V. Evaluation of Cross-Immunity against Type 1 Dengue Fever in Human Subjects Convalescent from Subclinical Natural Japanese Encephalitis Virus Infection and Vaccinated with 17D Strain Yellow Fever Vaccine
Sera from 16 patients suffering from oral, nasal, oro-nasal or laryngeal types of Sudan mucosal leishmaniasis were tested against leishmanial antigen by three immunodiagnostic methods. Reactive soluble antigen was prepared from sonicated promastigotes. When tested against undiluted sera, in all 16 cases it gave easily visible precipitin lines in agar gel in both immunodiffusion and counterimmunoelectrophoresis tests. In immunofluorescence tests, with promastigote slide antigen and using the indirect antibody technique, the sera were positive at serum dilutions ranging from 1:200 to 1:6,400. There was no correlation between fluorescent titer levels and the strength of precipitin reactions in the immunodiffusion and counterimmunoelectrophoresis tests. Sixteen normal sera gave negative results in all three tests.