6.8 Summary of Section 6
Features of host-pathogen interactions that present a major challenge to vaccine development include:
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A permanent reservoir of infection in other animals (zoonoses) or in carrier individuals, and free-living pathogens in the environment.
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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.
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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.
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Immunogenic regions located away from regions that are essential for pathogen survival and replication.
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Weak or absent immunogenicity of pathogen antigens, which also creates scientific uncertainty about what constitutes an effective immune response.