Rubella virus is the cause of congenital rubella syndrome when infection occurs during the first weeks of pregnancy. Humans are the only known host of this virus. It is the only member of the genus of Rubivirus and belongs to the family of Togaviridae.
Members of the Togaviridae family typically have a genome of single-stranded RNA of positive polarity which is enclosed by an icosahedral capsid. This genome has a length of about 9,757 nucleotides and encodes for two non-structural as well as three structural proteins.
The molecular basis for the causation of congenital rubella syndrome is not completely clear. To replicate they attach to the cell surface though specific receptors and are taken up by an endosome being formed. Once the capsid reaches the cytosol it decays and releases the virus genome.