Characterization of Kenyan isolates of Leishmania by Isoenzyme Electrophoresis and Infectivity to mice.

Abstract

In this study, Leishmania major and Leishmania strains from Kenya were cloned by limiting dilution. Population homogeneity of the strains was determined by determining the infectivity of the clones in Balb/e mice and their isoenzyme profiles. Characterization of L. donovani isolates from kalaazar endemic areas in Kenya was done by cellulose acetate electrophoresis to determine strain variation. High temperature adaptation of L. major strain was done by repeated intraperitoneal passages in Balb/c mice to determine whether this parasite ean viseeralize without causing a cutaneous lesion. Cloning of L. major strain CNLB 144) and L. donovani strain CNLB 065) , was done by limiting dilution. The obtained clones were used to infect Balb/c mice. Results demonstrated that L. major strain is not homogenous but consists of a genetically mixed population. This was confirmed by finding of clones, that although had the same zymodeme. showed a difference in infectivity in mice. One clone was very

virulent and resulted in severe ulceration of the nasal area of mice. L. donovani clones also showed population homogeneity with reference to isoenzymes but a difference in infectivity to mice. Only clone-l was infective to Balb/c mice. These results are of great

significance to leishmaniasis vaccine production. Presence of clonal homogeneity of a strain suggests that one type of vaccine can be used in the treatment and control of leishmaniasis. Cellulose acetate electrophoresis of 15 L. donovani isolates from Baringo, Turkana and Machakos Districts in Kenya revealed low levels of variation in the parasite genome. Only one isolate, NLB 659 from Baringo District showed a different banding pattern for isocitrate dehydrogenase (ICD) . This suggests that there is no intraspecific variation of L. donovani strains in Kenya or if it occurs, its in very low level .This is very important in the treatment of visceral leishmaniasis because L. donovani has been known to cause both kalaazar and post- kala-azar dermal leishmaniasis. Intraperitoneal 144) resulted in visce~alization of the parasite. (NLB The passaging of L. major strain incubation period became shorter with each successive passage. The parasite behaved like viscerotropic L.donovani since no conspicuous cutaneous lesion was formed at the site of inoculation. Isoenzyme electrophoresis of this viscerotropic L. major showed enzyme profiles similar to those of the original stock of L.major except for the enzymes glucose phophate isomerase (GPI) and glucose 6 phosphate dehydrogenase (G6PD). 3-4 months post-infection. some parasites

disseminated to the footpads and caused lesions. This viscerotropism of L. ma}or in Balb/c mice emphasizes the need to characterize Leishmania parasites particularly those isolated from rodents before making conclusions of their identity.