Reoviridae

Common Name

Reoviruses

Overview

Reoviridae is a family of double-stranded RNA viruses that can infect a wide range of hosts, including humans, animals, plants, and fungi. The name Reoviridae is derived from "Respiratory Enteric Orphan viruses" because they were originally believed to cause respiratory and enteric infections in humans without any known clinical effects. However, it is now understood that some of these viruses can cause significant diseases.

Taxonomy

Key Characteristics

  • Genome : Double-stranded RNA
  • Capsid Structure : Icosahedral, with two concentric layers of protein shell
  • Size : 60-85 nm in diameter
  • Hosts : Wide range of hosts including humans, animals, plants, and fungi

Life Cycle

  1. Attachment and Entry : Virus attaches to the host cell's surface receptors and is engulfed by endocytosis.
  2. Uncoating : Partial uncoating of the outer capsid occurs to release the core particle within the host cell.
  3. Replication and Transcription : Viral RNA-dependent RNA polymerase transcribes the dsRNA genome into mRNA within the core particle.
  4. Protein Synthesis : Host ribosomes translate viral mRNA to produce viral proteins.
  5. Assembly : New viral particles are assembled in the host cytoplasm.
  6. Release : Newly formed virions are released either by cell lysis or budding.

Behavior and Ecology

  • Transmission : Can be transmitted via respiratory droplets, fecal-oral route, direct contact, and vectors such as ticks and mosquitoes.
  • Reservoirs : Includes various animal species, with some specific viruses infecting plants and fungi.
  • Environmental Stability : Highly stable in the environment, resistant to proteases and low pH.

Notable Species

  • Rotavirus : Causes severe gastroenteritis in young children.
  • Bluetongue virus : Affects ruminants, causing significant economic losses in livestock.
  • Orthoreovirus : Generally causes mild respiratory or gastrointestinal symptoms in mammals.
  • Fijivirus : Infects plants, leading to diseases in crops such as rice and maize.

Conservation

There are no specific conservation efforts focused on the Reoviridae family, but significant attention is given to controlling the diseases they cause, especially in agriculture and public health.

Significance to Humans

  • Human Health : Rotavirus is a major cause of severe diarrhea in young children worldwide, leading to a significant number of hospitalizations and deaths.
  • Agriculture : Viruses like Bluetongue virus and Fijivirus have substantial impacts on livestock and crop production.
  • Research : Reoviruses are used in research to study virus-host interactions, cellular entry mechanisms, and vaccine development.

Fun Facts

  • Some reoviruses can be used as oncolytic agents to selectively kill cancer cells.
  • Rotavirus vaccines have dramatically reduced the incidence of severe gastroenteritis in children globally.
  • The name "Reovirus" means "respiratory enteric orphan virus" because they were initially thought to cause no disease in humans.
  • Reoviruses have been found in a wide range of environments, from the gut of animals to plant surfaces.
  • Bluetongue virus infections in livestock can lead to the production of deformed offspring, known as "dummy calves."