Evolution, Viruses, and HIV — Vocabulary

Vocabulary flashcards covering key terms from the lecture on HIV, viruses, zoonotic transmission, evolution by natural selection, and antiviral strategies.

Evolution by natural selection

The process by which heritable variation leads to differential survival and reproduction under environmental conditions, causing adaptation over generations.

HIV (human immunodeficiency virus)

The retrovirus that attacks the human immune system, primarily CD4+ T cells, and can lead to AIDS if untreated.

AIDS

Acquired immunodeficiency syndrome; the advanced stage of HIV infection with severely weakened immune function.

Zoonotic disease

A disease that originated in animals and has crossed the species barrier to infect humans.

Spillover event

Transmission of a pathogen from one species to another, often via close contact or crossover of host barriers.

Reservoir host

The species in which a pathogen is maintained in nature, typically with less severe disease, and from which it can spread to new hosts.

SIV (simian immunodeficiency virus)

A family of immunodeficiency viruses in nonhuman primates; closely related to HIV and the likely source of HIV via spillover.

Phylogenetic tree

A diagram showing evolutionary relationships among organisms or viruses; used to infer origins and relatedness (e.g., HIV and SIV).

Reverse transcription

The process by which retroviruses convert their RNA genome into DNA inside a host cell.

Reverse transcriptase

The viral enzyme that carries out reverse transcription in HIV; lacks proofreading, contributing to a high mutation rate.

Integrase

The HIV enzyme that integrates viral DNA into the host cell’s genome.

Central dogma of molecular biology

Idea that genetic information typically flows DNA -> RNA -> protein; retroviruses reverse-transcribe RNA into DNA, partially bypassing this flow.

Retrovirus

A virus with an RNA genome that uses reverse transcription to form DNA inside a host cell.

Virion

The extracellular, infectious particle of a virus circulating outside cells.

Obligate parasite

An organism that cannot replicate without a host cell; viruses are obligate parasites.

AZT (azidothymidine)

The first antiretroviral drug; a nucleoside analog that inhibits reverse transcription and can lead to resistance over time.

Drug resistance

The ability of a pathogen to survive and continue replicating despite drug therapy, often via mutations and selection.

Mutation

A random change in a genetic sequence; the source of genetic variation.

Mutation rate

The frequency at which mutations occur during replication; HIV has a high mutation rate due to lack of proofreading in reverse transcription.

Drug cocktail

A combination of multiple antiretroviral drugs targeting different stages of the viral life cycle to reduce drug resistance.

Fitness

A measure of reproductive success; in HIV, resistant variants may have higher fitness under drug pressure.

Ecological niche

The set of host cells or environments a virus uses; for HIV, T cells are a key niche within the human body.