Vaccination

6.8 Summary of Section 6

Features of host-pathogen interactions that present a major challenge to vaccine development include:

  1. A permanent reservoir of infection in other animals (zoonoses) or in carrier individuals, and free-living pathogens in the environment.

  2. Rapid mutation of pathogen genomes resulting in antigenic variation, antigenic disguise with host proteins, multiple strains, or different antigens at different stages of the pathogen's life cycle.

  3. Effective countermeasures in pathogens to evade or inhibit immune responses against them including decoy proteins, and inhibition of lysosome fusion complement activation or antigen presentation.

  4. Immunogenic regions located away from regions that are essential for pathogen survival and replication.

  5. Weak or absent immunogenicity of pathogen antigens, which also creates scientific uncertainty about what constitutes an effective immune response.