The Papaya lethal yellowing vir us (PL YV), known for its capacity to naturally infect papaya ( Carica papaya L.), promoted a humoral immune response in mice immunized via oral and nasal application. ELISA and immunodiffusion tests detected specific antibodies in sera of animals orally immunized with a crude extract of infected leaves and with purified virus, and in sera of animals immunized by nasal route with...