, a

vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifi ...

against

Epstein–Barr virus The Epstein–Barr virus (EBV), also known as human herpesvirus 4 (HHV-4), is one of the nine known Herpesviridae#Human herpesvirus types, human herpesvirus types in the Herpesviridae, herpes family, and is one of the most common viruses in ...

was not yet available. The virus establishes latent infection and causes

infectious mononucleosis Infectious mononucleosis (IM, mono), also known as glandular fever, is an infection usually caused by the Epstein–Barr virus (EBV). Most people are infected by the virus as children, when the disease produces few or no symptoms. In young adu ...

. There is also increasingly more evidence that EBV may be a trigger of

multiple sclerosis Multiple sclerosis (MS) is an autoimmune disease resulting in damage to myelinthe insulating covers of nerve cellsin the brain and spinal cord. As a demyelinating disease, MS disrupts the nervous system's ability to Action potential, transmit ...

. It is a dual- tropic virus, meaning that it infects two different host cell types — in this case, both

B cell B cells, also known as B lymphocytes, are a type of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or inserted into the plasm ...

s and epithelial cells. One challenge is that the Epstein–Barr virus expresses very different proteins during its

lytic The lytic cycle ( ) is one of the two cycles of viral reproduction (referring to bacterial viruses or bacteriophages), the other being the lysogenic cycle. The lytic cycle results in the destruction of the infected cell and its membrane. Bact ...

and its latent phases. Antiviral agents act by inhibiting viral DNA replication, but , there was little evidence that they are effective against Epstein–Barr virus. They are also expensive, risk causing resistance to antiviral agents, and (in 1% to 10% of cases) can cause unpleasant

side effect In medicine, a side effect is an effect of the use of a medicinal drug or other treatment, usually adverse but sometimes beneficial, that is unintended. Herbal and traditional medicines also have side effects. A drug or procedure usually use ...

s. Several clinical trials for a vaccine were conducted in 2006–2008. The viral proteins Gp350/220 are a primary target, but this would only block infection of B cells, not epithelial cells. A vaccine called MVA-EL has been also proposed as a target for EBV-positive cancers, but this would only be effective in combating EBV-related cancers, not the EBV infection itself. VLP ( virus-like particle)-based EBV vaccines are also the subject of intensive research. In April 2018, the first human

antibody An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as pathogenic bacteria, bacteria and viruses, includin ...

that blocks Epstein-Barr Virus was discovered, called AMMO1. It blocks

glycoprotein Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...

s gH and gL. This discovery defines new sites of vulnerability on Epstein-Barr Virus, and neutralizes the dual-tropic infection (stopping both infection of B cells and epithelial cells). It is the most promising discovery to date, as it is the first that may be able to block both B cell infection and epithelial infection. In 2021,

Moderna Moderna, Inc. ( ) is an American pharmaceutical and biotechnology company based in Cambridge, Massachusetts, that focuses on RNA therapeutics, primarily mRNA vaccines. These vaccines use a copy of a molecule called messenger RNA (mRNA) to carry inst ...

announced two mRNA vaccine candidates targeting EBV: a prophylactic mRNA-1189 and a therapeutic mRNA-1195. Regarding the mRNA-1189, the company said that the "vaccine encodes five

s to inhibit both mechanisms for viral entry into B cells (gp350 plus gH/gL/gp42), adds protection for epithelial cells (gH/gL), and includes gB for protection of all cells." The viral proteins produced by the

mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein. mRNA is ...

in this vaccine are expressed in their native form, bound to the

cell membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...

, where they are available for recognition by the

immune system The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...

. The company began Phase I clinical trials of mRNA-1189 on 5 January 2022. The other candidate, mRNA-1195 vaccine, is being developed to prevent longer-term complications which may be caused by EBV, and it contains additional antigens compared to mRNA-1189. In early 2023, Moderna began Phase I clinical trials of mRNA-1195.

References

Vaccines Epstein–Barr virus {{vaccine-stub