latent virus infection

please give me information about latent virus infection

In latent infections, overt disease is not produced, but the virus is not eradicated. This equilibrium between host and parasite is achieved in various ways by different parasites and hosts. The virus may exist in a truly latent noninfectious occult form, possibly as an integrated genome or an episomal agent, or as an infectious and continuously replicating agent, termed a persistent viral infection.

Infectious agents causing chronic persistent infections have found a way of escaping a cell-mediated immune response. The mechanisms include

1. generation of cells that escape a cell-mediated immune response.
2. down regulation of MHC production in infected cells so that they are not recognized and destroyed by T cells.
3. infection of cells in immunoprivileged sites such as the brain.

Examples of latent infection include

1. Chronic Congenital Rubella, CMV, EBV, hepatitis B, HIV
2. Latent HSV, VZV, adenovirus and some retroviral infections
3. SSPE, PML, Kuru, CJD, progressive rubella panencephalitis