Positive-sense single-stranded RNA virus facts for kids

A positive-sense single-stranded RNA virus (often called a (+)ssRNA virus) is a type of virus. These viruses carry their genetic instructions using a special molecule called RNA. Think of RNA as a blueprint for making new viruses.

The "positive-sense" part means their RNA blueprint can be directly read by a host cell (like one of your cells!) to make proteins. These proteins are the building blocks and tools the virus needs to copy itself and spread. It's like the virus hands over its blueprint, and your cell immediately starts building from it.

Many common viruses are positive-sense RNA viruses. This group includes the viruses that cause the common cold (called rhinoviruses), Hepatitis C, West Nile virus, and dengue fever. More serious ones include the SARS and MERS coronaviruses, and SARS-CoV-2 which causes COVID-19.

What Are Viruses?

A virus is a tiny microorganism that can only grow and reproduce inside the living cells of other organisms. Viruses are much smaller than bacteria and cannot survive on their own. They are like tiny invaders that hijack a cell's machinery to make more copies of themselves.

How (+)ssRNA Viruses Work

These viruses have a single strand of RNA as their genetic material. This RNA is "positive-sense," meaning it's ready to be used right away by the host cell.

Entering the Cell

First, the virus attaches to a host cell and injects its RNA into it. It's like a tiny key fitting into a lock on the cell's surface.

Making Proteins

Once inside, the virus's positive-sense RNA acts like a messenger RNA (mRNA). This is the same type of RNA your cells use to carry instructions from your DNA to make proteins. The host cell's own machinery, called ribosomes, reads the viral RNA. It then starts building viral proteins.

Copying the RNA

Some of these newly made viral proteins are special enzymes. These enzymes help the virus make many copies of its own RNA. This process creates new viral blueprints.

Assembling New Viruses

Finally, the new viral RNA copies and proteins come together. They assemble into brand new virus particles. These new viruses then leave the host cell, often destroying it in the process, and go on to infect other cells.

Examples of (+)ssRNA Viruses

Many well-known viruses belong to this group. They cause a wide range of diseases, from mild to very serious.

Common Cold Viruses

Rhinoviruses are a common type of (+)ssRNA virus. They are responsible for most cases of the common cold. These viruses usually cause mild symptoms like a runny nose, sore throat, and sneezing.

Hepatitis C Virus

The Hepatitis C virus is another (+)ssRNA virus. It infects the liver and can cause a long-term (chronic) infection. This can lead to serious liver damage over time.

Dengue and West Nile Viruses

The dengue virus and West Nile virus are spread by mosquitoes. They can cause fever, headaches, and body aches. In some cases, they can lead to more severe illness.

Coronaviruses

Coronaviruses are a family of (+)ssRNA viruses. This family includes the viruses that cause SARS, MERS, and SARS-CoV-2 (which causes COVID-19). These viruses can cause respiratory illnesses, ranging from mild to severe.

Images for kids

• 

  Mechanisms of replicative and nonreplicative RNA recombination.

• 

  Phylogenetic tree with phylum branches highlighted. Negarnaviricota (brown), Duplornaviricota (green), Kitrinoviricota (pink), Pisuviricota (blue), and Lenarviricota (yellow).

• 

  False-color Transmission electron micrograph of a SARS-CoV-2 virion. Coronaviruses like SARS-CoV-2 fall in the phylum Pisuviricota.

See also

In Spanish: Virus ARN monocatenario positivo para niños