Viruses, Viroids, and Prions

Comprehensive vocabulary flashcards covering the characteristics, taxonomy, life cycles, and pathogenicity of viruses, viroids, and prions as presented in the lecture notes.

Obligatory Intracellular Parasites

Organisms that require living host cells to live and multiply.

Capsid

A protein coat that contains the virus's genetic material (either DNA or RNA).

Envelope

An additional layer sometimes found around the capsid of a virus.

Polyhedral Virus

A virus shape composed of genetic material surrounded by a many-sided capsid, typically with 20 triangular faces.

Spherical Virus

Helical viruses enclosed in an envelope membrane spiked with sugary proteins that assist in sticking to and entering host cells.

Helical Virus

A virus with a slinky-shaped capsid that twists around and encloses its genetic material.

Complex Virus

A virus composed of a polyhedral "head," a helical body ("tail sheath"), and legs ("tail fibers") used to attach to a cell membrane.

Poliovirus Size

$$30\,\text{nm}$$

Ebola virus Size

$$970\,\text{nm}$$

-viridae

The suffix used for naming viral families.

Viral Species

A group of viruses sharing the same genetic information and ecological niche (host).

Alpha (B.1.1.7)

A COVID-19 Variant of Concern first detected in Kent, United Kingdom, in September 2020.

Delta (B.1.617.2)

A COVID-19 Variant of Concern that emerged in Maharashtra, India, in late 2020.

Incubation Period

The duration from initial exposure to the virus until the appearance of symptoms.

Latent Period

The duration from exposure until the person becomes infectious.

Period of Communicability/Infectious Stage

The time after exposure during which an individual can transmit the virus to others.

Bacteriophage

A virus that specifically targets and attacks bacteria, literally meaning "bacteria eater."

Plaques

Clearings on a lawn of bacteria on the surface of agar, where each clearing corresponds to a single virus.

Plaque-forming units (PFU)

The unit of measurement used to express the quantity of viruses based on the number of plaques formed.

Cytopathic Effect (CPE)

The deterioration of host cells in a culture caused by viral infection.

Lytic Cycle

A viral replication cycle where the virus enters the host cell and immediately makes copies, leading to cell lysis and death; described as an "Armed Robbery."

Lysogenic Cycle

A cycle where the virus integrates its DNA into the host's DNA and remains hidden for generations; described as a "Sleeper Agent."

Sarcoma

Cancer of the connective tissue.

Adenocarcinomas

Cancers of the glandular epithelial tissue.

Oncogenes

Genes that transform normal cells into cancerous cells.

Tumor-specific transplantation antigen (TSTA)

An antigen found on the surface of a cell that has been transformed into a tumor cell.

Epstein-Barr virus

A DNA oncogenic virus belonging to the Herpesviridae family (Human herpesvirus 4).

Latent Viral Infection

An infection where the virus remains asymptomatic in the host for long periods, such as Cold Sores or Shingles.

Persistent Viral Infection

An infection that occurs gradually over a long period and is generally fatal, such as Subacute sclerosing panencephalitis (Measles virus).

Viroids

Short pieces of naked RNA without a capsid that cause diseases like Potato Spindle Tuber Disease.

Virusoids

Viroids enclosed in a protein coat that only cause disease when the plant cell is coinfected with another virus.

Prions

Proteinaceous infectious particles caused by misfolded proteins ($PrP^{Sc}$) that lead to neurodegenerative diseases.

Creutzfeldt-Jakob Disease (CJD)

A 100% fatal prion disease that causes the brain to shrink and fill with sponge-like holes, resulting in loss of thought, movement, and memory.