u/Better_Preference236

I'm but a lowly chemist and I know this is highly speculative, but is it possible for an extraterrestrial pathogen to ever be dangerous? Assume for the sake of argument that the aliens it infects are still based on nucleic acids, proteins, etc, but not necessarily the same ones we are. I can't imagine anything virus-like could ever be compatible enough to kill us, but what about the alien equivalent of a bacterium? Is there any organism on earth fastidious enough to infect a novel host with completely different nutrients? Is there a plausible mechanism by which an alien pathogen could kill us despite differences in nutrient composition, chirality, amino acid composition, etc?

I'm but a lowly chemist and I know this is highly speculative, but is it possible for an extraterrestrial pathogen to ever be dangerous? Assume for the sake of argument that the aliens it infects are still based on nucleic acids, proteins, etc, but not necessarily the same ones we are. I can't imagine anything virus-like could ever be compatible enough to kill us, but what about the alien equivalent of a bacterium? Is there any organism on earth fastidious enough to infect a novel host with completely different nutrients? Is there a plausible mechanism by which an alien pathogen could kill us despite differences in nutrient composition, chirality, amino acid composition, etc?