A Systematic Analysis of Host Factors Reveals a Med23-Interferon-? Regulatory Axis against Herpes Simplex Virus Type 1 Replication

Griffiths, Samantha J.; Koegl, Manfred; Boutell, Chris; Zenner, Helen L.; Crump, Colin M.; Pica, Francesca; Gonzalez, Orland; Friedel, Caroline C.; Barry, Gerald; Martin, Kim; Craigon, Marie H.; Chen, Rui; Kaza, Lakshmi N.; Fossum, Even; Fazakerley, John K.; Efstathiou, Stacey; Volpi, Antonio; Zimmer, Ralf; Ghazal, Peter; Haas, Jürgen

By nature of their scale, high-throughput screening technologies have limitations. RNAi technology is limited by technical issues such as off-target effects, where an alternative gene to the intended target is degraded, and insufficient gene knockdown. Similarly, Y2H protein interaction screens can generate both false-positive interactions, due to 'sticky' proteins and auto-activation of the reporter gene used, and false-negative interactions. Whereas the number of false positives can be considerably reduced by stringent screening and selection criteria, the low sensitivity of the Y2H assay, which detects 20-30% of known interactions, is inherent to the system and can only be marginally improved. This poor sensitivity is caused by factors such as structural restraints of the Y2H bait and prey fusion proteins, a lack of or existence of distinct protein modification in yeast cells, and cellular localization signals in bait and prey proteins preventing nuclear import [52] . However, as all other high-throughput methods for measuring binary protein interactions possess a similarly low sensitivity, but are considerably more laborious and expensive, the Y2H system is still the most commonly used technology [53] .