Rubella, the infection formerly known as “German Measles,'' is caused by the Rubella virus.
Thanks to vaccination, it’s a disease we see less and less, although because some groups are under-immunized, it’s still possible to see outbreaks.
The Rubella virus is part of the Togaviridae family.
Togaviruses are single-strand RNA viruses surrounded by an icosahedral capsid, which is a spherical protein shell made up of 20 equilateral triangular faces, all within a spherical outer lipid envelope.
They’re also positive sense RNA viruses, which means that their genetic material is actually mRNA, so it can be used right away by the host cell to make viral proteins.
Now, the Rubella virus is transmitted through respiratory droplets, which are released into the environment when you sneeze or cough on another person.
Within the nasopharynx mucous membrane, the virus binds to a specific receptor on the membrane of epithelial cells.
It’s then surrounded by a little section of cell membrane that pinches off to form an endosome, that’s brought into the cell.
The low pH in the endosome uncoats the viral RNA and the virus causes changes to the endosome.
Now, when the Rubella virus enters the cell it also rearranges some of the organelles, gathering the endoplasmic reticulum, golgi apparatus, and mitochondria around the endosome.
The result is a membrane-bound Viral Replication Complex where - like the name says - the virus replicates.
So, after the virus replicates, its structural proteins are synthesized using the rough endoplasmic reticulum and these proteins are then transported to the golgi apparatus to be assembled and surrounded by membrane, a process called viral budding.
The new virus copy eventually exits the cell by exocytosis and enters nearby lymphatic and blood vessels, travelling to lymph nodes where it will replicate once again.
From the lymph nodes, it enters blood vessels again, and spreads to various parts of the body, making its way into various bodily fluids like urine, cerebrospinal fluid, and synovial fluid of joints.