Bacterial and Viral Virulence Factors

These flashcards cover key vocabulary associated with bacterial and viral virulence factors, their mechanisms, and their implications in immune response evasion.

Virulence factor

A molecule produced by a microorganism that allows it to colonize, infect, invade host cells, and evade the immune response, resulting in disease.

Bacterial capsule

A layer of polysaccharides and proteins surrounding the outer membrane of some bacterial cells that helps bacteria evade phagocytosis by masking its antigens.

Antigenic variation

The alteration of surface proteins that allows pathogens to avoid detection by memory T and B cells, enabling persistence of infection.

Viral adhesin

A protein or glycoprotein that binds to specific cellular receptors on the host cell, determining the tropism of the virus.

Tropism

The specific cell types or tissues that a virus can infect based on cell-specific receptors and viral adhesins.

Antigenic drift

Small mutations in viral surface proteins that allow a virus to partially evade established immune responses.

Antigenic shift

A major change in viral surface proteins that occurs when multiple viruses infect the same cell and exchange genetic material.

Coagulase

An enzyme that converts fibrinogen to fibrin, inducing clot formation around bacteria to protect them from the immune system.

Kinases

Enzymes that break down blood clots to release bacteria and connective tissue, facilitating bacterial invasion.

Proteases

Enzymes that degrade proteins, including antibodies and cytokines, thus helping pathogens resist immune defenses.

Phospholipases

Enzymes that degrade the membrane of phagosomes, allowing pathogens to escape and multiply inside macrophages.

VlsE antigenic variation system

A mechanism that allows Borrelia burgdorferi to maintain a long-term infection by altering amino acid sequences of its surface-exposed epitopes.