BRAINCAKERetrovirus Replication
Retroviruses such as HIV replicate by copying their RNA genome into DNA and inserting it into the host's DNA. Using HIV as the example:
1. Attachment: the glycoprotein gp120 on the envelope binds to CD4 receptors on T helper cells (with a co-receptor).
2. Entry: the envelope fuses with the host cell membrane and the capsid enters the cytoplasm, where the RNA and enzymes are released.
3. Reverse transcription: reverse transcriptase uses the viral RNA as a template to make a single strand of complementary DNA (cDNA). It then makes a second DNA strand, giving double-stranded DNA.
4. Integration: the dsDNA enters the nucleus and integrase inserts it into a host chromosome. The inserted viral DNA is called a provirus.
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Key terms in this lesson
- integrase
- A retroviral enzyme that inserts viral DNA into a chromosome of the host cell, forming a provirus.
- reverse transcriptase
- A viral enzyme that synthesises DNA from an RNA template, used by retroviruses such as HIV.
More in Prokaryotic Cells
- DNA Virus Lytic Pathway
- RNA Virus Replication
- Positive ssRNA Viruses
- Negative ssRNA Viruses
- Viruses and Disease
- The Spread of Viral Diseases
- Treating Viral Diseases
- Preventing Viral Diseases
All 31 lessons in Prokaryotic Cells · All Edexcel AS-level Biology topics