Host and viral factors that influence viral neurotropism I. Viral cell attachment proteins and target cell receptors

Since the time of Charcot, over a century ago, it has been recognized that the clinical signs and symptoms produced by viral illnesses involving the CNS are due in large part to the specific regions of the nervous system injured. As the list of viruses capable of infecting the CNS expanded rapidly during the earlier part of the 20th century, so too did the recognition that individual viruses exhibited specific affinities for particular regions of the nervous system, and often for particular cell types within these regions. In this part of our review we will focus specifically on the role played by the interaction between specific viral proteins (‘cell attachment proteins’) and receptors on target cells in determining the tropism of certain viruses for the CNS. In a subsequent article, the role of host genes, the site of entry and route of spread of virus, and the contribution of tissue-specific viral genes (enhancers) to viral neurotropism will be reviewed.