Safety
Summary / Intro
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Lab Safety
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Product and patient safety
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Genetic and ecological safety
Summary
As our engineered probiotic is a living biotherapeutic product, meant to be administered directly into the human gut, it comes with safety considerations that go beyond those of a standard lab strain. Since the bacterium is meant to survive, act, and eventually be cleared from a living host, we need to ensure that it behaves predictably while inside the gut, cannot cause harm if it escapes into the environment, and does not pass its engineered traits on to the native gut microbiota. We approached this through three layers:
- In-Host Control governs what the bacterium does while it is still in the gut. This includes a gut gate, which restricts effector expression to the anaerobic gut environment using a hypoxia-responsive promoter, and a feedback-responsive expression mechanism, which aims to further restrict expression to only occur when testosterone is present above a set threshold. Beyond controlling expression itself, we also considered colonization control by weighing whether our probiotic should be transient, requiring repeat dosing, or self-limiting by design.
- Environmental Biocontainment ensures the organism cannot survive or spread if it escapes the gut. This covers auxotrophy (engineering a dependency on a nutrient not available outside controlled conditions), kill-switches (including quorum-sensing-based and CRISPR-based approaches), and genetic firewalling (such as amber-suppression semantic firewalls, which make the organism's genetic code incompatible with natural systems). Across these strategies, we also considered the genetic stability of our safety circuits and how we ensure kill-switches and other mechanisms aren't lost over time through mutation under selection pressure.
- GMO Regulations also plays an important role in our design choices. In the EU, this span contained laboratory use (Directive 2009/41/EC), potential human administration as a medicinal product (Directive 2001/83/EC), environmental release (Directive 2001/18/EC), environmental risk assessment for GMO-containing medicinal products (EMA guidelines), and international movement of living modified organisms (the Cartagena Protocol).
For each strategy, we researched multiple possible approaches, compared them against our project's specific constraints, and selected the combination that best balances safety, feasibility, and relevance to AnTigone as a testosterone-lowering gut therapeutic.
GMO regulations
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