HIV and AIDS

• HIV compromises the immune system and can lead to AIDS - this makes them more vulnerable to other infections
• HIV infects helper T cells which act as a host cell. These helper T cells would've sent chemical signals that activates phagocytes, cytotoxic cells and B-cells so they are hugely important in the immune response
• people infected with HIV develop AIDS when helper T cell numbers in their body reach a critically low level
• Initial infection:

  1. HIV rapidly replicates + server flu-like symptoms
  2. latency period + no symptoms BUT STILL REPLICATIONS
• HIV is a virus that infects and eventually kills helper T cells - without helper T cells the immune system cannot stimulate B cells to produce antibodies

  1. B plasma cells can’t secrete antibodies for agglutination and destruction of pathogens by phagocytosis
  2. Immune system deteriorates
  3. As a result, the body is unable to produce an adequate immune response and becomes susceptible to other infections and cancers.
  4. It is these secondary diseases that ultimately cause death. HIV does not kill individuals directly
• people infected with HIV develop aids when helper T cell numbers in their body reach a critically low level
• as AIDS progresses number of t cells decrease so patients become susceptible to more serious infections like tuberculosis or toxoplasmosis (parasite infection of the brain)

  • THESE SERIOUS INFECTIONS THAT KILL AIDS PATIENTS NOT HIV ITSELF
• HIV structure:

  • nucleic acid containing RNA
  • reverse transcriptase needed for viral replication
  • capsid a protein coat
  • attachment proteins are crucial for the virus to enter host cells attaching to receptors

  A) attachment proteins

  B) RNA

  C) reverse transcriptase

  D) capsid

  E) envelope

  
• HIV REPLICATION:

  1. the attachment proteins attaches to the receptors on cell surface membrane of host helper t cells
  2. the capsid is released into the cell releasing the RNA into the cells cytoplasm
  3. inside the cell reverse transcriptase is used to make a complementary strand of DNA from RNA template
  4. double stranded DNA made and inserted into the human DNA
  5. Host cells enzymes are used to make viral proteins from viral dna
  6. viral proteins are assembled into new viruses which infect other cells
• Explain why viruses are described as acellular and non-living

  1. Acellular cause has no cell surface membrane
  2. Non-living cause have no metabolic reactions