Rubella Virus
A Viral Biorealm page on the Rubella Virus
Classification
Viruses; ssRNA viruses; ssRNA (+) viruses; Togavirdae; Rubivirus; Rubella Virus [NCBI]
Description and significance
The only member of the Rubivirus genus, Rubella Virus is only known to infect humans [Lee-Bowden] and is responsible for the common childhood disease known as German Measles or Three Day Measles.[CDC] The disease presents primarily as a skin rash with other mild symptoms in adults who contract the disease. [ADAM] Rubella can also cause arthritic symptoms, most commonly in women [Lee-Bowden] Rubella Virus can be prevented with the MMR (Measles, Mumps, Rubella) Vaccine which makes the virus uncommon in countries where vaccines are available. [Medline Plus] Rubella Virus can cause serious harm to unborn fetuses of mothers who contract Rubella Virus within the first trimester. The virus causes CRS (Congenital Rubella Syndrome) causing birth defects. CRS can cause a variety of birth defects and can lead to miscarraige or stillbirth. [Lee-Bowden]
Genome structure
The Rubella Virus genome is composed of 9757 nucleotides and has similar genomic structure to other Togaviruses. The Rubella Virus has the highest concentration of G/C nucleotides of any RNA virus with 69.5% of the genome consisting of those nucleotides. [Dominguez, Wang, Frey] Rubella has been sequenced completley for three strains shwoing >95% homology between the three strains. [Lee-Bowden]
Cell structure & life cycle
Rubella Virus is an enveloped virus, circular or oval in shape and 60nm in diameter. The viron is composed of a capsid core containing a single copy of genomic RNA. The outer membrane is a lipid bilayer containing specilized glycoproteins (E1 and E2) believed to be responsable for attachment to host cells. It is also believed that a pH of 6.0 or less induces conformational changes in the glycoproteins making attachment of the viral envelope to host cells more likely. Rubella virus likely enters cells via endocytosis. Once in the cell a conformational change occurs in the capsid shell releasing the genetic information into the cell. Replication is slow with a latency period of 8-12 hours, with structural proteins appearing at 12-16 hours and peak viral 36-48 hours after infection. In volenter subjects infected via aresol the characteristic rash typically appears 16-20 days from the time of exposure. [Lee-Bowden]
Pathogenesis
If it is a pathogen, how does this organism cause disease? Human, animal, plant hosts? Describe virulence factors and patient symptoms. Rubella virus only infects humans and is spread from person to person through contact or from a cough or sneaze as the rubella virus lives in the mucus of an infected person. The virus can be transmitted up to a week before the rash apeares and one to two weeks after. [ADAM] Rubella is also transmitted from an infected mother to her unborn child causing CRS. [CDC] Symptoms for postnatal Rubella virus include a rash spreading down from the face to the extremedies and in some cases a runny nose, fever or joint pain. It is possible for the virus to be asymptomatic. [Lee-Bowden] CRS causes a number of birth defects which include but are not limited to prenatal cataracs, deafness, low birth weight and mental retardation. [NYT] Rubella virus only has a large risk of infection if the disease is contracted by the mother in the first trimester, after which birth defects are less likely [Lee-Bowden]
Interesting feature
Describe in detail one particularly interesting aspect of your organism or it's affect on humans or the environment.
