Table 1.
Influenza A virus (IAV) gene products, expression mechanisms, and functions
| Segment | Segment length (nt) | Protein products | Expression mechanism | Length (aa) | Molecular weight (kDa) | Main function(s) |
|---|---|---|---|---|---|---|
| 1 | 2341 | PB2 | Canonical translation initiation | 759 | 85.7 | Component of the heterotrimeric viral RdRp; binds mRNA cap structures to promote cap snatching |
| PB2-S1 | mRNA splicing | 508 | 55 | Inhibitor of the RIG-I signaling pathway? | ||
| 2 | 2341 | PB1 | Canonical translation initiation | 757 | 86.6 | Component of the viral RdRp; nucleotide polymerase |
| PB1-N40 | Alternative AUG initiation (translation reinitiation) | 718 | 82.4 | Unknown; interacts with the viral polymerase | ||
| PB1-F2 | Alternative AUG initiation (leaky scanning) | 87 | 10.5 | IFN antagonist; pro-apoptotic activity | ||
| 3 | 2233 | PA | Canonical translation initiation | 716 | 84.2 | Component of the viral RdRp; viral mRNA endonuclease responsible for cap snatching |
| PA-X | Ribosomal frameshift | 252 | 29 | Exhibits endonuclease activity; contributes to host cell shutoff | ||
| PA-N155 | Alternative AUG initiation | 562 | 62 | Unknown | ||
| PA-N182 | Alternative AUG initiation | 535 | 60 | |||
| 4 | 1778 | HA | Canonical translation initiation | 566 | 61.5 | Homotrimeric surface glycoprotein; mediates receptor binding and virus entry |
| 5 | 1565 | NP | Canonical translation initiation | 498 | 56.1 | Encapsidation of vRNA (to form RNP complexes); required for transcription activity and vRNP nuclear import |
| eNP | Upstream AUG | 504 | 56.8 | Virulence factor for H1N1 IAVs | ||
| 6 | 1413 | NA | Canonical translation initiation | 454 | 50.1 | Homotetrameric surface glycoprotein; exhibits sialidase activity allowing release of virus progeny from the cell surface |
| NA43 | Alternative AUG initiation (leaky scanning?) | 440 | 48.6 | Uncertain, plasma-membrane-resident NA variant | ||
| 7 | 1027 | M1 | Canonical translation initiation | 252 | 27.8 | Matrix protein; known to interact with RNPs and viral membrane proteins; involved in RNP nuclear export, virus assembly, and budding |
| M2 | mRNA splicing | 97 | 11 | Acts as proton channel; required during virus entry (uncoating) and for membrane scission at the budding stages of infection | ||
| M42 | mRNA splicing and alternative AUG initiation | 99 | 13 | Variant of M2 with common functions | ||
| 8 | 890 | NS1 | Canonical translation initiation | 230 | 26.8 | Broad-spectrum IFN antagonist |
| NEP/NS2 | mRNA splicing | 121 | 14.2 | Involved in nuclear export of vRNPs | ||
| NS3 | mRNA splicing | 187 | 21 | Unknown | ||
| NSP | unknown | 167 | 18.1 | Unknown; protein expression bioinformatically proposed, but yet not experimentally detected | ||
| tNS1 | Alternative AUG initiation | 150/ 152 | 17 | Involved in inhibition of IRF3 |
Segment and protein sizes based on A/Puerto Rico/8/1934 (H1N1).
(RdRP) RNA-dependent PNA polymerase, (mRNA) messenger RNA, (IFN) interferon, (vRNA) virion RNA, (IAV) influenza A virus, (RNP) ribonucleoprotein.