One aspect where the incorporation of host proteins in mature virions might be beneficial is molecules involved in intracellular trafficking. Work by numerous laboratories demonstrated that the transport machinery used to move cellular proteins is also employed by viruses (Simons and Warren, 1984; Lodish et al., 2000; Sollner, 2004; Greber and Way, 2006; Mercer et al., 2010) . This is essential for their proteins and particles to reach their final destination, for example, the site of viral replication, assembly, and/or envelopment. Along with SNARES proteins, Rab and Arf GTPases are master regulators of molecular trafficking throughout the cell (Sollner and Rothman, 1996; Zerial and McBride, 2001; Mizuno-Yamasaki et al., 2012) . So far,VAMP3, a SNARE, was identified in PRV virions (Kramer et al., 2011) but it may only be a matter of time until other SNARES are discovered in other members of the herpes family. This is relevant as another SNARE was reported to facilitate the envelopment of MCMV capsids (Cepeda and Fraile-Ramos, 2011) . In contrast, a great number of Rab proteins have been identified in herpesvirions, particularly HSV-1 and PRV (Table 1) . One stimulating option is that these proteins regulate the displacement of viral capsids in the cell, which could justify their incorporation in the viral particles. As Rab and Arf proteins collectively modulate several intracellular transport steps within the cell, it is anticipated they may be involved in various stages of the infection. For instance, Rab1, which is present in HSV-1 extracellular virions (Loret et al., 2008) , and Rab43 were recently demonstrated to modulate the final envelopment of the virus (Zenner et al., 2011) . Similarly, Rab6, found in HSV-1 and PRV (Loret et al., 2008; Kramer et al., 2011) , is also necessary for the efficient assembly of the related HCMV (Indran and Britt, 2011) . It will now be of interest to determine if the virion-associated pool of these GTPases actively participates in the viral life cycle. Interestingly, several Rab proteins have been implicated in autophagosome formation and maturation (Chua et al., 2011) . While it is difficult to consider how virion-incorporated Rab proteins play a role at that stage, they might rather be incorporated into the virions as MCMV FIGURE 1 | The proteins from Table 1 were analyzed with the Ingenuity database to define their putative functions in the context of an infection.