Host and viral factors that influence viral neurotropism II. Viral genes, host genes, site of entry and route of spread of virus

In the previous article in this series, we focused on how the interaction between viral cell attachment proteins and receptor molecules on the surface of host target cells played a major role in determining the cell and tissue tropism of many neurotropic viruses. In order to complete our review of viral factors that influence the tropism of viruses for the CNS, we will discuss the role of viral genes that function to specifically enhance the replication of viral proteins in certain cells or tissues (“tissue-specific enhancers and promoters”). We will then examine the ways in which host factors, including specific host genes, can influence resistance or susceptibility to certain types of neurotropic viral infections. Finally, we will conclude by reviewing how factors that involve the interaction of the host and the virus, such as the site of the viral entry and its route and method of spread, can influence the distribution of viral infection within the CNS.