A New Virus of Ducks Interfering with Development of Malaria Parasite (Plasmodium lophurae).

Abstract

In the course of passage of P. lophurae in ducklings by weekly transfer of infected blood, a contaminating infective agent appeared which inhibited malarial infection and caused rapid death of ducks. The agent was present in plasma of infected birds and was readily separated from malaria parasites. It was a filterable virus, producing, in ducks inoculated with appropriate doses, a rapidly fatal disease characterized especially by enlargement and necrosis of the spleen. This spleen necrosis virus was neutralized by serum from a recovered immune duck but not by antiserum to duck hepatitis virus. In ducklings simultaneously inoculated with P. lophurae and a suitable dose of spleen necrosis virus, development of malaria parasites was retarded and many of them appeared abnormal.