Sigmavirus (taxid:1308858)

Molecular biology



Enveloped, bullet shaped.



Negative-stranded RNA linear genome,about 12.6 kb in size. Encodes for 6 proteins.


The viral RNA dependent RNA polymerase binds the encapsidated genome at the leader region, then sequentially transcribes each genes by recognizing start and stop signals flanking viral genes. mRNAs are capped and polyadenylated by the L protein during synthesis.




  1. Attachement of the viral G glycoproteins to host receptors mediates Clathrin-mediated endocytosis of the virus into the host cell.
  2. Fusion of virus membrane with the vesicle membrane; ribonucleocapsid is released into the cytoplasm.
  3. Sequential transcription , viral mRNAs are capped and polyadenylated by polymerase stuttering in the cytoplasm.
  4. Replication presumably starts when enough nucleoprotein is present to encapsidate neo-synthetized antigenomes and genomes.
  5. The ribonucleocapsid binds to the matrix protein and buds via the host ESCRT complexes occurs at the plasma membrane, releasing new virions.

Matching UniProtKB/Swiss-Prot entries

(all links/actions below point to website)

6 entries grouped by strain

6 entries

Drosophila melanogaster sigma virus (isolate Drosophila/USA/AP30/2005) (DMelSV) reference strain

L_DMSVA RNA-directed RNA polymerase L (Protein L) (Large structural protein) (Replicase) (Transcriptase) ...
GLYCO_DMSVA Glycoprotein
NCAP_DMSVA Nucleoprotein (NP) (Nucleocapsid protein) (Protein N)
PP3_DMSVA Protein PP3
MATRX_DMSVA Matrix protein
PHOSP_DMSVA Phosphoprotein (P protein)