The studies described above indicate the advances made in the isolation and characterization of virus receptors of lymphoreticular cells (Table I). Although the examples of lymphotropic virus receptors cited in this chapter indicate that single membrane glycoproteins can serve as receptors, other nonlymphoid viruses such as vesicular stomatitis virus (VSV) (Table I) appear to utilize glycolipid or phospholipid components for cell attachment. These molecules may be responsible for the broad specificity of host cell attachment by these viruses. The virus-binding moiety of phospholipid/glycolipid receptors remains to be fully analyzed. It is anticipated that biochemical techniques such as the use of chemical cross-linking reagents will aid in the identification of other virus receptors such as CMV and measles which have less restricted lymphotropism than EBV. In addition, X-ray crystallographic analysis of viruses such as the recent studies of human rhinovirus and poliovirus may provide insights on the complementary structure of cellular recognition sites for viruses.