Viral infections of the developing nervous system

Both clinical and experimental studies indicate that viruses can interact with the developing nervous system to produce a spectrum of neurological damage and brain malformations. Following infection of the pregnant woman, virus may indirectly or directly involve the fetus. Direct involvement is generally due to transplacental passage of the virus and invasion of fetal tissue. Resultant disease is determined by a variety of virus-host factors, including the developmental stage of the fetus at the time it is infected, the neural cell populations which are susceptible to infection, the consequent virus-infected cell interactions, and the mechanism and timing of viral clearance. There is a growing list of human viruses which injure the developing nervous system. There are also several experimental models in which congenital viral infections have been shown to result in a variety of brain malformations but with no evidence of the prior infection remaining at the time of birth.