Rubella Antibodies, Proteins & ELISA Kits

Rubella, commonly known as German Measles, is a disease caused by the single-stranded positive sense rubella virus, which belongs to the Rubivirus genus and the Togaviridae family. Humans are the only reservoir for rubella virus and the route of transmission is through aerosol secretions from the respiratory tract of infected individuals.

The main symptoms for rubella are malaise, low-grade fever, sore throat, headaches, anorexia, lymphadenopathy and exanthem, which is characterized by the development of rashes and papules. Typically people who are infected with rubella experience mild symptoms. However, when rubella virus infects a pregnant woman, especially during the first trimester, it can lead to congenital rubella syndrome (CRS) and miscarriages.

The number of rubella cases has decreased dramatically over the years due to the emergence of live-attenuated vaccines, such as the measles, mumps and rubella (MMR) vaccine. Rubella is a candidate for eradication through vaccine prevention strategies due to humans being the viral host. However, there are still roughly 100,000 rubella cases reported worldwide annually, demonstrating the need for further research in order to continue with the enhancement and development of rubella vaccines.

Rubella virus has two non-structural proteins; p90 and p150. In addition, rubella virus has three structural proteins; capsid proteins (C) and envelope glycoproteins E1 and E2. The C proteins surround the viral RNA and regulates viral replication. E1 and E2 are both synthesized as a polyprotein precursor and they are needed for viral virulence. In particular, E1 is the major target antigen of rubella virus and it is required for receptor binding, receptor-mediated endocytosis and the induction of membrane. The function of E2 is not entirely clear but it has been shown that E2 has strain-specific epitopes and a neutralizing domain and when E2 is absent, E1 has been shown to be arrested in the pre-Golgi complex compartment.

Rubella virus E1 protein binds to the myelin oligodendrocyte glycoprotein (MOG) which is a type I integral membrane protein. MOG is believed to share structural similarities with rubella virus E2 protein and some studies have shown the effectiveness of blocking MOG binding sites with antibodies for the purpose of preventing rubella virus binding. While MOG is the only known rubella virus receptor, researchers are currently trying to identify other possible receptors which may be involved in viral cell entry.

A key area of research is the immune response against rubella virus. There have been numerous studies which have examined the humoral response against rubella virus in individuals who have received their second MMR vaccination. Firstly, the humoral response consisted of an initial low affinity level of immunoglobulin M (IgM), with transient peaks of both IgG3 and IgA being observed shortly after IgM production. IgG1 was the main antibody involved in the immune response against rubella virus.

The cellular response against rubella virus in individuals who had received their MMR vaccination was also analyzed and high levels of pro-inflammatory cytokines were observed. Interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF-alpha) were the main pro-inflammatory cytokines which were produced.

There have also been conflicting results whereby some studies have examined high levels of IL-10 and others have only observed minimal quantities of IL-10. A synergistic relationship between interferon-gamma (IFN-gamma) and the humoral response was also identified and the main overall observation of the studies was that rubella virus triggered the secretion of Th-1 response cytokines more strongly than Th-2.

Many of the functional capacities of a cell are dependent on the metabolic state of the cell and its capability to perform functions. Studies have been conducted to investigate how rubella infections affect host cell metabolism. It has been shown that there is an increase in oxidative phosphorylation (OXPHOS), glycolysis and alanine synthesis during rubella infections. In particular, the C protein of rubella virus localizes to the mitochondria whereby it associates with p32 and this allows the virus to ensure there is a constant supply of adenosine triphosphate (ATP) for viral replication. As well as this, rubella infections result in an increase in the respiratory chain (RC) complexes II and III but a decrease in complex IV. These alterations of the electron transport chain (ETC) by rubella virus are not associated with the induction of oxidative stress and it may be carried out by the virus to avoid triggering danger-associated metabolic modifications (DAMM).

Humans are the only known reservoir for rubella virus. However, mice models have been used to study rubella virus pathogenesis and they are extensively used for vaccine research and development. In particular, the Th1 cytokine skewing which was observed in humans was also observed in mice for rubella virus.

As well as this, there has been the identification of relatives of rubella virus such as ruhugu virus (RuhV) and rustrela virus (RusV). These relatives affect a wide range of animals such as donkeys and bats and they may be useful for furthering rubella virus research and for undertaking comparative studies.