**5. Conclusions**

In this study, we were able to validate the application potential of fluorescent TAP as a platform for viral immune evasion studies. Our results indicate TAP-GFP variants susceptible to BoHV-1 UL49.5-induced degradation, demonstrate that this degradation is p97-dependent, and emphasize the importance of linker design in fusion protein construction. The fluorescent TAP platform can be now applied in further research on BoHV-1 UL49.5, for instance in the genome-wide search for cellular proteins responsible for UL49.5-induced degradation, where the fluorescent signal can be measured and indicate even small changes in TAP levels. TAP-GFP could be also exploited to identify the active motifs or amino acid residues of UL49.5 affecting TAP stability. The same platform with viral inhibitors can be applied, in a similar way as in the study by [28], to identify TAP conformation recognized by UL49.5.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2073-4409/8/12/1590/s1. Figure S1: Comparison of GFP fluorescence of TAP-GFP variants in HEK293T cells; Figure S2: Susceptibility of TAP-GFP expressed in reconstituted U937 cells to UL49.5-mediated inhibition and degradation.

**Author Contributions:** Conceptualization, M.W. and A.D.L.; methodology, M.W. and A.D.L.; investigation, M.W., M.G., P.P., A.W.B., R.D.L., and A.D.L.; resources, A.D.L. and E.J.H.J.W.; writing—original draft preparation, A.D.L. and M.W.; writing—review and editing, A.D.L., P.P., K.B.-S., and E.J.H.J.W.; visualization, M.W. and A.D.L.; supervision, A.D.L., K.B.-S., and E.J.H.J.W.; project administration, A.D.L.; funding acquisition, P.P. and A.D.L.

**Funding:** This study was funded by Polish National Science Center, gran<sup>t</sup> number UMO-2014/14/E/NZ6/00164 to A.D.L. P.P. was funded by the European Commission under the Horizon2020 program H2020 MSCA-ITN GA 675278 EDGE.

**Acknowledgments:** We would like to thank Michał Rychłowski, Laboratory of Virus Molecular Biology, University of Gda ´nsk, Poland, for help with fluorescent confocal microscopy and Robert-Jan Lebbink, Department of Medical Microbiology, University Medical Center Utrecht, The Netherlands, for help in preparation of this manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
