Infectious Salmon Anemia Virus

A small project about ISAVirus brought to you by a group of Year 2 MBIO students from Ngee Ann Polytechnic.

Click on the pastel orange box on the left for the names of the students involved in this project.

Thank you.

:)

Life Cycle of ISAV
Thursday, 26 January 2012 @ 12:49
  1. The virus enters the host cell(salmon) by binding its hemagglutinin to the sialic acid found on glycolipids or glycoproteins on the surface of the host cell.
  2. The host cell then endocytoses the virus.
  3. Due to the low pH environment in the endosome, the virus mutates and fuses its small projections(envelope) with the endosomal membrane.
  4. A signal is received by the endosome to release the viral nucleoclaspid into the cytoplasm of the host cell.
  5. The viral nucleoclaspid will then proceed to the nucleus of the host cell where the replication occurs.
  6. In the nucleus of the host cell, the viral nucleoclaspid will go through transcription to prepare itself with necessary proteins needed for replication.
  7. The primary transcription involves “cap-snatching”.
  8. The viral endonuclease(PB2)  “steals” the 5’methyguanosine cap  and around 10 to 13 nucleotides from the host cell mRNA.
  9. This is used as the primer for the transcription of the PB1 protein(viral transcriptase).
  10. The different types of proteins produced that are necessary for its life cycle can be found in the Key Protein segment(e.g Hemagglutinin, neuraminidase)
  11. Once the initial proteins for the virus are produced, the RNA strands will then be produced. Since ISAV is more similar to the Influenza C virus, it produces 7 complementary positive sense RNA strands from 8 complementary negative sense RNA segments.
  12. These positive sense RNA or cRNA strands lack of 5’capped primer and the 3’poly A tail found in the mRNA(The strands were incomplete). Once the strands are completed, it becomes negative sense RNA strands.
  13. A variety of proteins will then help the negative sense RNA strands to exit the nucleus and finally into the cytoplasm.
  14. Hemagglutinin and neuraminidase(key proteins) have already gone through glycosylation, polymerization, acylation. These proteins, as well as matrix protein 2(M2) will travel together heading towards the plasma membrane.
  15. Together, these proteins, the eight negative mRNA strands plus a matrix protein 1(M1) will start the budding process at the plasma membrane of the host cell.
  16. Once the virus buds, the neuraminidase destroys the sialic acid receptors on the plasma membrane and the virus leaves the host cell, which will eventually die.