Table 1.

Viral immune evasion strategies through downregulation of innate and adaptive components of host cell immunity

evasion strategy	Possible mechanisms	Examples	References
RNAi	Encodes suppressors for RNA silencing (SRS) to inhibit RNAi responses	Ebolavirus	[43]
Inhibition of TAP, Tapasin and disruption of MHC-I	Post-translational strategies inhibiting peptide transport and MHC-I biosynthesis by blocking peptide transporter (TAP) and chaperones like tapasin	HCMV	[58]
	Viral proteins, BNLF2a and mK3 inhibit TAP associated MHC-I response by targeting host tail-anchored protein integration machinery and regulating ubiquitination of TAP/tapasin, respectively.	EBV, HSV-1, BHV-1,GHV	[64, 90]
	Viral proteins like UL49.5 and US6 alter the conformation, degrade the TAP1/2 interfere with ATP binding. HSV ICP47 protein interferes with peptide binding.	PRV, HCMV HSV	[3, 51, 61, 63, 65, 76, 78, 82]
LANA1 mediated evasion	Inhibits the presentation of Major Histocompatibility complex class I (MHC-I)	KSHV, EBV	[80]
IRF3 production	Inhibits IFN-γ and CIITA and thus MHC-I expression.	KSHV	[125]
Nef proteins	Nef proteins down-regulate MHC-I presentation of viral peptides.	SIV, HIV	[83, 96, 109, 145]
Viral NLR homolog	Homolog inhibits the inflammasome and also block caspase-1 activation, IL-1β and IL-18 processing	KSHV	[55]
	Impairs RIG-I-like receptor-dependent signaling inhibiting IFN and TNF-α.	HCV	[88]
Encoding VP35 proteins PRR control	TLRs and RLRs are taken into virus control of PRR signaling and regulation of immune programs	EBV	[84]
Inactivating MDA5	MDA5 is a cytosolic PRR that is inactivated.	Paramyxovirus	[111]
NF-κB suppression	Prevents NF-κB dependent gene expression by retaining p65 in cytoplasm when V protein binds to p65 (RelA)	Measles virus	[128]
Proteases targeting signal transduction	Block IFN induction by affecting molecules of the innate immune pathways	HAV, HCV	[110]
Degradation of cellular TRIF	Replication and transcription activator (RTA) degrades TRIF	KSHV	[2]
CD1d down regulation	Viral protein E5 targets CD1d (a sentinel molecule bridging innate and adaptive immunity) by inhibiting calnexin-related CD1d trafficking	HPV	[97]