Table 1.
Non-essential genes of HSV-1, corresponding proteins, their location on the HSV-1 virion, and their function. Pink: tegument proteins, blue: accessory proteins, yellow: envelope proteins, green: capsid proteins.
| Gene | Protein | Location on Virion | Function |
|---|---|---|---|
| RL1 or γ134.5 | ICP34.5 | tegument | Prevents host translational shutoff and autophagy |
| RL2 or α0 | ICP0 | tegument | Promiscuous transactivator of genes, disrupts repressor complexes, E3 ubiquitin ligase, inhibits innate immunity, modulates endocytosis, etc. |
| UL2 | uracil-DNA glycosylase | accessory | nucleic acid metabolism |
| UL3 | accessory | ||
| UL4 | accessory | ||
| UL7 | tegument | Virion assembly and egress | |
| UL10 | gM | envelope | Host and viral protein trafficking |
| UL11 | tegument | Cytoplasmic envelopment | |
| UL12 | accessory | Nucleic acid metabolism | |
| UL12.5 | accessory | Involved in depleting mtDNA | |
| UL13 | Ser/thr protein kinase | tegument | Blocking innate immune responses, supporting viral protein synthesis |
| UL16 | tegument | Cytoplasmic envelopment | |
| UL20 | envelope | Glycoprotein trafficking | |
| UL21 | tegument | Promotes capsid egress to the cytoplasm | |
| UL23 | thymidine kinase (TK) | tegument | Broad spectrum nucleoside kinase |
| UL24 | accessory | Glycoprotein trafficking, nucleolus dispersal | |
| UL31 | accessory | Component of the nuclear egress complex (NEC), promotes primary nuclear envelopment | |
| UL34 | accessory | Component of the nuclear egress complex (NEC), promotes primary nuclear envelopment | |
| UL35 | VP26 | capsid | Affects DNA packaging, mediates capsid assembly, trafficking post viral entry |
| UL39 | RR1 (ribonucleotide reductase) | accessory | Part of the ribonucleotide reductase (RR) complex, converts ribonucleotide diphosphates to corresponding deoxyribonucleotides, allowing for virus replication particularly in non-dividing cells |
| UL40 | RR2 (ribonucleotide reductase) | accessory | Part of the ribonucleotide reductase (RR) complex, converts ribonucleotide diphosphates to corresponding deoxyribonucleotides, allowing for virus replication particularly in non-dividing cells |
| UL41 | VHS | tegument | Viral RNase, degrades host transcripts and blocks antiviral responses |
| L43 | tegument | ||
| UL44 | gC | envelope | Mediates viral binding to heparan sulfate, regulates entry by a low-pH pathway |
| UL45 | envelope | Required for syncytia formation during HSV-1 gB syn infection | |
| UL46 | VP11/12 | tegument | Regulation of transcription, activates pathways for cell survival, blocks pathways for innate immunity activation |
| UL47 | VP13/14 | tegument | Regulation of transcription, modulating post-transcriptional processing of mRNAs |
| UL49 | VP22 | tegument | Facilitates viral gene expression, protein expression, and DNA replication; inhibits inflammasome |
| UL49.5 | gN | envelope | Binding partner of gM |
| UL50 | tegument | Nucleic acid metabolism | |
| UL51 | tegument | Participates in cytoplasmic envelopment; facilitates virus spread from cell-to-cell; recruits UL7 to tegument | |
| UL53 | gK | envelope | Participates in virion egress from host cell; regulates virus entry and fusogenic activity of the virion; complexes with UL20 |
| UL55 | tegument | Participates in cytoplasmic envelopment | |
| UL56 | tegument | Participates in cytoplasmic envelopment | |
| US1 | ICP22 | accessory | Regulates viral late gene expression; facilitates formation of complexes important for protein folding; participates in primary envelopment; blocks immune responses |
| US1.5 | accessory | Participates in viral gene transcription | |
| US2 | tegument | Protein trafficking | |
| US3 | Ser/thr protein kinase | tegument | Blocks apoptosis, enhances viral gene expression, facilitates capsid nuclear egress, phosphorylates numerous substrates |
| US3.5 | Ser/thr protein kinase | tegument | Phosphorylates substrates but cannot block apoptosis and does not facilitate nuclear egress |
| US4 | gG | envelope | Regulation of chemokines |
| US5 | gJ | envelope | Inhibits apoptosis and cell stress pathways |
| US7 | gI | envelope | Enhances virus spread from cell-to-cell; facilitates anterograde transport of virions after reactivation from latency; important for neurovirulence |
| US8 | gE | envelope | Enhances virus spread from cell-to-cell; facilitates anterograde transport of virions after reactivation from latency; important for neurovirulence |
| US8.5 | accessory | Localizes in the nucleoli | |
| US9 | tegument | Enhances virus spread from cell-to-cell; facilitates anterograde transport of virions after reactivation from latency; important for neurovirulence | |
| US10 | tegument | Important for neurovirulence | |
| US11 | tegument | Block PKR activation and shutoff of host translation; block IFN induction; regulation of virus genes expression; trafficking of unenveloped capsids | |
| US12 | ICP47 | accessory | Prevents MHC I antigen presentation, supports neurovirulence |