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Influenza C virus

Molecular biology


Enveloped. Usually rounded but can be filamentous. The virions are 80-120 nm in diameter.


segmented ssRNA(-) linear genome, encapsidated by nucleoprotein (NP) Contains 7 segments coding for 9 proteins. Segments size range from 0.9 to 2.3 kb. Genome total size is about 10 Kb


Viral RNA polymerase (PB1, PB2 and PA) transcribes one mRNA from each genome segment. Transcription is primed by cap snatching. mRNA are polyadenylated by the viral polymerase stuttering on a poly U track. NS mRNA can be alternatively spliced, giving rise to mRNA coding for NEP proteins. Polyprotein p42 is cleaved in M1 and CM2 proteins.



  1. Virus attaches to sialic acid receptor though HEF protein and is endocytosed by clathrins in the host cell.
  2. endosome acidification induces fusion of virus membrane with the vesicle membrane; encapsidated RNA segments migrate to the nucleus.
  3. Transcription of genomic segments by the viral polymerase produces mRNAs that are capped and polyadenylated by the viral polymerase.
  4. Replication of genomic segments.
  5. High level of M1 protein induces genomes segments export from nucleus by NEP protein.
  6. Virus assembly and budding occurs at the plasma membrane.

Host-virus interaction

Innate immune response inhibition

Influenza C virus inhibits the cascade leading to production of interferon-beta by targeting host RIG-I activation through NS1 protein.

Matching UniProtKB/Swiss-Prot entries

31 entries grouped by strain (browse by keywords)

All proteins are shown (view only 8 complete proteome entries)

8 entries

Influenza C virus (strain C/Ann Arbor/1/1950) reference strain

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HEMA_INCAAHemagglutinin-esterase-fusion glycoprotein (HEF) (EC
MAT_INCAAPolyprotein p42
NCAP_INCAANucleoprotein (Nucleocapsid protein) (Protein N)
NEP_INCAANuclear export protein (NEP) (Non-structural protein 2) (NS2)
NS1_INCAANon-structural protein 1 (NS1) (NS1C)
PA_INCAAPolymerase acidic protein (Polymerase 3) (RNA-directed RNA polymerase subunit ...
PB2_INCAAPolymerase basic protein 2 (RNA-directed RNA polymerase subunit P3)
RDRP_INCAARNA-directed RNA polymerase catalytic subunit (EC (Polymerase basic ...

5 entries

Influenza C virus (strain C/California/1978)

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HEMA_INCCAHemagglutinin-esterase-fusion glycoprotein (HEF) (EC
MAT_INCCAPolyprotein p42
NCAP_INCCANucleoprotein (Nucleocapsid protein) (Protein N)
NEP_INCCANuclear export protein (NEP) (Non-structural protein 2) (NS2)
NS1_INCCANon-structural protein 1 (NS1) (NS1C)

5 entries

Influenza C virus (strain C/Johannesburg/1/1966)

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HEMA_INCJHHemagglutinin-esterase-fusion glycoprotein (HEF) (EC
NCAP_INCJHNucleoprotein (Nucleocapsid protein) (Protein N)
PA_INCJHPolymerase acidic protein (Polymerase 3) (RNA-directed RNA polymerase subunit ...
PB2_INCJHPolymerase basic protein 2 (RNA-directed RNA polymerase subunit P3)
RDRP_INCJHRNA-directed RNA polymerase catalytic subunit (EC (Polymerase basic ...

4 entries

Influenza C virus (strain C/JJ/1950)

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MAT_INCJJPolyprotein p42
PA_INCJJPolymerase acidic protein (Polymerase 3) (RNA-directed RNA polymerase subunit ...
PB2_INCJJPolymerase basic protein 2 (RNA-directed RNA polymerase subunit P3)
RDRP_INCJJRNA-directed RNA polymerase catalytic subunit (EC (Polymerase basic ...

3 entries

Influenza C virus (strain C/Hyogo/1/1983)

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MAT_INCHYPolyprotein p42
NEP_INCHYNuclear export protein (NEP) (Non-structural protein 2) (NS2)
NS1_INCHYNon-structural protein 1 (NS1) (NS1C)

2 entries

Influenza C virus (strain C/Yamagata/1964)

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NEP_INCY6Nuclear export protein (NEP) (Non-structural protein 2) (NS2)
NS1_INCY6Non-structural protein 1 (NS1) (NS1C)

1 entry

Influenza C virus (strain C/Berlin/1/1985)

PB2_INCBEPolymerase basic protein 2 (RNA-directed RNA polymerase subunit P3)

1 entry

Influenza C virus (strain C/Nara/2/1985)

HEMA_INCNBHemagglutinin-esterase-fusion glycoprotein (HEF) (EC

1 entry

Influenza C virus (strain C/Taylor/1233/1947)

MAT_INCTAPolyprotein p42

1 entry

Influenza C virus (strain C/Yamagata/4/1988)

HEMA_INCYBHemagglutinin-esterase-fusion glycoprotein (HEF) (EC