1. Phagocyte

2. B cells Receptor B Cell Naïve B cell

3. B cells and antibodies daughter cells produce antibodies phagocyte consumes an antibody coated virus Antibodies neutralise antibodies B cell attaches to antigen cloning of daughter cells

4. Cytotoxic CD8 cells CD8 cells can recognise markers on the outside of infected cells CD8 destroys infected cell which stops cell from producing more virus or bacteria

5. Antigen presenting cells These cells can engulf invading organisms The foreign organism is broken up into smaller pieces Antigens presented to CD4 cells

6. CD4 cell

7. Analogy for the immune system

8. Naïve and Memory B cells Naïve B cell  Once activated it divides many times making two types of clones  The plasma cell which makes and releases large amounts of the appropriate antibody  The memory B cell which can live for years Memory B cells  The existence of memory B cells means that the body can respond much more quickly

9. CD4 and CD8 Cluster of Differentiation  Molecules on the surface of the cells that help the T cell attach to the antigen CD4 cells  Th1 (humoral response) Th2 (cell mediated response) Th0 (??) CD8 cells  Cytotoxic lymphocytes (CTL) CD45RA – Naïve cells CD45RO – Memory cells

10. CD4 count viral load over time Viral LoadCD4 Count Set Point Levels in the Blood Below the limit of the test SeroconversionAsymptomaticSymptomatic

11. HIV virion Reverse transcriptase enzyme Protein p24 Protein p18 Fatty (lipid bilayer) membrane Glycoprotein gp120

12. Vaccine - Ideal characteristics Prevent transmission by mucosa & injecting Excellent safety profile Single dose administration Offers protection for a long time Low cost Stability and ease of administration Works against a wide range of different strains

13. Immune system responses Humoral response  Based on antibodies and the B cells that produce them Cell-mediated response  Based on cytotoxic CD8 cells Mucosal immunity  The above but concentrated in the mucosal membranes where most transmission occurs Current trend  is to aim to stimulate a sufficient HIV-specific CTL response to control or prevent HIV infection

14. Types of vaccine Live attenuated vaccines  Defective or weakened form of the virus  Previous example original smallpox vaccine, vaccinia  Research in monkeys indicates may slowly lead to immune disease Inactivated or 'killed' vaccines Recombinant sub-unit envelope vaccines Recombinant vectored vaccines DNA vaccines and replicons Combination vaccines or ‘prime and boost’

15. Types of vaccine Live attenuated vaccines Inactivated or 'killed' vaccines  Second classic technique (e.g. Dr Jonas Salk in creating the world's first successful polio vaccine)  No-one has yet claimed any significant success  Maybe difficult to distinguish between vaccine immune response and infection Recombinant sub-unit envelope vaccines Recombinant vectored vaccines DNA vaccines and replicons Combination vaccines or ‘prime and boost’

16. Types of vaccine Live attenuated vaccines Inactivated or 'killed' vaccines Recombinant sub-unit envelope vaccines  Seek to stimulate antibodies to HIV by mimicking proteins on the surface of HIV (e.g. gp120)  Initial research was strain-specific and produced poor antibody responses  Recently more hope Recombinant vectored vaccines DNA vaccines and replicons Combination vaccines or ‘prime and boost’

17. Types of vaccine Live attenuated vaccines Inactivated or 'killed' vaccines Recombinant sub-unit envelope vaccines Recombinant vectored vaccines  incorporate harmless bits of HIV into established vaccines ALVAC series of vaccines are canarypox based vaccines Vaccine strains of adenovirus recombinant rabies virus vaccines DNA vaccines and replicons Combination vaccines or ‘prime and boost’

18. Types of vaccine Live attenuated vaccines Inactivated or 'killed' vaccines Recombinant sub-unit envelope vaccines Recombinant vectored vaccines DNA vaccines and replicons  involve HIV genetic sequences which, once injected, induce expression of HIV antigens by human cells.  In the case of replicons, these sequences are wrapped in the outer coat of an unrelated virus. Combination vaccines or ‘prime and boost’