Leishmania (Viannia) braziliensis: biological behavior in golden hamsters of isolates from Argentine patients.
This study reports intraspecific variations of native isolates of Leishmania (Viannia) braziliensis from patients with leishmaniasis from Salta, Argentina. These isolates induced skin lesions in golden hamsters, initially showing rapid development, reaching their largest size between 28 and 35 days postinfection (PI). Thereafter, the infections were self-limiting and total regression was observed at 80-150 days PI. The majority of the native isolates were characterized by low infectivity in the experimental animals, and a classic pattern of dissemination to systemic organs was established. However, unusual features for L. braziliensis were displayed by two isolates; one showed evidence of high infectivity in hamsters characterized by a short prepatent period and larger, severe and persistent lesions at the inoculation site. The other isolate, of low infectivity, showed cutaneous metastasis and recurrent systemic dissemination in the same animals, suggesting dissociation between infectivity and pathogenicity. Metastasis has been frequently described in hamsters infected with L. (V) guyanensis and L. (V) panamensis, but not in infections induced by L. (V) braziliensis, as was observed in this study. Active and/or regressive histopathologic lesions were observed, depending on the stage of the infection. An exudative and mixed inflammatory pattern with microabscesses and necrotic areas was observed during early infection, while well-defined granulomas and collagen formation were the predominant features detected at a later time. Amastigotes were easily detected in the tissues, although in low numbers. Schaumann bodies were always detected. The characterization of the unique features of these native isolates, and the verification of their reproducibility in vitro and in vivo will be useful tools in tests related to immunoprophylaxis and chemotherapy.
Sinagra
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Instituto Nacional de Parasitologia Dr. Mario Fatala Chaben, Buenos Aires, Argentina.
Riarte
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Luna
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Campanini
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Segura
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D000818:Animals; D001118:Argentina; D006224:Cricetinae; D004195:Disease Models, Animal; D006099:Granuloma / Q000469:parasitology / Q000473:pathology; D006801:Humans; D007892:Leishmania braziliensis / Q000302:isolation & purification / Q000472:pathogenicity*; D016773:Leishmaniasis, Cutaneous / Q000276:immunology / Q000469:parasitology* / Q000473:pathology; D008264:Macrophages / Q000469:parasitology; D008647:Mesocricetus; D009336:Necrosis; D009666:Nose; D012867:Skin / Q000276:immunology / Q000469:parasitology* / Q000473:pathology