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Phlebovirus

Molecular biology

VIRION

Enveloped, spherical. Diameter from 80 to 120nm. Glycoproteins at the surface of the envelope are arranged on an icosahedral lattice, with T=12 symmetry.

GENOME

Segmented Negative-stranded RNA linear genome, L segment is about 6.4kb, M segment about 3.2kb and S segment about 1.7kb.
Encodes for six proteins.

GENE EXPRESSION

Transcription starts by viral RNA dependent RNA polymerase (L) binding to a promoter on each encapsidated segment, and is terminated by a strong hairpin sequence at the end of each gene. mRNAs are capped by L protein during synthesis, but are not polyadenylated.
S segment uses ambisense strategy to encode for several proteins: both genomic and antigenomic RNA are transcribed. The hairpin sequence is a stop polymerase signal which prevents ambisense transcription from producing dsRNA. M segment encodes for a polyprotein which is cleaved by host protease into Gn and Gc proteins.

REPLICATION

CYTOPLASMIC

  1. Virus attaches to host receptors though Gn-Gc glycoprotein dimer, and is endocytosed into vesicles in the host cell.
  2. Fusion of virus membrane with the vesicle membrane; ribonucleocapsid segments are released in the cytoplasm.
  3. Transcription, viral mRNAs are capped in the cytoplasm.
  4. Replication presumably starts when enough nucleoprotein is present to encapsidate neo-synthetized antigenomes and genomes.
  5. The ribonucleocapsids migrate under the plasma membrane and buds, releasing the virion.

Host-virus interaction

Inhibition of host transcription initiation

The Rift valley fever virus NSs protein instead plays a role in the inhibition of the host transcription initiation by acting on host TFIIH.

Matching UniProtKB/Swiss-Prot entries

17 entries grouped by strain (browse by keywords)

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

4 entries

Rift valley fever virus (strain ZH-548 M12) (RVFV) reference strain

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GP_RVFVZEnvelope glycoprotein (GP) (M polyprotein)
L_RVFVZRNA-directed RNA polymerase L (Protein L) (EC 2.7.7.48) (Large structural ...
NCAP_RVFVZNucleoprotein (Nucleocapsid protein) (Protein N)
NSS_RVFVZNon-structural protein NS-S

4 entries

Uukuniemi virus (strain S23) (Uuk) reference strain

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GP_UUKSEnvelope glycoprotein (GP) (M polyprotein)
L_UUKSRNA-directed RNA polymerase L (Protein L) (EC 2.7.7.48) (Large structural ...
NCAP_UUKSNucleoprotein (Nucleocapsid protein) (Protein N)
NSS_UUKSNon-structural protein NS-S

3 entries

Punta toro phlebovirus

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GP_PTPVEnvelope glycoprotein (GP) (M polyprotein)
NCAP_PTPVNucleoprotein (Nucleocapsid protein) (Protein N)
NSS_PTPVNon-structural protein NS-S

3 entries

Toscana virus (Tos)

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L_TOSVRNA-directed RNA polymerase L (Protein L) (EC 2.7.7.48) (Large structural ...
NCAP_TOSVNucleoprotein (Nucleocapsid protein) (Protein N)
NSS_TOSVNon-structural protein NS-S

2 entries

Sandfly fever sicilian virus (SFS)

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NCAP_SFSVNucleoprotein (Nucleocapsid protein) (Protein N)
NSS_SFSVNon-structural protein NS-S

1 entry

Rift valley fever virus (RVFV)


GP_RVFVEnvelope glycoprotein (GP) (M polyprotein)