The following mechanisms may underlie the profile of an anti-HBc–negative HBV infection: 1) Studies in the woodchuck model showed that infection with very low doses may lead to primary occult infections which result in T cell–mediated protection but no detectable antibody formation.20 Although the amount of HBV may have been low, this mechanism is probably not present here because there is no resolution of the infection and no hint for protective T-cell immunity in the recipient. The gene discussed is KRT88P; the disease is infection.