Protection of mice from lethal flaviviral encephalitis by adoptive transfer of splenic cells from donors infected with live virus.

C3H/RV mice, which are genetically resistant to lethal flaviviral infection were susceptible to lethal challenge with Banzi virus after they were given rabbit antiserum to mouse thymocytes. Congenic C3H/He mice, which are genetically susceptible to lethal flaviviral infection, were protected from lethal challenge with Banzi virus by adoptive immunization with splenic cells from syngeneric or congenic donor mice infected with live virus, as measured by amelioration of clinical disease, death rates, and viral replication. Protection was dependent on thymus cells; mice given immune splenic cells treated with rabbit antiserum to mouse brain and complement had high death rates. Transfer of protection was dependent on time and the dosage of splenic cells. Immune splenic cells from c3h/rv donors were, on a cell-for-cell basis, more effective than immune splenic cells from C3H/He donors in preventing viral replication, encephalitis, and death in C3H/He recipients.