Characterization of Populations of Promastigotes of Leishmania donovani1

Abstract

Promastigotes of Leismania donovani cultured for either 3 or 10 days in vitro and inoculated intracardially into golden hamsters with an equal number of organisms from either population showed a 7‐fold difference in infectivity when compared at both 10 to 16 days post‐infection. Reproducible histochemical staining for the promastigote enzymes glucose‐6‐phosphate dehydrogenase (G6PDH) and peptidase after polyacrylamide gel electrophoresis showed two isoelectric variants of G6PDH (Bands 1 and 2) that displayed a 45% decrease (Band 1) and a 60% increase (Band 2) in total activity when 3‐ and 10‐day‐old promastigores were compared. Peptidase activity, present in a single band, increased 7‐fold in 10‐day‐old promastigotes. A decrease in the lectin‐induced agglutination of promastigotes by castor bean agglutinin (RCA₆₀), specific for D‐galactose and N‐acetyl‐D‐galactosamine, was seen when 3‐ and 10‐day‐old promastigotes are compared. Antisera raised against sonicated 10‐day‐old promastigotes showed a unique precipitin band between the antiserum and sonicated 10‐day‐old promastigotes not found between the antiserum and sonicated 3‐day‐old promastigotes.