The immune system fails because of a cascade effect. Our adaptive immune system (antibodies) depends on activation signals from the innate system. Because the innate system's receptors can't bind to mirror molecules, the initial alarm is never sounded, preventing the entire defensive chain of command from launching.

The industry's focus on antibodies, which are easy to generate, may be a case of technology dictating the science. Dr. Radvanyi argues that natural ligand-receptor interactions, which often rely on lower affinity and higher avidity, could offer a more nuanced and effective way to modulate immune pathways than high-affinity agonist antibodies.

The fundamental immune mechanisms that mirror life bypasses (pattern recognition receptors) are conserved across the tree of life. This means plants and insects are also vulnerable, making mirror life a catastrophic threat to agriculture and entire ecosystems, not just vertebrates.

Unlike typical pathogens, mirror bacteria would be immune to their natural predators like viruses (bacteriophages). This advantage could allow them to proliferate uncontrollably in soil and oceans, creating a permanent environmental reservoir for infection and potentially outcompeting essential natural microbes.

Researchers can avoid the immense risk of creating mirror life for study. Instead, they can develop mirror-image countermeasures (like mirror antibodies) and test them against normal bacteria. If effective, the 'normal' version of that countermeasure would work against mirror life, allowing for safe R&D.

A common objection—that mirror life would starve—is incorrect. The human body is rich in achiral nutrients (molecules without a mirror-image form), like acetate and glycerol. Mirror bacteria can readily metabolize these, allowing them to grow rapidly without needing to consume our body's chiral molecules.

While creating a bioweapon may be cheaper than defending against it, biology is inherently defense-dominant. Pathogens are vulnerable to physical barriers, filtration, heat, and UV light. Their small size is a weakness, and unlike intelligent adversaries, they cannot strategically penetrate defenses, giving defenders a fundamental advantage.

Marine cyanobacteria, essential to the carbon cycle, are controlled by viruses. A mirror version would be immune, potentially leading to explosive population growth. This could act as a massive, unpredictable carbon sink, sequestering enough atmospheric CO2 to catastrophically alter the climate and risk an ice age.

Current biosecurity screens for threats by matching DNA sequences to known pathogens. However, AI can design novel proteins that perform a harmful function without any sequence similarity to existing threats. This necessitates new security tools that can predict a protein's function, a concept termed "defensive acceleration."