Exam 3: Dr. Pinchuk Evasion and Subversion Flashcards
What is protective immunity to streptococcus pneumoniae like?
Serotype-specific
What does each stereotype of streptococcus pneumoniae cause?
A primary immune response
What is the most important source of long-term protective immunity to many infectious diseases?
Antibodies directed against macromolecules on the surface of pathogens
How do some species evade long-term protection?
By existing in numerous different strains, which differ in the antigenic macromolecules on their outer surfaces
What does mutation allow influenza virus to do?
Escape from immunity
What results in antigenic drift?
Point mutations in the hemagglutinin and neuraminidase viral genes
What does recombination allow influenza virus to do?
Escape from immunity
What is antigenic shift?
Appearance of the new antigens as a result genetic recombinations between two or more viral strains
What does antigenic variation by African trypanosomes allow them to do?
Escape from adaptive immunity
What uses persistence by hiding from the immune responses?
Herpesviruses persist in a latent state in the trigeminal region
Ncp BVDV
Look at sabotage or subversion of immune defense mechanisms
Look at sabotage or subversion of immune defense mechanisms
What are survival strategies of intracellular pathogens?
Interfere with antigen uptake mechanisms thus avoiding fast and effective antigen recognition
Create their own vesicle environment which prevents the binding to MHC and their presentation to T cells
Prevent fusion of the phagosomes with lysosomes thus protecting themselves from the lysosomal enzymes, survive and flourish within the cells of vesicular system
Escape from the phagosome into the cytosol, grow and replicate
What is toxoplasma gondii?
Highly successful obligate intracellular parasite that can invade and replicate in almost all nucleated cells of warm-blooded animals
What does toxoplasma gondii do?
Regulates immune activation and host cell effector mechanisms by specific parasite effector proteins
What are toxoplasma effectors?
Master regulators of the pro-inflammatory response
What do the combination of the effectors of toxoplasma gondii work to maintain?
An optional parasite burden in different hosts to ensure parasite transmission
What are the target cells for leishmania?
Macrophages
How are canine vector-borne diseases characterized by?
The unique three-way interaction between the infectious agent, the vector, and the host immune system
What do the effects on host immunity promote?
Th2 regulated humoral responses above the host protective Th1-regulated cellular response
What are the 2 types of immunity developed with leishmania?
Sterilizing immunity
Chronic infection
What is sterilizing immunity prevented by?
T cells with regulatory function
Look at leishmania picture
Look at leishmania picture
What do viral replication and life cycle depend on?
The metabolic and biosynthetic processes in the host cells
What are the viral self-defense strategies?
Capture of cellular genes encoding cytokines and receptors and diverting the immune response
Synthesis of proteins that inhibit complement fixation
Synthesis of proteins that inhibit antigen processing and presentation
What are the most powerful T cell mitogens ever discovered?
Superantigens
What do superantigens do?
Stimulate the T lymphocytes in an uncontrolled manner resulting in fever, shock, and death
What does T cells being activated by superantigens result in?
Massive systemic release of pro-inflammatory cytokines, such as TNF-α and IL-1β, and T cell mediators, such as IL-2m which can lead to fever and shock
Are superantigens presented as peptides in the peptide-biding groove of MHC II molecules?
No
What do superantigens bind to?
MHC II molecules without being processed previously
What happens in the superantigen mode of stimulation?
Does not prime an adaptive immune response specific for the antigen
Stimulates large numbers of T cells
Causes a massive production of cytokines by CD4 T cells
Contributes to microbial pathogenicity
What are examples of superantigen-mediated diseases?
Toxic shock syndrome
Food poisoning
Mastitis
Can immune responses contribute to disease?
Yes
For some infectious disease, what is all pathology due to?
Immune response
How do helminths go viral?
Cellular signals during helminth infections can skew the immune response to favor viral spreading
What does a helminth reaction activate?
Th2 cells to release IL-4 and IL-3
What does the ideal immune response do?
Terminates infection before the pathogen damages tissues or saps the body’s resources
What is the ideal situation for a pathogen?
The immune system does not interfere with growth and replication
Other parts of the body provide food and shelter
