Long Latent Phase Of EBV Infection Is The Key To The Success Of Pathogen

Epstein-Barr virus has three latency programs (called latency stages 1 to 3) in its life cycle. Different viral genes are turned off at each stage. Latency program 0 possibly exists when all genes are turned off. Switching off the viral genes helps the virus to stay undetected and avoid elimination by the host immune system.

In the latent (dormant) form the virus stays in the epithelial cells in the throat or in the B cells of immune system. B cells with latent virus reside mostly in the bone marrow. Virus doesn’t multiply when it is in latent stage.

The limited gene expression is an important feature of latency stage in which the virus expresses only very few proteins thus minimizing the chances of being recognized by immune system. This feature is the major reason why virus is so widespread in human population.

Reactivation of virus

To ensure the viral spread and survival, the latent virus in B cells must be awakened, re-enter lytic phase and invade new epithelial cells.

In B cells, lytic replication usually takes place only upon reactivation of dormant virus. The exact mechanism of reactivation is still unknown. It is likely that reactivation happens in response to other infections. Reactivation is often asymptomatic. Some research data suggest that reactivation of virus can avoid the attention of immune system. Reactivation in response to other infections also plays its role in avoidance of immune response. Immune system is often weakened when other infections take place.

Diagnosis of EBV infection, its treatment and prevention

The presence of EBV can be detected using antibodies against various viral proteins. None of the existing methods, unfortunately, seem to guarantee the 100% accuracy of detection. New detection techniques are being developed using different EBV specific antigens.

Taking into account how widespread the EBV is, the prevention of infection is almost impossible. Currently there are no antiviral drugs available to treat the infection. The treatment of people with infectious mononucleosis is limited to the management of symptoms. No vaccine preventing the infection is available so far, but it is being currently developed.

Effective treatment of EBV infection needs to be developed

Epstein Barr virus is one of the most successful viruses in human population infecting overwhelming majority of people worldwide. Fortunately, the manifestations of the initial disease, infectious mononucleosis, are mild and the infection rarely causes complications. The association of virus with more severe illnesses such as some autoimmune diseases and some types of cancer calls for development of effective treatment and prevention strategy against EBV.

In recent years, the EBV has found a new application as a very good vector for gene therapy. The virus can be used to bring the desirable genes to the cells of the body. The applications of EBV based vectors for cancer therapy are particularly promising.