6.2 Replication

Flashcards covering the viral replication cycle, modes of viral entry and release, viral tropism, host cell utilization, and types of viral infections (acute vs persistent chronic/latent) based on Chapter 1-8 of the lecture transcript.

Viral replication

The process where a virus utilizes host cell supplies and machinery (such as amino acids, nucleotides, enzymes, and organelles) to reproduce and make virions.

Attachment

The first step of animal virus replication where capsid proteins (for naked viruses) or spike proteins (for enveloped viruses) bind to target proteins on host cells.

Entry

The second step of viral replication in which the viral genome enters the host cell.

Uncoating

The third step of viral replication where the capsid breaks down to release viral proteins and genome into the host cell's cytoplasm.

Replication step

The fourth step of viral replication involving synthesis of the viral genome, transcription into messenger RNA, and translation into viral proteins.

Assembly

The fifth step of viral replication where viral components are put together, placing a capsid around the viral genome and necessary enzymes.

Release

The sixth and final step of viral replication where newly formed virions exit the host cell either by budding off or lysing the cell.

Capsid proteins

Proteins of the capsomeres in a naked virus that bind directly to host cell membranes during attachment.

Spike proteins

Proteins located on an enveloped virus that recognize and bind to specific target proteins on host cells.

Endocytosis

A mechanism of viral entry used by both enveloped and naked viruses where receptor binding causes the host cell to engulf the virion into a vesicle.

Membrane fusion

An entry mechanism used by enveloped viruses where the viral envelope fuses directly with the host cell's plasma membrane.

Direct entry

A third mechanism of viral entry used specifically by bacteriophages to inject their genome into prokaryotic cells.

Tropism

The specificity of a virus to attach to and infect specific host cells or tissues.

Narrow tropism

A property of viruses that limits their binding to only a specific type of cell or tissue within a host.

Hepatotropic virus

An example of a virus with narrow tropism that can only target host liver tissue.

Broad tropism

A property of viruses allowing them to attach to and infect multiple cell types or tissues within a host.

Ebola

An example of a virus with broad tropism that can attach to and infect multiple cell types and tissues.

Capsomere

Protein components making up the viral capsid that assist naked viruses in binding to host membranes.

Endocytic vesicle

A cell vesicle holding an engulfed virion, inside of which cellular enzymes break down the viral capsid during uncoating.

DNA virus replication location

Process in which viral DNA enters the nucleus to replicate and transcribe into mRNA, which is then translated into proteins in the cytoplasm.

RNA virus replication location

Process in which viral RNA is replicated and translated directly in the cytoplasm of the host cell.

Retrovirus replication location

Process conducted inside the nucleus by retroviruses (such as HIV) using reverse transcriptase and host genome integration.

Acute infection

An infection where the virus immediately replicates upon cell entry, developing and resolving quickly as the immune system clears it.

Common cold

A classic example of an acute viral infection that develops and resolves quickly.

Persistent infection

A long-lasting infection (chronic or latent) where replication cycles differ and can persist in the host for months up to a lifetime.

Latent persistent infection

An infection where replication peaks and decreases, but the immune system cannot clear it, causing the virus to persist in the body.

Quiet periods

Time intervals during persistent infections when virion replication remains very low.

Chronic persistent infection

An infection where virion replication remains low initially—allowing host infectivity unnoticed—before ramping up years later.

T lymphocytes

Host white blood cells targeted and destroyed by HIV when virion replication ramps up years after initial infection.

Provirus

Viral DNA integrated into the host cell's genome that may remain dormant, silent, or produce low levels of virions.

HPV (Human Papillomavirus)

A persistent virus that acts as a provirus and can lead to cervical and head and neck cancers.

Host cell resources

Cellular components including amino acids, nucleotides, enzymes, and organelles hijacked by viruses to build virions.

Prokaryotic cell host

The cellular host type infected specifically by bacteriophages via direct entry.

Cytoplasmic uncoating

The breakdown of a viral capsid by cytoplasmic enzymes to release viral contents into the cytoplasm following entry.

Nuclear uncoating

A process used by certain DNA viruses where uncoating is delayed until the capsid enters the nucleus for transcription and translation.

Cervical cancer

A type of cancer that can result from persistent provirus infection by Human Papillomavirus (HPV).

Head and neck cancers

Types of cancer associated with persistent provirus infection by Human Papillomavirus (HPV).

Integrating enzymes

Enzymes in retroviruses like HIV that assist in integrating reverse-transcribed viral DNA into the host cell's genome.