The identification and functions of host proteins in viral particles is an important step toward the elucidation of novel host-pathogen interactions. In the case of herpesvirions, this is well under way with eight different family members analyzed so far. One main aspect is to sort biologically relevant cellular proteins from sticky contaminants. The orthogonal validation of the host proteins found in herpesvirions using biologically relevant assays is thus critical. As pointed out above, it will necessary to analyze all these proteins in the background of two pools, one cellular and one virion-associated, which are likely to complement one another. An interesting possibility is that some isoforms or specific posttranslationally modified host proteins may be loaded into the capsids. Thus a detailed analysis of the host proteins present in viral particles will be important and a potential way to distinguish them from their cell-associated counterparts. Another issue is the expected variation among cell types. In that respect, it would be most interesting to examine the cellular protein content of HSV-1 produced in neurons in opposition to the virions produced on other cell types. Finally, the mechanisms by which all these host proteins are recruited to the viral particles will also need to be explored. Thus the proteomics of viral particles is only the beginning of the adventure, which should prove most exciting yet challenging.