors?
- Colonize (adhesins ) 2. Invade (invasins) 3. evade 4. suppress 5. acquire (siderophores)
Which cell in the GIT is not covered by mucus?
M-cells in Peyer’s patches
where in the GIT would you encounter follicle associated epithelium (FAE?)
Peyer’s patches
centrifugal turbulance is a physical barrier encountered in which portal of entry?
Respiratory
which three cell types are most often involved in “leukocyte trafficking” by infectious agents?
Macrophages/monocytes, lymphocytes, dendritic cells
what is the most common type of cell used as a target for microbes?
epithelial cells
what is the primary target of colonization and replication for Swine dysentery (B. hyodysenteriae)?
goblet cells of the colon and cecum
mucus is a strong chemoattractant for which types of bacteria?
spirochetes
what is the primary target of colonization for Mycoplasma hyopneumoniae, the causitive agent of porcine enzootic pneumonia?
Cilia
Which bacterial agent colonizes ciliated respiratory epithelial cells and uses neuraminidase to injure and destroy respiratory cilia?
Manheimia hemolytica
By which mechanism does lawsonia intracellularis enter the cells of the intestinal crypts?
endocytosis (phagocytosis) - escapes before phagosome-lysosome fusion occurs
which virus of pigs crosses the mucosal barrier by using M-cells?
Porcine circovirus type II - PMWS
receptor mediated endocytosis generally occurs on which cell surface? what about exocytosis?
endocytosis occurs on the apical surface, exocytosis occurs on the basolateral surface
which virulence factor does Leptospira use to penetrate endothelial cells and vascular walls?
invasive motility
parvovirus uses receptors expressed only on which cell surface to gain entry?
basolateral
influenza virus uses receptors expressed only on which cell surface to gain entry?
apical
sheep pox and goat pox viruses directly enter which cell type to gain entry to MALT?
dendritic cells
which bacterial disease of horses gains entry via leukocyte trafficking in mucosal associated macrophages?
R. equi
which viral disease of cattle gains entry via nerve endings and then spreads via retrograde axonal transport?
Bovine herpes virus 5
which bacterial pathogen of poultry utilizes galactosidases and glucosaminidases to reduce the viscosity of mucus making it less dense?
Necrotizing enteritis (Clostridium perfringes)
The genetic region in cattle called “BOLA” encodes which types of proteins related to immune responses?
MHC
epitheliogenesis imperfecta in horses, cattle, and pigs as well as primary ciliar dyskinesia in young dogs are both autosommal recessive hereditary diseases that increase susceptibility to infections due to decreased __________ function.
barrier
granulocytopathy is an autosomal recessive hereditary disease that leads to decreased levels of which molecule, leading to decreased ability of neutrophils to kill bacteria in the phagosome?
NADPH (leading to decreased hydrogen peroxide)
metabolic deragements in purine or pyrimidine metabolism may cause which leukocyte disorder in dogs?
cyclic hematopoeisis
which bacterium most often forms “grape like clusters” of cocci?
staphylococcus
which type of virulence factor inhibits biochemical pathways within a cell?
Exotoxins
which type of virulence factor stimulates macrophages and endothelial cells to secrete proinflammatory cytokines and NO to cause cell dysfunction and lysis?
Endotoxins
which type of virulence factor causes cell lysis?
hemolysins
how does Clostridium septicum penetrate the mucus layer?
it digests the mucus layer with enzymes and consumes it as a carbon source
Type P fimbria are used by which type of E coli?
Uropathogenic
K99 pilus adhesion is used by which type of E coli?
enterotoxic
Which type of bacteria utilizes an invasin that acts on actin filaments to promote its own endocytosis?
Listeria monocytogenes
which bacterium utilizes M protein and a hyaluronic acid capsule to evade immune recognition
Streptococcus pyogenes
which type of toxins are released from living bacteria?
exotoxins
lipoteichoic acid is released from which type of bacteria?
dead gram positive bacteria
endotoxins are released from which type of bacteria?
dead gram negative bacteria
which type of bacteria produces a diptheria-like toxin that inhibits protein synthesis?
Corynebacterium pseudotuberculosis
which type of bacteria produces heat labile and stabile enterotoxins that activate ion and water pumps?
Enterotoxigenic e coli
which type of bacterial toxin utilizes SNARE protein cleavage to inactivate selective proteins?
Tetanus and Botulism
in the A-B toxin system, which part binds to the receptor and which part enters the cytoplasm?
A enters cytoplasm, B binds receptor
Which parts of LPS are toxic? which are immunogenic?
The lipid A component is toxic, the polysaccharide component is immunogenic
E coli and salmonella use which type of secretion system?
Type III
what is the function of enterobactin, a virulence factor from E coli and salmonella?
siderophore - scavenges bound iron and makes it available for bacteria
clusters of genes that encode virulence factors are called what?
pathogenecity islands
the process by which bacteria pass genes to their “offspring” during DNA replication is called what?
vertical gene transfer
the process by which bacteria pass genes to other bacteria is called what? What are three ways they can do this?
Horizontal gene transfer - through conjugations with plasmids, transformation (DNA are taken up by viable bacteria), or bacteriophages (bacterial viruses)
which is the only strain of E coli to invade mucosal enterocytes to cause cell death and a malabsorptive diarrhea?
EHEC
which strain of E coli causes secretory diarrhea due to functional enterocyte disruption?
ETEC
which strain of E coli causes osmotic diarrhea due to structural enterocyte disruption?
EPEC
which strain of E coli causes “attaching and effacement” injury to the SI?
EPEC
which strain of E coli uses a type III secretion system to inject bacterial proteins (ESPA, ESPB, ESPD) into the enterocyte?
EPEC
verotoxin is a virulence factor utilized by which strains of E coli?
EPEC and EHEC
which strain of E coli uses Shiga toxins?
EHEC
what is the target cell for EHEC?
enterocytes of the colon
which strain of E coli can cause septicemic colibacillosis?
EPEC
paratyphoid nodules may be seen with infection with which bacterial species?
Salmonella
button ulcers are a lesion associated with the chronic form of which bacterial pathogen?
salmonella
The type I secretion system used by salmonella spp. has what effect on macrophages?
induces apoptosis due to caspase 1 activation
injestion of anti-trypsin in colostrum may increased the susceptibiliy to which bacterial disease?
Clostridium perfringes
which bacterial pathogen secretes exotoxins such as edema factor (EF) and lethal factor (LF)?
Bacillus anthracis
Which bacterial disease of horses uses virulence factors called “VAPs” to block phagosome lysosome fusion and then replicates in macrophages?
Rhodococcus equi
Which bacterial disease of cattle requires iron for growth inside the phagosome of tissue macrophages?
Mycobacterium avium ssp. pseudotuberculosis
What is the incubuation period of Johne’s disease?
> 12 months
Which bacterial disease of swine causes massive thickening of the mucosal surface of the GIT?
Lawsonia intracellularis
Which bacterial disease of swine infects mucinogen droplets within goblet cells of the cecum and colon?
Brachyspira hyodysenteriae
Which bacterium produces large quantities of phospholipase C (aka beta toxin or beta lechthinase) to cause hemolysis?
Clostridium hemolyticum
Which bacterial pathogen typically occurs after an animal has been infected with liver flukes?
Clostridium hemolyticum
fomites containing endospores much be less than what size in order to reach the gas exchange portion of the respiratory system?
5 um
Which bacterial respiratory pathogen utilizes the virulence factor “leukotoxin” in its pathogenesis?
Manheimia hemolytica
How does Manheimia hemolytica use neuraminidase in its pathogenesis?
Reduces the viscosity of mucus to allow the bacterium to access cell membranes via random brownian movement and reduces the net negative surface charge to allow closer contact of the bacteria with the cell
A dorsal diaphragmatic distribution pattern is seen in which porcine respiratory disease?
PRDC
APX toxin is synthesized and released by which respiratory pathogen of swine to cause lysis of the macrophage that it is replicating within?
Actinobacillus pleuropneumoniae
which two pathogens can cause atrophic rhinitis in swine?
Bordetella bronchiseptica and Pasteurella multocida
which bacterial pathogen of swine has virulence factors that include dermonecrotic toxin (DNT) and pertactin?
Bordetella bronchiseptica - Pasteurella multocida also has PMT toxin which is also a DNT
What do white spotted kidney disease (E. coli), embolic nephritis (actinobacillus equuli), bacterial hepatitis (E coli and fusobacterium necrophorum), and bacterial endocarditis (E. coli) have in common?
All cause embolic disease
what is the causitive agent of edema disease in pigs?
E coli
Which E coli strains produce verotoxin (Shiga toxin 2)?
Hemolytic strains
Pilli of UPEC strains bind to uroplakins expressed on which type of cell?
Specialized transitional epithelial cell (umbrella cell)
Name 4 virulence factors used by E coli in the pathogenesis of necrohemorrhagic cystitis
Capsular (K antigen), exotoxins (LT and ST toxins, shiga like toxin), P and S fimbriae for adhesion, siderophores
What is the target cell for renal leptospirosis?
proximal tubular epithelial cell
what is the causitive agent of contagious bovine pyelonephritis?
Corynebacterium, truperella, e coli
Which clostridial toxin is an important virulence factor in the pathogenesis of pulpy kidney disease?
E-toxin (pore forming permease)
Phospholipase D and mycolic acid are virulence factors of which bacterial agent? What are their functions?
Corynebacterium pseudotuberculoss - Phospholipase D increases vascular permeability to facilitate systemic spread (the bacteria replicates within macrohages), and it injures cell membranes leading to macrophage and neutrophil dysfunction. The mycolic acid is a waxy coating that induces inflammation and prevents phagosome-lysosome fusion.
which clostridium disrupts neurotransmitter release at myoneuronal junctions? which at neural-neural junctions?
Myoneuronal = botulinum, neural-neural = tetani
which clostridial toxin goes hematogenously and which goes via retrograde axonal transport?
botulinum = hematogenous, tetani = retrograde axonal transport
free tetanus toxin binds to the cell membrane of which type of neurons (inhibitory or excitatory?)
inhibitory
Disruption of the synaptic cleft fusion complex prevents release of which neurotramitters for botulism and tetanus?
Achetylcholine for botulism and GABA for tetanus
Where in the CNS does L monocytogenes localize to?
The brainstem
what is the function of the virulence factor listerolysin O?
immune evasion
which pathogen uses actin-based motility via virulence factor ActA?
Listeria
Which bacterial disease has been shown to activate bovine platelets and increase expression of adhesion molecules on endothelial cells - leading to activation of clotting cascades?
Thrombotic meningoencephalitis (Histophilus somni)
what is the causitive agent of focal symmetric encelphaomalacia in ruminants?
Clostridium perfringes
Edema disease is caused by which strain of E. coli?
Hemolytic strains
which bacterial disease of pigs leads to sebaceous gland hyperplasia?
Greasy pig disease (Staph hyicus)
Which type of virulence factor removes sialic acid from glycoproteins, glycolipids, and oligosaccharides, exposing new receptors for the bacterium?
Neuraminidase
In the context of viral disease, what is the difference between a susceptible cell and a permissive cell?
Susceptible cell is any cell a virus can infect, a permissive cell is any cell that a virus can infect and go through a full replicative cycle. Virus infected permissive cells are usually killed by the virus, whereas virus infected susceptible cells are usually not killed by the virus
what is the mechanism of cell death with parvo virus? what about distemper virus?
parvo = lysis distemper = apoptosis
Where are pox viral inclusion bodies found?
in the cytoplasm - even though they are a DNA virus
which genus of RNA viruses replicate in the nucleus?
Orthomyxoviruses
how are enveloped vs. non enveloped viruses released from the target cell?
non-enveloped released during cell lysis, enveloped released during budding
NSP4 is a viral toxin produced by which virus and secreted into the intestinal lumen causing secretory diarrhea?
Rotavirus
viroporins, endolysins, holins, and spanins are viral proteins that have what effect on cells?
Cause cell lysis
which type of virus (DNA or RNA) has a higher mutation rate?
RNA viruses
Which type of virus (DNA or RNA) has a faster replicative speed?
DNA viruses
in the context of viral pathogenesis, homologous crossing over that results in segmental genomic changes is called what?
Antigenic shift
which two processes can result in antigenic shift?
Recombination (in both DNA and RNA viruses) or reassortment (in RNA viruses only)
which process occurs when two or more different strains of the same segmented virus infect the same cell and then reassemble to form a new virus? which types of viruses can do this?
Reassortment
what are some ways in which interferon protects against viruses?
induces protein to block viral attachment, entry and disassemly, activates immune cells, promotes apoptotis of the target cell and cell-mediated immunity to kill target cell
ADD FLASHCARDS ABOUT VIRAL DISEASES
Which form of candida is pathogenic? the yeast or the hyphae/pseudohyphae?
hyphae/pseudohyphae
by which process do dimorphic fungi switch forms?
morphologic or phenotype switching
what is the main factor that influences whether candida are in the yeast or hyphal forms?
temp - RT (25C) = yeast, higher temp (37C)= hyphal BUT the yeast can switch this temperature dependence with chromosomal rearrangements and the hyphal form can grow at 25C
candida cell wall ligands such as AL and Hwp allow it to do what?
adhere to epithelial cells and invade mucosa
which virulence factor does the hyphal form of candida use to invade mucosa?
invasins
which fungal pathogen may result in epithelial hyperplasia and pseudomembrane formation?
candida
In dimorphic fungi, which form occurs in extracellular environments (25C) and which form occurs in intracellular environments (37C)?
mycelial (microconidial form) in 25C and yeast form in 37C
in dimorphic fungi, which form can be killed by macrophages/neutrophils?
the mycelial form
how does histoplasmosis prevent phagocytosis?
prevents acidification of the phagolysosome
what is the danger in culturing dimorphic fungi?
culturing conditions mimic environmental, not tissue/host conditions, so, when the organism grows, the form is infectious to people
what is the function of gliotoxin, fumagillin, verruculogen, and helvoilic acid produced by aspergillus conidia?
slow the beat of cilia in the mucociliary aparatus and injure ciliated mucosal epithelial cells
which aspergillus virulence factor is thought to be related to its ability to cause pulmonary disease?
biofilm formation
What are the purpose of fungal virulence factors such as B-glucans and melanin?
block killing by ROS
which fungal pathogen undergoes endosporulation?
coccidia
Match the mycelial phase (conidia, microconidia, arthroconidia, basidiospores) with the correct dimorphic fungal pathogen: Blasto, crypto, histoplasma, coccidioides
conidia (blasto), basidospores (crypto), arthroconidia (coccidioides), microconidia (histoplasma)
which dimorphic fungus uses urease to contribute to host tissue damage?
Coccidioides
BAD1 is an adhesion protein that allows which fungal pathogen to adhere to which macrophage receptor?
blastomyces adheres to CR3 and CD14 on alveolar macrophages
which fungal pathogen utilizes glucosylceramide synthase to survive in the mucosae
cryptococcus
which fungal virulence factor (utilized by blasto, cryptococcus and aspergillus) is an antioxidant and eliminates ROS?
melanin
what does cryptococcus use as a substrate for melanin production?
neurotransmitters
which protozoal pathogens have “gliding motility” ?
cryptosporidium, toxoplasma
Tissue tropism of coccidia species is determined by which surface proteins?
MICs
which protozoal pathogen has an adhesive disk?
Giardia
Variable small proteins (VSPs) are virulence factors of which protozoal pathogen?
Giardia
which protozal pathogen are the oocysts resistant to degradation and can survive years in the environment?
Toxo
What is the differerence between the oocysts shed by cryptosporidium and coccidia?
crypto oocysts are sporulated when they are shed and are immediately infections, coccidia need to sporulate in the environment
SAGs are ligands for adhesion on which protozoal parasite?
Toxoplasma
infection in early gestation with Toxoplasma would cause what clinical scenario?
Fetal lysis and resorption
infection in mid-gestation with toxoplasma would cause what clinical scenario?
fetal lysis and mummifaction - possible viable but weak fetuses
iinfection in late-gestation with toxoplasma would cause what clinical scenario?
no abortion - adaptive immunity
intracytoplasmic vacuoles in neurons nd neuropil are hallmark features of which etiologic agent?
prions
how to prion diseases get to the CNS?
retrograde axonal transport
