Definition

Noun: 1. A hypothetical infectious agent: In microbiology, a virino is a theoretical particle proposed to be the cause of certain degenerative brain diseases, such as scrapie in sheep. It is conceptualized as being composed of nucleic acid (which carries genetic information) surrounded by a protective coat made from the host organism's own proteins.

Usage Notes

• The term virino is used almost exclusively in specialized scientific contexts, particularly in microbiology, prion biology, and veterinary pathology.
• It describes a hypothetical model for an infectious agent. This model was proposed to explain diseases now widely attributed to prions. Therefore, in modern literature, the term "prion" is far more common.
• It is a countable noun (e.g., , ).

Examples

• The virino hypothesis suggested that the infectious agent for scrapie was smaller than a virus.
• Scientists debated whether the pathogen was a virino or a more conventional virus.
• This model proposed that the virino's protective coat was derived from host proteins.

Advanced Usage

• The virino concept was historically significant as a scientific model that attempted to explain the unusual properties of transmissible spongiform encephalopathies (TSEs) before the prion theory gained dominance.

Variants and Related Words

• Prion (n.): The currently accepted term for the infectious protein particle that causes diseases like scrapie, Creutzfeldt-Jakob Disease (CJD), and bovine spongiform encephalopathy (BSE/mad cow disease). A prion is defined as a misfolded protein that can induce normal proteins to also misfold.
• Viroid (n.): An infectious agent of plants, consisting solely of a short strand of circular RNA without a protein coat. It is distinct from a virino.

Synonyms

• Hypothetical infectious particle
• (Historical) Scrapie agent model

Word Origin and Notes

• Origin: The word virino is a modern scientific blend, likely formed from vir(us) + -ino (a diminutive or related suffix, as in ). It implies a particle smaller than or related to a virus.
• Important Note: The virino is a superseded theoretical concept. Contemporary science attributes the diseases it sought to explain to prions, which are infectious proteins lacking nucleic acid, a key difference from the virino model which included nucleic acid.

Noun

1. (microbiology) a hypothetical infectious particle thought to be the cause of scrapie and other degenerative diseases of the central nervous system; consists of nucleic acid in a protective coat of host cell proteins