Editing Openai/680845c9-c944-8012-bafb-fa1bab1e9277 (section)

==== Your framework demands that: ====
* A virus be directly proven to cause disease by a clean, causally closed experiment

That would be ideal. But modern virology, like much of biology, builds proof through convergence:
* Genomic structure (e.g., complete viral genome)
* Particle imaging (e.g., EM and cryo-EM)
* Reproducible symptom induction in animals or cell cultures
* Immunological response (antibody production, neutralization)
* Real-world epidemiology and transmission
* Targeted interventions (e.g., antivirals, vaccines) that work

In this framework:
* The virus is real if it behaves like one in all measurable ways — even if the single-chain “pure particle → disease in host” experiment isn’t performed in humans due to ethical limitations.

It’s not perfect, but it’s practical — and it meets the standards of biomedical evidence in the modern world.