A new enzymatic variant of Leishmania (Leishmania) forattinii isolated from Proechimys iheringi (Rodentia, Echimydae) in Espírito Santo, Brazil.

Abstract

Taxonomic studies of leishmanial isolates fromthe New World indicate tremendous diversitywithin this genus (E Cupolillo et al. 1994 Am JTrop Med Hyg 50: 296-311). A number of newLeishmania species from sylvan areas of theNeotropics have been described recently. Some ofthose parasites are associated with disease in hu-mans; others appear to be restricted to lower or-ders of mammals, such as rodents and edentates(G Grimaldi et al. 1989 Am J Trop Med Hyg 41:687-725). However, some of the latter parasitesmay yet be shown capable of causing human dis-ease, particularly in persons with altered cellularimmune responses.During a survey of potential reservoir hosts ofLeishmania done in the State of Espirito Santo, Bra-zil (1982-1985), three leishmanial parasites (des-ignated with stock codes MPRO/BR/82/RV203,MPRO/BR/82/RV228, and MPRO/BR/85/RV260)were isolated from skin lesion samples taken fromspiny-rats, Proechimys iheringi (Rodentia,Echimydae), captured in a secondary forest locatedin the municipality of Viana (A Falqueto et al. 1985Mem Inst Oswaldo Cruz 80: 497). In studies us-ing an indirect radioimmune binding assay (RIA)and a large panel of monoclonal antibodies (Mabs)derived for selected species of Leishmania , the iso-lates were characterized as members of the L.mexicana complex. These strains were differentfrom those species infective to humans, in that theyreacted with either the L.(L.) amazonensis or L.(L.) mexicana specific MAbs. Furthermore, thiswas also the case with cloned organisms from twostocks showing that they were not mixed popula-tions of Leishmania (G Grimaldi et al. 1987 Am JTrop Med Hyg 36: 270-287). This group of dis-tinct parasites presented, however, similarserodeme patterns in relation to the new recentlydescribed species of the Leishmania subgenus, L.(L.) forattinii (E Yoshida et al. 1993 Mem InstOswaldo Cruz 88: 397-406).The latter parasite was isolated from sylvaticreservoir hosts (Didelphis marsupialis aurita andP. iheringi denigratus ) captured on regions endemicfor American cutaneous leishmaniasis in Brazil,respectively in the municipalities of Conchas, SaoPaulo (E Yoshida et al. 1979 Rev Inst Med Trop SPaulo 21: 110-113) and Tres Bracos, Bahia (ABarreto et al. 1985 Rev Soc Bras Med Trop 18:243-246). The general morphology and the growthcharacteristics in vitro of the new species were simi-lar to those of other L. mexicana complex para-sites. Here we have further studied the Espirito Santoisolates using additional techniques for the char-acterization of Leishmania . The molecular proce-dures used for typing the strains (isoenzyme elec-trophoresis, blot enzyme binding assay usingMAbs, restriction endonuclease fragment patternsof k-DNA, and molecular karyotype analysis) havebeen described in detail in previous publications(Yoshida et al. 1979, 1983 loc. cit. , Cupolillo et al.1994 loc. cit., A Franco et al. 1997 Mem InstOswaldo Cruz 92: 63-68).Results of electrophoretic analysis were basedon the following enzymatic loci, namely: glucose-6-phosphate dehydrogenase (G6PDH), malate de-hydrogenase (MDH), isocitrate dehydrogenase(IDHNADP), 6-phosphogluconate dehydrogenase(6PGDH), nucleotidase (NH1 and NH2), glucosephosphate isomerase (GPI), phosphoglucomutase(PGM), proline dipeptidase (PEPD), leucine pep-tidase (PEP2), malic enzyme (ME), mannose phos-phate isomerase (MPI), and aconitate hydratase(ACON). The enzyme profiles of the selected iso-lated signature MPRO/BR/82/RV228, which rep-resents the poorly defined group of parasites from