Unit 04: Influenza A - Biology, Evolution, and Immune Response

A set of flashcards covering the core concepts of influenza biology, including viral structure, reproduction cycles, vaccine production methods, mechanisms of evolution, and the human immune response.

Influenza virus

A type of virus responsible for the respiratory illness known as the flu, classified into types A, B, C, and D, with A and B being most prevalent in humans.

Capsid

The protein coat that surrounds a virus's genetic material, potentially featuring spikes or tail fibers that assist in host cell attachment.

Envelope

The outer layer found in some viruses, such as influenza, composed of remnants of the host cell's plasma membrane to aid in cell entry.

Quadrivalent vaccine

A type of influenza vaccine designed to provide protection against four different versions of the virus.

Aluminum salts

An ingredient added to some vaccines to enhance the immune system's ability to detect the viral presence.

Lytic cycle

A viral reproduction pathway where the virus immediately uses host cell resources to manufacture and release new viruses, often causing the host cell to burst.

Lysogenic cycle

A viral life cycle involves the integration of viral DNA into the host genome, remaining latent until triggered to enter the lytic cycle.

Epithelial cells

The specific type of cells lining the respiratory system that serve as the primary targets for influenza virus infection.

Evolution

One of the unifying theories of biology, describing the process by which populations change over time through heritable changes in DNA.

Natural selection

The mechanism of evolutionary change proposed by Darwin and Wallace, involving variation, competition, and differential fitness within a population.

Fitness

A term used in biology to describe an individual's reproductive success.

Stabilizing selection

A form of natural selection that favors the average or most common variant of a trait while selecting against extremes.

Directional selection

Natural selection that favors variants at one extreme of a trait's distribution, causing the population to shift in that direction over time.

Disruptive selection

Selection that favors both extreme forms of a trait over the average or most common form.

Mutation

A change in the nucleotide sequence of DNA that can result in changes to protein properties and serves as a source of genetic variation.

Transitional fossils

Intermediate forms in the fossil record, such as Tiktaalik roseae or Archaeopteryx, that provide evidence of descent with modification.

Analogous structures

Structures that evolved independently to serve similar functions, such as the wings of birds and insects.

Homologous structures

Physical features shared by different species due to inheritance from a common ancestor, such as limb bone structures in mammals.

Antigenic drift

A process of viral evolution characterized by small, gradual mutations in the surface spikes of the influenza virus.

Antigenic shift

A significant evolutionary event where two different versions of a virus infect the same cell, leading to new combinations of surface spikes.

Lymphatic system

A system involved in returning tissue fluids to the circulatory system and housing core components of the immune response.

MHC markers

Major-histocompatibility complexes located on the plasma membrane that allow the immune system to distinguish 'self' from 'non-self' cells.

Antigen

Any substance, typically a protein or carbohydrate on a pathogen, that triggers a specific immune response from the body.

Innate defenses

Nonspecific immune mechanisms, including physical barriers like the skin and chemical signals like cytokines, that provide general protection.

Cytokines

Small protein chemical signals, such as histamine or interferon, that regulate local immune responses and can induce systemic symptoms like fever.

Inflammatory response

A nonspecific defense involving the release of histamine, increased blood flow, and the recruitment of phagocytes to a site of injury or infection.

Adaptive immunity

A specific immune response that targets particular antigens and develops memory for faster reactions upon future exposures.

Cell-mediated immunity

A branch of adaptive immunity using T lymphocytes to target and destroy host cells that have been infected by pathogens.

Antibody-mediated immunity

A branch of adaptive immunity where B lymphocytes produce antibodies to target free-floating pathogens in body fluids.

Recombinant process

A modern, rapid vaccine production method that uses only the H spike protein of the virus rather than the whole virus.

Giant viruses

A group of viruses, such as Mimivirus, that are significantly larger than typical viruses and challenge traditional definitions of life.

Formaldehyde

A vaccine component used to inactivate toxins from viruses or bacteria that may be present during the manufacturing process.

Thiomersal

A preservative often found in multi-dose vials of vaccines to prevent contamination.

Red bone marrow

The tissue responsible for producing lymphocyte cells and acting as the site where B lymphocytes mature.

Thymus

The organ where T lymphocytes mature and develop their specific antigen receptors.