1VaccinesRobert BeattyMCB150Passive vs ActiveImmunityPassive immunizationtransfer of antibodiesVaccines are activeimmunizations(mimic natural infections)Passive ImmunizationLasts as long as antibodies are present. Does not establish memory. e.g. gammaglobulin shots (pooled human IgG). How do vaccines work?Vaccines are active immunization to provideprotection from disease by establishing memoryT and B cells.Some vaccines prevent disease but not infection.2Preventive vs Therapeutic vaccinesPreventive Most vaccines in use now provide protectionfrom primary infection or prevent disease.Therapeutic vaccinesGiven to infected people to prevent disease,reduce effects of chronic infection, or stimulateanti-tumor response.Smallpox---Vaccine SuccessReasons for the smallpox success storyNo animal reservoir.Lifelong immunity.One serotype (no antigenic variation).Effective attenuated vaccine.Successful eradication of smallpox last known case in world in 1977. Smallpox vaccine is Vaccinia virus.Issues for Vaccine Design Establishing Protective ImmunityWhich antigens are immunodominant?What type of immune response providesprotection from disease?How to elicit long-term immune protection?Issues for Vaccine DesignHow to establish protective immunity?Which antigens at what stage in life cycle do you vaccinate with?What type of immune response protects? MalariaRbc stagePre-liver stage3Issues for Vaccine DesignPrevent potential pathogenesisDisease often a result of a immune response.Some vaccine trials actually resulted in worsedisease.Vaccines must avoid immune pathology.Issues for Vaccine DesignRoute of immunizationImmunization site will influence whereimmune responses are elicited.Important to know route of infection inorder to elicit protective immunity.Primary vaccine routes – Intramuscular (IM)– Intravenous (IV)– OralIssues for Vaccine DesignRoutes of immunizationIntranasal live vaccine for influenza was designed so that it will replicate only in nasalpassagesRoutes for vaccination may include skin,subcutaneous, or intranasal."Flu-mist"Issues for Vaccine DesignAdjuvantsAdded to non-replicating vaccines in order toenhance immunogenicity.(Bind TLRS, provide inflammatory response, and activate APCs)Inorganic salts are routinely used in humans.• Aluminum hydroxide• Aluminum phosphate• Calcium phosphateNew lipid adjuvants• Liposomes• Immune stimulating complexes (ISCOMs)4Other ways to enhanceimmunogenicityInject vaccine with other pathogen to provideadjuvant-like effectE.g. Bordetella pertussis (whooping cough) is given withtetanus toxoid and diptheria toxoid.Inject cytokines with vaccineE.g. GM-CSF injected with vaccine or inserted in plasmid.Issues for Vaccine DesignAntigenic VariationViruses have different antigenic subtypes andhigh mutation rates.– Example: Antigenic drift of influenza usuallymeans a new vaccine formulation each year.NOTE**any potential HIV vaccine will have to deal withdifferent serotypes and high mutation rate.Types of Vaccines Attenuated vaccinesaka "Live Vaccines"Attenuated vaccines are made by growingpathogen in non-human cell culture.Less virulent in humans.– Examples Sabin Oral polio vaccine (OPV).Measles. Mumps. Rubella. Varicella zoster virus(VZV).Types of Vaccines Attenuated vaccinesPathogen is passaged in non-human cell culture until it has low replication in human cells.5Types of Vaccines Attenuated vaccinesAdvantages: – Self-replicating– Authentic antigen presentation– More effective at eliciting CTLsDisadvantages:– Reversal of virulence– One lab-adapted strain does not deal with strainvariability Types of Vaccines Inactivated VaccinesWhole, killed, non-replicating organismInactivated by heat, chemicals, or irradiation– Examples Influenza. Hepatitis A virus, Pertussis,Salk inactivated polio vaccine (IPV)Types of Vaccines Inactivated VaccinesAdvantages:– No virulence– All antigens presentDisadvantages:– No replication of pathogen– Poor antigen presentation for CMITypes of Vaccines Inactivated Flu VaccineTraditional approach: Cell culture– Identify target "new virulent" strains– Grow in eggs with "harmless" flu strain– Genetic reassortment--expand and inactivateNew approaches:Reverse genetics = clone in virulent H or NRecombinant H grown in insect cells6Flu Vaccine Issues in USStandard Inactivated vaccine.– Usually 100 million doses available each year. Flu-mist– Live vaccine and only 1-2 million doses.Recombinant vaccine still in clinical trials.Many H5N1 vaccines in the works.Why have attenuated vaccinesbeen so successful?Advantages of replicating live vaccines:– low cost, single dose, no adjuvant, generates IgG,IgA, and cell mediated immunity.Big disadvantage is potential for revirulence.Attenuated (self-replicating/ live)vs Inactivated (non-replicating/ killed)Success of Polio VaccinationAttenuated Oral Polio Vaccine (OPV) Sabin 1954 Inactivated Polio Vaccine (IPV) Salk 1957(Sabin OPV can have reversal of virulence causing paralytic disease 1:4 million)7Types of VaccinesRecombinant proteins/synthetic peptidesIdentify immunogenic proteins.– Usually envelope or outer membrane proteins.Produce large quantities for immunization.– Adjuvant to get immune system to notice proteins.– Examples: Hepatitis B virus.Potential HIV vaccines.Types of VaccinesRecombinant proteins/synthetic peptidesAdvantages:– Potentially less expensive production– No reversionDisadvantages:– No replication of pathogen, need adjuvant – Poor for CMI– Short lived immunity?Human Papilloma virus (HPV) vaccine(causes warts and cervical cancer)Vaccinia with HPV capsid proteins used inculture to make "virus-like particles" (no HPVviral DNA).Vaccine isempty viral capsids + alum. Subunits in live vectorsInsert genes from pathogen into a well characterized vaccine vector. (Bacterial or viral vectors: e.g. Vaccinia, Adenovirus,Salmonella, BCG).8Types of VaccinesSubunits in live vectorsAdvantages:– Self replicating vectors.– Vector acts as adjuvant.– Good for CTLs.Disadvantages:– Infecting with other virus or bacterium.– May be less efficient for antibodies.Types of VaccinesHIV Canarypox vaccineInsert HIV genes into canarypox genome.Canarypox is non-human pathogen but canreplicate thus vaccine