But how could an “intrinsic” gene cause sudden seroconversion and hepatitis?724 Genes, after all, do not typically flicker on and off at will. Blumberg’s beautiful theory about genetic variation had been slain by an ugly fact. Au, he realized, could not mark an inherent variation in a human gene. In fact, Au was soon found to be neither a human protein nor a blood antigen. Au was a piece of a viral protein floating in the blood, the sign of an infection.
