BIOL 22100 Midterm Exam III: Study Guide for Immunology, Pathogenicity, and Microbial Diseases

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Innate and Adaptive Immunity

Interferon Production and Function

Interferons are cytokines produced by host cells in response to viral infections and other pathogens. They play a crucial role in the innate immune response by interfering with viral replication and modulating the immune system.

Type I Interferons (IFN-α, IFN-β): Produced by most cells upon viral infection; bind to receptors and induce antiviral states in neighboring cells.
Type II Interferon (IFN-γ): Produced mainly by T cells and NK cells; activates macrophages and enhances antigen presentation.
Mechanism: Interferons stimulate the production of antiviral proteins and upregulate MHC expression.
Example: IFN-α is used therapeutically for hepatitis B and C infections.

Granuloma Formation

Granulomas are organized collections of immune cells formed in response to persistent pathogens or foreign substances. They are characteristic of chronic inflammatory diseases such as tuberculosis.

Components: Macrophages, T cells, fibroblasts, and multinucleated giant cells.
Function: Wall off pathogens that cannot be eliminated.
Exception: Granulomas do not typically include antibodies as a structural component.

Antibody Classes and Placental Transfer

Antibodies (immunoglobulins) are proteins produced by B cells that recognize and neutralize antigens. Different classes have distinct functions and properties.

IgG: The only antibody class that can cross the placenta to protect the fetus.
Other Classes: IgM, IgA, IgD, and IgE do not cross the placenta.
Example: Maternal IgG provides passive immunity to newborns.

Principles of Disease and Epidemiology

Autoimmune Diseases

Autoimmune diseases occur when the immune system mistakenly targets self-antigens, leading to tissue damage.

Lupus: Autoantibodies are directed against nuclear antigens such as DNA.
Example: Systemic lupus erythematosus (SLE) involves antibodies against double-stranded DNA.

Immunodeficiency Diseases

Immunodeficiencies result from defects in the immune system, leading to increased susceptibility to infections.

Common Variable Immunodeficiency (CVID): Characterized by low levels of immunoglobulins and recurrent infections.
Example: Patients with CVID often suffer from respiratory and gastrointestinal infections.

Microbial Mechanisms of Pathogenicity

Staphylococcal Protein A

Protein A is a virulence factor produced by Staphylococcus aureus that binds to the Fc region of IgG antibodies, interfering with opsonization and phagocytosis.

Function: Prevents effective immune clearance of the bacteria.
Example: Protein A contributes to the pathogenicity of S. aureus in skin and soft tissue infections.

Nosocomial Infections

Nosocomial (hospital-acquired) infections are infections acquired in healthcare settings. Prevention strategies are essential to reduce their incidence.

Prevention: Use of HEPA filters, hand hygiene, and patient isolation.
Example: MRSA outbreaks in hospitals can be controlled by strict infection control measures.

Microbial Growth and Control

Vaccines and Immunization

Vaccines stimulate the immune system to provide protection against infectious diseases. They can be live attenuated, inactivated, or subunit vaccines.

Live Attenuated Vaccines: Contain weakened pathogens; induce strong, long-lasting immunity.
Inactivated Vaccines: Contain killed pathogens; safer but may require boosters.
Subunit Vaccines: Contain purified antigens; used for diseases like pertussis (whooping cough).
Example: The acellular pertussis vaccine is currently used for whooping cough.

Antimicrobial Drugs

Antimicrobial drugs are used to treat infections by inhibiting or killing pathogens. The minimum inhibitory concentration (MIC) is a key parameter in determining drug efficacy.

MIC: The lowest concentration of an antimicrobial that inhibits visible growth of a microorganism.
Application: Used to guide antibiotic therapy in clinical settings.
Equation:

Microbial Genetics and Biotechnology

ELISA (Enzyme-Linked Immunosorbent Assay)

ELISA is a laboratory technique used to detect the presence of antibodies or antigens in a sample.

Direct ELISA: Detects antigens using a labeled antibody.
Indirect ELISA: Detects antibodies using an antigen-coated surface and a labeled secondary antibody.
Application: Used for diagnosis of infections and monitoring immune responses.

Viruses, Viroids, and Prions

Viral Structure and Classification

Viruses are acellular infectious agents composed of genetic material (DNA or RNA) surrounded by a protein coat (capsid). Some viruses have an envelope derived from host cell membranes.

Enveloped Viruses: Have a lipid bilayer envelope; often more sensitive to environmental conditions.
Non-enveloped Viruses: Lack an envelope; generally more resistant to desiccation and disinfectants.
Example: Influenza virus is an enveloped virus with a segmented RNA genome.

Viral Transmission and Disease

Viruses can be transmitted through various routes, including respiratory droplets, direct contact, and vertical transmission (mother to child).

Vertical Transmission: Example includes HIV transmission from mother to child during birth.
Common Childhood Diseases: Measles, mumps, and rubella are preventable by vaccination.

Tables

Antibody Classes and Properties

Antibody Class	Main Function	Placental Transfer
IgG	Opsonization, neutralization, complement activation	Yes
IgM	First antibody produced, complement activation	No
IgA	Mucosal immunity	No
IgE	Allergic responses, defense against parasites	No
IgD	B cell receptor	No

Types of Vaccines

Type	Example	Advantages	Disadvantages
Live Attenuated	MMR (measles, mumps, rubella)	Strong, long-lasting immunity	Risk in immunocompromised patients
Inactivated	Polio (Salk vaccine)	Safe for immunocompromised	May require boosters
Subunit	Pertussis (acellular)	Fewer side effects	Less immunogenic

Additional info:

Some context and explanations have been expanded for clarity and completeness.
Topics covered align with chapters on immunity, microbial pathogenicity, vaccines, and microbial genetics.