Finding a Cure Which HIV vaccine would you choose

Finding a Cure: Which HIV vaccine would you choose? Ramil Sapinoro Life Sciences Learning Center University of Rochester Medical Center AIDSVax Inc. Department of Vaccine Research 1979 Cure Drive Rochester, NY 14620 Dear Research Technician, We are excited to collaborate with your organization in developing a AIDS vaccine. I am sending you 4 possible DNA vaccines that you could use in your vaccine trials. I‟m not sure which combinations of the three HIV genes are in each one. You will have to check this. Along with the DNA, I have included some data collected from preliminary animal studies. We injected animals with each of the three HIV genes alone: the gag gene codes for HIV structural proteins; the env gene codes for the virus envelope proteins; and the pol gene codes for viral enzymes. We used mice as an experimental animal. Sincerely, Clarke Kent, Ph.D Director Center for Vaccine Research University of Rochester How does the Immune System fight invaders? Antigen MHC APC Virus Antigen Presenting Cells (ex: macrophages) Capture invaders (pathogens), destroy them, and display parts of them (antigens) on proteins called MHC’s How does the Immune System fight invaders? Helper T Cells See antigens presented by APC‟s and does two things: 1) Turn on Cytotoxic T Cell – these T Cells can go on to kill other cells that present the antigen (infected cells as well as macrophages) 2) Activate B Cells T APC How does the Immune System fight invaders? T T Cytotoxic T Cell B APC B Cell How does the Immune System fight invaders? Helper T cell produces signaling proteins that tell B Cells that have antibodies against the antigen to make more B Cells and free floating antibodies T Cytotoxic T cell produces signaling proteins that tell infected cells to kill themselves B Infected Cell B BB How do vaccines „help‟ the immune system to fight off viruses? What would a Successful Vaccine Do? •Stimulate the production of antibodies •Stimulate the production of Cytotoxic T Cells BB •Remember the pathogen (Memory cells) •Not cause disease Vaccine Approaches What parts of a pathogen could we use to stimulate the immune response and not cause disease? Live-attenuated Virus Inactivated Virus DNA Protein subunit Synthetic peptide Vaccines Currently Available Disease/Virus Polio Influenza Measles/Mumps/Rubella Type of Vaccine Inactivated virus Inactivated virus Live-attenuated Live-attenuated Live vaccinia virus Recombinant protein Virus-like particles Chicken Pox Smallpox Hepatitis B Cervical Cancer What is HIV? HIV = Human Immunodeficiency Virus •Small •Replicates within cells of living hosts •Composed of RNA •Pathogenic: Has the ability to cause disease (AIDS) T HIV causes disease because it kills helper T cells APC HIV Genome and Structure The HIV genome has three main genes… gag gene pol gene env gene env proteins Viral envelope proteins gag proteins Capsid Matrix pol proteins Viral enzymes Four Potential Vaccines V1 V2 V3 V4 gag gene pol gene env gene pol gene env gene gag gene gag gene pol gene Which of these possible pieces of DNA are in each vaccine? How will you find out? env gene pol gene Which genes are in the vaccines? Cut with Restriction Enzyme V1 DNA Vaccine ? ? ? ? V2 DNA Vaccine V3 DNA Vaccine V4 DNA Vaccine Gel electrophoresis of digested vaccines You have been given vaccines that have been pre-digested with restriction enzyme. You‟ll need to run the DNA fragments out on a gel to see what genes are in each vaccine. V1 V2 V3 V4 Loading your gel Loading your gel Gel electrophoresis of digested vaccines V1 V2 V3 V4 • Load the gel • Carry the gel to a power source • Fill the gelbox with TAE buffer (fill the box so that the top of the gel is just covered) • Put the lid on the gel • Run the gel for about 10 minutes at 120 volts Which genes are in the vaccines? gag gene pol gene env gene Restriction Enzyme gag gene Well pol gene env gene Gel electrophoresis Which genes are in the vaccines? gag gene pol gene Restriction Enzyme gag gene Well pol gene Gel electrophoresis Which genes are in the vaccines? pol gene env gene Restriction Enzyme Well pol gene env gene Gel electrophoresis Which genes are in the vaccines? gag gene Restriction Enzyme gag gene Well Gel electrophoresis Which genes are in the vaccines? pol gene Restriction Enzyme Well pol gene Gel electrophoresis Which genes are in the vaccines? env gene Restriction Enzyme Well env gene Gel electrophoresis Which one of these would you use in a human trial? gag gene pol gene env gene pol gene env gene gag gene pol gene gag gene env gene pol gene Which ones do you KNOW you would NOT want to use? Of the others, how will you decide which ones to use in human trials? Vaccine study in an animal model BB Amount of Antibodies DNA injected into mice Which one(s) would you use to make a vaccine? Vaccine study in an animal model BB Amount of cytotoxic T-cell Activity DNA injected into mice Which one(s) would you use to make a vaccine? More about HIV/AIDS… CD4 Helper T Cell HIV Lifecycle Global HIV infections, Worldwide HIV -1 infections, Dec. 2002 Dec 2006 http//www .unaids.or g/hivaidsinfo/documents.html E. Eur/Cen Asia 1.2 million Subtypes: B & ? Sth, SE Asia 6.0 million Subtypes: C, E, B E. Asia, Pacific 1.2 million Subtypes: C & ? Global Total (appr ox) Total: 42 million W. Eur ope 0.6 million Subtypes: B N. America 1.0 million Subtypes: B Africa 30.0 million Subtypes: C, A, D, E, B Latin America, Caribbean 1.9 million Subtypes: B, C Omitted subtypes F-J (rare); groups N, O HIV Treatment: Anti-virals Reverse Transcription Inhibitors Protease Blockers X What is in the vaccines? Which ones would you use in human trials? Which genes are in each of the four potential vaccines? Which of the potential vaccines would you NOT use? V1 V2 V3 V4 What other information might you need to make a decision on which one to use? Clinical Trials: Testing in Humans Phase Objective Safety and dose Additional safety and immunogenicity Number of Volunteers I 20–50 / trial II 100’s / trial III Efficacy and protection 1000’s / trial Phase Objective Safety and dose Additional safety and immunogenicity Number of Volunteers I 20–50 / trial II 100’s / trial V2 and V4 III Efficacy and protection 1000’s / trial You will be testing the serum of a group of people who have either been injected with V2, V4 or a placebo to see if they respond to the vaccine by making antibodies against the appropriate proteins V2 Each volunteer is injected with one vaccine. After a time, serum is collected from the volunteer, and analyzed for the presence of antibodies using an ELISA assay… Serum Obtain three absorbent squares and label “G” (gag) “P” (pol) and “E” (env)… Spot the gag, pol and env proteins on their appropriate spots… Gag Pol Env Place serum on each of the squares – the serum contains antibodies… Gag Pol Env If the volunteer has antibodies against the HIV proteins, those antibodies will bind to the proteins on the paper. Excess antibodies will wash off… Gag Pol Env Add labeled “Secondary Antibody” This secondary antibody binds to all human antibodies, and has a colored tag… Gag Pol Env Upon the addition of “developing solution,” the colored tag will become visible… Gag Pol Env You will each be given one serum sample from one volunteer – follow the instructions in your handout to determine if the volunteer made the appropriate antibodies… Which vaccine worked the best in the trial? Vaccine Given Volunteer # Gag Pol Env Why do we need to test immunogenicity? Diversity, diversity, diversity… People have different MHC alleles Person 1 Immune response Antigen MHC allele #1 MHC allele #2 Person 2 No immune response APC APC MHC Polymorphism Challenges in HIV Vaccine Research • Viral Genetic Diversity: HIV is not just one specific virus. Immune Protection: Scientists don‟t know what immune responses are needed, or how strong they need to be. • • Neutralizing Antibody: Difficult to generate broadly neutralizing antibodies. Vaccine Testing: Slow process, very expensive • …but on the Brightside… • Precedent from other systems: Success against other viral infections • Precedent from animal studies: Long-term control of infection in vaccinated monkeys • Immune control of HIV-1: Infected individuals control infection • Vaccine Trials: In progress