Table 3 Safety concerns of the vaccine strain
From: Live bacterial vaccines – a review and identification of potential hazards
Systemic disturbance | Systemic infection |
Conversion from avirulent to virulent bacterium | |
Translocation to organs | |
Disturbance of digestive processes | |
Inhibition of bacterial production of nutrients | |
Immune system | Absorption of allergens through the intestinal epithelium |
Induction of tolerance to pathogen instead of immunity | |
Induction or potentiation of autoimmunity | |
Bacterial mimicry of self-antigen | |
Metabolites | Production of harmful/undesired metabolites including enzymatic activities |
Breakdown of chemicals to toxic metabolites | |
Implications for natural flora in GI tract | Permanent colonisation of cell substrate in the intestine |
Gene/plasmid transfer to host's indigenous flora | |
"Competitive exclusion" of indigenous flora | |
Unintentional transferral of cell substrate | Unintentional transfer to other individuals |
Unintentional transfer to and viability/propagation in environments other than the intestines | |
Contamination | Extraneous or perceived adventitious DNA components should be removed (possibility of oncogenicity). |