HIV

• Matrix is a layer of proteins situated under the outer envelope
• Attachment proteins are used by the virus to identify and attach to host cells
• Capsids are a protein layer that encloses two strands of RNA and some enzymes
• RNA contains the genetic material needed to reproduce
• Lipid envelope is not present in all viruses
• Reverse transcriptase is an enzyme that catalyses the production of DNA from RNA
• HIV enters the bloodstream and circulates around the body
• HIV binds to the cell surface membrane protein most frequently found on T helper cells
• Protein capsid fuses with cell surface membrane, RNA and reverse transcriptase enter cell
• Reverse transcriptase catalyses synthesis of DNA from viral RNA
• Viral DNA diffuses through a nuclear pore into the nucleus where it is inserted into the cell's own DNA, remains inactive for a long time
• When the viral DNA becomes active, it produces mRNA using cell enzymes. This contains genetic information for making new viral proteins and RNA to go into new HIV particles
• mRNA diffuses out the cell nucleus through a nuclear pore
• Newly made viral proteins are assembled into new virus particles inside the cytoplasm
• mRNA code provides instructions for cell's protein synthesis mechanisms to manufacture HIV particles
• HIV particles break away from T helper cells with a piece of cell surface membrane, forming the lipid envelope