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Synthetic Biology in Vaccine Development

Explore the historical overview and genetic methods in vaccine development, with a focus on influenza as a case study. Learn about traditional vaccine approaches and the next generation of vaccines using genetic techniques.

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Synthetic Biology in Vaccine Development

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  1. Synthetic Biology in Vaccine Development Julius Ho Biol1220 4/20/10

  2. Outline • Historical overview of vaccines • Genetic methods in vaccine development • Use influenza as an example for new synthetic bio approaches

  3. Traditional vaccines • Use of inactive or weakened compounds from the microorganism causing disease • Different approaches • Heterologous • Attenuated • Inactivated • Toxoid

  4. Heterologous • Immune response from a non-pathogenic relative of the organism • Smallpox vaccine (1796): • Edward Jenner uses coxpox virus to induce resistance to smallpox http://en.wikipedia.org/wiki/File:Edward_Jenner2.jpg http://emergency.cdc.gov/agent/smallpox/images/hand_position_for_vaccination.jpg

  5. Attenuated • Reduce pathogenicity of virus/bacteria by repeated culturing • TB vaccine (1921): • Discovery of Mycobacterium bovis, a relative of M. tuberculosis • Selection of less-virulent strains over 10+ years http://www.bbc.co.uk/jersey/content/images/2005/11/24/jersey_cow_350x350.jpg http://feww.files.wordpress.com/2008/10/tb.jpg

  6. Inactivated • Kill the actual pathogen but expose immune system to the remnants • Polio vaccine (1952): • Polio virus grown in animal cell line, then inactivated by formalin http://americanthings.files.wordpress.com/2009/10/meisenproductionsdotcom.jpg http://en.wikipedia.org/wiki/File:Polio.jpg

  7. Toxoid • Neutralize the toxin produced by pathogens and inject into patient • Tetanus vaccine (1924): • Culturing Clostridium tetani, collecting tetanospasmin toxin and inactivating with formalin http://en.wikipedia.org/wiki/File:CBell1809.jpg http://www.livestockpros.com/images/catttlevacs/87-20.jpg

  8. Next generation of vaccines • A genetic approach: • Determining the immunogenic portion of a microorganism • Producing subunits without the harmful or replicative portions of pathogen • Examples: • Hepatitis B vaccine: surface antigen used to be isolated in human blood, transplanted into yeast in 1980s • HPV vaccine: surface antigens produced in yeast, approved 2006 http://en.wikipedia.org/wiki/File:Hepatitis_B_virus_v2.png http://en.wikipedia.org/wiki/File:Gardasil_vaccine_and_box_new.jpg

  9. Influenza: A Case Study • Traditional methods: • Inactivated: Inject eggs with virus, incubate and allow virus to proliferate, apply formalin to “kill” • Attenuated: Expose virus to repeated cold adaption cycles, until it no longer can reproduce in body temp (directed evolution!) http://science.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Science/Images/Content/cultivating-flu-vaccine-sf5473-lw.jpg http://beta.thehindu.com/multimedia/dynamic/00001/SWINE_FLU_VACCINE_1_1628f.jpg

  10. Current shortcomings • Takes around six months to prepare annual vaccine • Only a prediction of the expected strains • Variable quality of egg product • Contamination • Difficult to control amount of virus • Live-attenuated vaccine is unsuitable in immunocompromised patients

  11. Synthetic biology solutions • Virus-like particles • DNA vaccine • Synthetic attenuation

  12. Virus-Like Particles • Quan et al. 2010, “Virus-Like Particle Vaccine Protects against 2009 H1N1 Pandemic Influenza Virus in Mice” • The HA and M1 genes were converted to cDNA, PCR amplification, insertion into pFastBac vector • Plasmids placed into a baculovirus, infected into insect cells • Structural proteins aggregate and form empty capsules in supernatant Western blot to confirm HA and M1 in VLP Electron micrograph of VLP

  13. Quan et al. 2010 continued • Mice injected with isolated VLPs

  14. The future: • A universal flu vaccine • Adar et al. 2009, “A universal epitope-based influenza vaccine and its efficacy against H5N1” • Insert a variety of flu epitopes on flagellin chassis • Flagellin detectable by TLR5 in innate immune system

  15. DNA vaccine • Inserting plasmid DNA for immunogenic portions directly into human cells; producing antigens on-site • Advantages: • Easy to synthesize and adapt • Stable storage • Prolonged exposure to immunogen • Most similar expression/structure to actual infection http://www.niaid.nih.gov/news/newsreleases/2005/pages/wnvvaxtrial.aspx

  16. DNA vaccine to H1N1 • R.J. Drape et al. 2006, “Epidermal DNA vaccine for influenza is immunogenic in humans” • HA coding sequence isolated by RT-PCR, inserted into DNA plasmid • DNA coated on 1-3um gold particles, delivered by gene gun

  17. Synthesis of attenuated viruses • Problem: Attenuated virus reverting to wild type • Directed mutations • Macadam et al. 2006, “Rational Design of Genetically Stable, Live-Attenuated Poliovirus Vaccines of All Three Serotypes: Relevance to Poliomyelitis Eradication” • Altering thermodynamic stability of virus domain with point mutations (using splicing segments with RE)

  18. Synthetic attenuation cont. • Using knowledge of codon pair bias • Coleman et al. 2008, “Virus Attenuation by Genome-Scale Changes in Codon Pair Bias” • Preserving AA sequence of P1 structural domain (2643bp), but modifying synonymous codons (500-600 mutations) • Changes in translation

  19. Sources • http://discovermagazine.com/2009/jul-aug/27-vaccine-production-horribly-outdated-3-ways-fix-it • http://www.i-sis.org.uk/LASIVCSQ.php • http://www.who.int/vaccines/en/hepatitisa.shtml • http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2820088/ • http://www.who.int/biologicals/areas/vaccines/dna/en/index.html • http://www.cdc.gov/mmwr/preview/mmwrhtml/00041645.htm

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