(Prepared by: Srushti Bhoite - 20220901003)
WHAT IS A RETROVIRUS?
A retrovirus is a virus that uses RNA as its genetic material. Upon infection with retrovirus a cell converts RNA into DNA which is inserted into host cell. The cell then produces more retroviruses which infect other cells.
HISTORY AND IMPORTANCE
Fifteen years ago retroviruses were studied to use animal models for studying human cancer. The historical importance of retroviruses in discovery of cancer genes is widely appreciated. The central goals of retrovirology are treatment and prevention of AIDS and use of retroviruses as gene delivery devices.
REPLICATION PROCESS
Let’s consider example of HIV to understand replication of retroviruses:
1] Attachment- virus binds to receptor on the host cell surface. In HIV this receptor is found on surface of immune cells called CD4 T cells.
2] Entry - envelope surrounding HIV fuses with membrane of host cell which allows the virus to enter host cell.
3] Reverse transcription – It uses reverse transcriptase enzyme to convert RNA genetic material into DNA.
4] Genome integration - the viral DNA travels through nucleus, the viral enzyme integrase is used to insert viral DNA into host cell’s DNA.
5] Replication - once DNA is inserted into host cell’s genome it uses host cell’s machinery to produce new viral components like viral RNA and proteins.
6] Assembly - the viral components combine close to cell surface and begin to form new HIV particles.
7] Release – new HIV particles push out from host cell surface and forms another mature HIV particle with the help of viral enzyme protease. Once outside the cell these particles can infect other CD4 T cells. [1]
References
[1] G. Rozera et al., “Analysis of HIV quasispecies and virological outcome of an HIV D+/R+ kidney–liver transplantation,” Virol J, vol. 19, no. 1, Dec. 2022, doi: 10.1186/s12985-021-01730-w.
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