Lecture 13 Flashcards
A genomic island that increases the “fitness” of a microorganism is called a(n) ____.
A) plasmid gene
B) pathogenicity island
C) phage gene
D) secretion system
B) pathogenicity island
____ move whole blocks of DNA from one organism to another.
Horizontal gene transfers
If the genomic island increases the “fitness” of a microorganism during interaction with a host, it is called a ____.
pathogenicity island
Which of the following is NOT a feature of a pathogenicity island?
A) They can be acquired through horizontal gene transmission.
B) They don’t confer fitness to the pathogen.
C) They are flanked by plasmid or phage sequences.
D) The ratio of GC/AT is different in the islands vs. the genome.
B) They don’t confer fitness to the pathogen.
Pathogenecity islands are acquired through ____.
horizontal gene transmission
Because the pathogenecity island is different, the ___ sequence is different from the genome.
GC/AT
The pathogenicity island is flanked by ____.
plasmid or phage sequences
All of the following are used for microbial attachment EXCEPT _____.
A) capsids
B) pili
C) fimbriae
D) ribosomes
D) ribosomes
Examples of microbial attachments
Capsids, envelopes, pili, and fimbriae
Exotoxins target all of the following EXCEPT _____.
A) vesicular trafficking
B) cytoskeleton alteration
C) protein synthesis
D) DNA synthesis
D) DNA synthesis
8 categories of microbial exotoxins
plasma membrane disruption,
cytoskeleton alterations
protein synthesis disruption
cell cycle disruption
signal transduction disruption
cell-cell adhesion disruption
vesicular trafficking
exocytosis
All of the following are methods intracellular pathogens can use to survive inside a host cell EXCEPT _____.
A) create a capsule.
B) escape the phagosome.
C) survive in the phagolysosome.
D) prevent phagosome-lysosome fusion
A) create a capsule.
Once inside the phagosome, intracellular pathogens have three options to avoid being killed by the phagolysosome:
survive in a phagolysosome
prevent phagosome-lysosome fusion
escape the phagosome
Protozoan antigenic variation causes the host’s immune system to continually make______.
A) macrophages
B) T-cells
C) NK cells
D) antibodies
D) antibodies
Switching to a new VSG (antigenic variation) allows the pathogen to avoid the ____ and is allowed to produce more ____.
antibody response; organisms
Small genetic changes to a virus that result in viruses with similar antigenic properties is called _____.
A) antigenic drift
B) antigenic shift
C) toxin production
D) antigenic variation
A) antigenic drift
All of the following are methods protozoans use to avoid the host immune response EXCEPT ____.
A) antigenic masking
B) toxin production
C) antigenic variation
D) immunosuppression
B) toxin production
Protozoans lack potent ___.
toxins
Protozoan immune-avoidance strategies include (4):
antigenic masking
antigenic variation
intracellular location
immunosuppression
Genomic island
a horizontally acquired region of the bacterial chromosome that has an altered GC content and segments of phages or plasmid DNA that mark it as different from the rest of the genome
Pathogenicity island
a genomic island that contains virulence factors that increase the fitness of the organism in the host
Capsule
coat bacterial cell walls and can prevent phagocytes from binding
Cell-surface proteins are components of the cell wall that ____.
prevent detection
Quorum sensing
used to communicate with other pathogens about population size
Antigenic variation
100 known serotypes of rhinovirus; each virus has a unique capsid protein. Antibodies to one capsid protein are not effective on another
Antigenic shift
Two strains of influenza virus infect the same cell and the genomes get mixed. This makes a dramatically different virus
Antigenic drift
Random mutations can occur within the cell that a virus infects creating small changes in virus proteins
Antigenic Masking
Some protozoans coat themselves in host antigens to avoid detection by the immune system
Antigenic Variation
Just like viruses and bacteria, some protozoans can alter their surface antigens to prevent antibody binding
Intracellular Location
Just like some bacteria, protozoans have found ways to live inside the host cell to prevent detection
Immunosuppression
Some protozoans induce the secretion of anti-inflammatory cytokines to reduce the innate immune response
____ contribute to a pathogen’s ability to cause disease.
Virulence factors
____ and ____ allow pathogens to invade host tissue and cause tissue damage
Exoenzymes; toxins
____ is the lipid A component of the LPS of the gram-negative cell envelope.
Endotoxin
____ are proteins secreted mainly by gram-positive bacteria, but also are secreted by gram-negative bacteria
Exotoxins
Bacterial pathogens may evade the host immune response by producing ____ to avoid phagocytosis.
capsules
Viral pathogens use ____ for initiating infections and antigenic variation to avoid immune defenses.
adhesins
Influenza viruses use both ____ and ____ to avoid being recognized by the immune system.
antigenic drift; antigenic shift
Fungal and parasitic pathogens use pathogenic mechanisms and virulence factors that are similar to those of ____ pathogens.
bacterial
____ initiate infections through the interaction of adhesins with receptors on host cells.
Fungi
____ are able to avoid the immune system by coating their exteriors with glycan molecules that make them look like host cells or by suppressing the immune system.
Helminthic worms
Which of the following is a major virulence factor for the fungal pathogen Cryptococcus?
A) hemolysin
B) capsule
C) collagenase
D) fimbriae
B) capsule
Phospholipases are enzymes that do which of the following?
A) degrade antibodies
B) promote pathogen spread through connective tissue.
C) degrade nucleic acid to promote spread of pathogen
D) degrade cell membranes to allow pathogens to escape phagosomes
D) degrade cell membranes to allow pathogens to escape phagosomes
Which of the following applies to hyaluronidase?
A) It acts as a spreading factor.
B) It promotes blood clotting.
C) It is an example of an adhesin.
D) It is produced by immune cells to target pathogens.
A) It acts as a spreading factor.
You have recently identified a new toxin. It is produced by a gram-negative bacterium. It is composed mostly of protein, has high toxicity, and is not heat stable. You also discover that it targets liver cells. Based on these characteristics, how would you classify this toxin?
A) superantigen
B) endotoxin
C) exotoxin
D) leukocidin
C) exotoxin
Which of the following would be a virulence factor of a pathogen?
A) a surface protein allowing the pathogen to bind to host cells
B) a secondary host the pathogen can infect
C) a surface protein the host immune system recognizes
D) the ability to form a provirus
A) a surface protein allowing the pathogen to bind to host cells
Which of the following choices lists the steps of pathogenesis in the correct order?
A) invasion, infection, adhesion, exposure
B) adhesion, exposure, infection, invasion
C) exposure, adhesion, invasion, infection
D) disease, infection, exposure, invasion
C) exposure, adhesion, invasion, infection
Antigenic _____ is the result of re-assortment of genes responsible for the production of influenza virus spike proteins between different virus particles while in the same host, whereas antigenic _____ is the result of point mutations in the spike proteins.
shift; drift
Adhesins are usually located on _____ of the pathogen and are composed mainly of _____ and _____.
surface; proteins; sugars
The glycoprotein adhesion gp120 on HIV must interact with ______ on some immune cells as the first step in the process of infecting the cell.
CD4
Cilia, fimbriae, and pili are all examples of structures used by microbes for _____.
adhesion
A(n) ______ pathogen causes disease only when conditions are favorable for the microorganism because of transfer to an inappropriate body site or weakened immunity in an individual.
opportunistic
Viruses are generally ultramicroscopic, typically from __ nm to __ nm in length. Some large viruses have been found.
20; 900
____ are acellular and consist of a nucleic acid, DNA or RNA, but not both, surrounded by a protein ____.
Virions; capsid
____ are obligate intracellular parasites
Viruses
Viruses typically have limited ____ and infect specific cell types.
host ranges
The component(s) of a virus that is/are extended from the envelope for attachment is/are the:
A) capsomeres
B) spikes
C) nucleic acid
D) viral whiskers
B) spikes
Which of the following does a virus lack? Select all that apply.
A) ribosomes
B) metabolic processes
C) nucleic acid
D) glycoprotein
A) ribosomes
B) metabolic processes
The envelope of a virus is derived from the host’s:
A) nucleic acids
B) membrane structures
C) cytoplasm
D) genome
B) membrane structures
What is another name for a nonenveloped virus?
A) enveloped virus
B) provirus
C) naked virus
D) latent virus
C) naked virus
Which of the following leads to the destruction of the host cells?
A) lysogenic cycle
B) lytic cycle
C) prophage
D) temperate phage
B) lytic cycle
A virus obtains its envelope during which of the following phases?
A) attachment
B) penetration
C) assembly
D) release
D) release
Steps of pathogenesis
Entry
Tissue attachment and colonization
Immune avoidance
Host damage
Pathogen exit
Genomic island
a horizontally acquired region of the bacterial chromosome that has an altered GC content and segments of phages or plasmid DNA that mark it as different from the rest of the genome
Pathogenicity island
a genomic island that contains virulence factors that increase the fitness of the organism in the host.
Adhesin
any microbial factor that promotes attachment
3 features of pathogenicity islands:
1) G/C content is different than the rest of the chromosome.
2) Islands are flanked by phage or plasmid genes.
3) Increase the fitness of the organism
3 types of EXOtoxins:
1) Two-Subunit AB
2) Membrane disrupting
3) Superantigens
The General Secretion Pathway secretes ____.
virulence factors
Type II secretion uses:
Pili to force protein through an outer pore.
Type III secretion is like a ____.
syringe
3 methods of intracellular escape:
1) Survive in phagolysosome
2) Prevent phagosome-lysosome fusion
3) Escape from phagosome
3 methods of extracellular immune avoidance:
1) Capsules
2) Antigenic variation
3) Quorum sensing
