Lectures 3 & 4: Overview of Immune Responses to Infectious Diseases Flashcards
What are general considerations in vaccine development?
- Infection extracellular or intracellular
- How is infection acquired?
- What immune effector functions are required for control and/or clearance?
- What evasion mechanisms are utilized by the infectious agent to subvert host immunity?
Are viral infections intra or extracellular?
Viral infections produce their antigens intracellularly, although many antigens are externally exposed.
Are bacterial and protozoal infections intra or extracellular?
They may be intracellular or extracellular, depending on species.
Are parasitic worm infections intra or extracellular?
They are almost always extracellular.
What are the antibody-mediated effector responses?
- Neutralization
- Opsonization of antigens or cells via FcR
- Complement activation
- Antibody-Dependent Cellular Cytotoxicity
- Mast cell degranulation
What are the cell-mediated effector responses?
- Phagocytosis
- Cytotoxic T-Cells
- Natural Killer Cells
- NKT Cells
- Delayed-Type Hypersensitivity
- Antibody-Dependent Cellular Cytotoxicity
What is the structure of a simple virus?
- An outer coat containing multiple copies of a protein required to bind to a host-cell receptor
- An inner core containing DNA or RNA (encode essential proteins)
What are examples of genes encoded by viruses?
Polymerase, other enzymes, regulatory/evasion proteins, core proteins, and surface proteins
What are the immune responses against viruses?
- Innate mechanism
- Antibodies & complement
- Th1-dependent cellular responses
- CTLs
Define antigenic drift.
The accumulation of point mutations eventually yields a variant protein that is no longer recognized by antibody to the original antigen.
Define antigenic shift.
May occur by reassortment of the entire ssRNA between human and animal virions infecting the same cell.
What allows antigenic shift in the influenza virus?
The segmented genome
What is the pathology of diphtheria?
It is mediated by a secreted exotoxin, once it is internalized, toxin interferes with protein synthesis and a single toxin molecule may kill a cell.
How can diphtheria be treated or prevented?
- Treatment by passive immunization with antitoxin
- Active immunization of inactivated toxoid, which retains the protective epitopes but cannot cause disease.
How do bacteria evade host defenses?
- Enhance adhesion to host cells
- Inhibition of phagocytosis
- Targeting of antibodies
- Antigenic variation
- Inhibition of complement
- Survival within phagocytic cells
