Chapter 7-Vaccines Vaccination Current and future vaccines Subunit vaccines Peptide vaccines Genetic immunization: DNA vaccines Attenuated vaccines Vector vaccines Monoclonal antibody passive immunity

Edward Jenner used the cowpox virus to vaccinate individuals against smallpox virus in 1796 See http://www.youtube.com/watch?v=jJwGNPRmyTI Smallpox

Table 7.1

Table 7.2 The “big three” infectious diseases globally: HIV, malaria, and tuberculosis

Figure 7. 1 Current vaccines typically consist of either: A Figure 7.1 Current vaccines typically consist of either: A. A heat or chemically-killed (inactivated) form of an infectious agent or B. A live, nonvirulent (attenuated) form of an infectious agent.

Traditional vaccines and their drawbacks Traditional vaccines are either inactivated or attenuated infectious agents (bacteria or viruses) injected into an antibody-producing organism to produce immunity Drawbacks include: inability to grow enough agent, safety concerns, reversion of attenuated strains, incomplete inactivation, limited shelf life, may require refrigeration to maintain potency, only 5 major manufacturers of traditional vaccines (Sanofi, Merck, Glaxo-SmithKline, Pfizer, Novartis)

How do you make a traditional vaccine? See: http://www.cdc.gov/flu/about/season/flu-season-2016-2017.htm For information about H1N1 Flu (Swine Flu), see: http://www.cdc.gov/H1N1FLU/

Recombinant DNA technology can create better, safer, reliable vaccines Genes or portions of genes encoding major antigenic determinants can be cloned in expression vectors and large amounts of the product purified or chemically synthesized for use as a Subunit Vaccine or Peptide Vaccine, respectively A gene(s) encoding a major antigenic determinant(s) can be introduced and expressed in humans or mammals (DNA Vaccine) Immunologically active, non-infectious agents can be produced by deleting virulence genes (Attenuated Vaccine) A gene(s) encoding a major antigenic determinant(s) can be cloned and expressed a benign carrier virus or bacteria (Vector Vaccine)

Figure 7.2 Structure of a typical animal virus. Note that capsid and envelope proteins can elicit neutralizing antibodies. Vaccines that use such components of a pathogen rather than the whole pathogen are called Subunit Vaccines. .

Figure 7.4 Development of a subunit vaccine against Herpes Simplex Virus (HSV), using cloned HSV envelope glycoprotein D gene and Chinese Hamster Ovary (CHO) cells.

A similar approach was used to create a subunit vaccine against foot-and-mouth disease virus (FMDV) and Human Papillovmavirus (HPV) FMDV has a devastating effect on cattle and swine The successful subunit vaccine is based on the expression of the capsid viral protein 1 (VP1) as a fusion protein with the bacteriophage MS2 replicase protein in E. coli The FMDV genome consists of a 8kb ssRNA; a cDNA was made to this genome and the VP1 region identified immunologically (see Fig. 12.4) A subunit vaccine (Gardasil) was developed against Human Papillomavirus; this virus causes genital warts and is associated with the development of cervical cancers; used the capsid proteins from four HPVs (Read BOX on p. 355) See https://www.ispot.tv/ad/Ap1V/merck-hpv-vaccination

Table 7.3

Figure 7. 16 A peptide vaccine for malaria Figure 7.16 A peptide vaccine for malaria. The “final peptide” is currently being tested in clinical trials.

Figure 7.20 Genetic immunization: DNA vaccines

Attenuated Vaccines Attenuated vaccines traditionally use nonpathogenic bacteria or viruses related to their pathogenic counterparts Genetic manipulation may also be used to create attenuated vaccines by deleting a key disease causing gene from the pathogenic agent Example: deleting the glycoprotein D gene from HSV-2 Example: the enterotoxin gene for the A1 peptide of V. cholerae, the causative agent of cholera, was deleted; the resulting bacteria was non-pathogenic and yet elicits a good immunoprotection (some side effects noted however)

Figure 7.26 Genetic modification of Herpes Simplex Virus-2 (HSV-2) to create an Attenuated Vaccine against HSV-1.

Figure 7. 28 Genetic engineering of attenuated strain of V Figure 7.28 Genetic engineering of attenuated strain of V. cholerae by removing the gene sequence encoding the A1 peptide.

Vector Vaccines Here the idea is to use a benign virus or bacteria as a vector to carry your favorite antigen gene from some pathogenic agent The vaccinia virus is one such benign virus and has been used to express such antigens Properties of the vaccinia virus: 187kb dsDNA genome, encodes ~200 different proteins, replicates in the cytoplasm with its own replication machinery, broad host range, stable for years after drying However, the virus genome is very large and lacks unique RE sites, so gene encoding specific antigens must be introduced into the viral genome by homologous recombination Attenuated strains of Salmonella, a human intestinal bacteria, have also been used as vectors to express antigen genes from pathogenic agents

Figure 7.31 General method for making a Vector Vaccine using Vaccinia Virus. A. Clone the antigen gene in a plasmid and B. Recombination with Vaccinia Virus.

Figure 7.41 Using Salmonella as a vector to express the cholera toxin B protein

Figure 7. 44 Monoclonal Antibody Passive Immunity Figure 7.44 Monoclonal Antibody Passive Immunity. A humanized or human monoclonal antibody made against the stem region of hemagglutinin could be administered to humans to provide immunity to a wide range of influenza viruses.