A comparative study of different Leishmania tropica isolates from Iran: correlation between infectivity and
Abstract:
Five isolates of Leishmania tropica from southwest Iran were studied to identify correlates among human disease, animal infectivity, and surface biochemistry. Clinical patterns of the disease in humans differed. One striking strain, LT-249, produced a small dry lesion which did not heal during four years of observation. Infectivity of these L. tropica for mice was correlated with lectin agglutination patterns and interaction with macrophages. There was also a significant difference among the five isolates regarding infectivity for BALB/c mice; isolate LT-249 was not infective whereas all the others were. All isolates agglutinated with Concanavalin A (Con A), Ricinus communis and soybean agglutinin but not with four other lectins listed. However, Leishmania isolate LT-249 showed much poorer agglutination with all lectins than did the other four isolates. Two isolates were selected for detailed study of attachment to macrophages, one, LT-249, which was not infective and one, LT-252, which was infective for BALB/c mice. The number of promastigotes which attached to macrophages in vitro was the same, but the mechanism of attachment differed since only the LT-252 bound predominantly by Con A-mannose receptor interaction. These results indicate a correlation among animal infectivity, lectin agglutination, and promastigote-macrophage attachment. In particular one isolate of L. tropica which caused prolonged infection in humans was not infective in BALB/c mice, showed poor agglutination with lectins, and bound to macrophages by a different mechanism than did other isolates from the same region.
Insights
Surface biochemistry of Leishmania tropica isolates correlates with disease severity and infectivity in mice. Specific lectin agglutination patterns and macrophage attachment mechanisms distinguish less infective strains, offering insights into disease pathogenesis.
Area of Science:
- Parasitology
- Immunology
- Biochemistry
Background:
- Leishmania tropica causes cutaneous leishmaniasis with variable clinical presentations.
- Understanding the factors influencing Leishmania tropica infectivity and pathogenesis is crucial for disease control.
Purpose of the Study:
- To investigate the correlation between human disease manifestations, animal infectivity, and surface biochemistry of Leishmania tropica isolates.
- To characterize the differences in lectin agglutination and macrophage interaction among various Leishmania tropica strains.
Main Methods:
- Analysis of five Leishmania tropica isolates from southwest Iran.
- Assessment of clinical patterns in human infections.
- Determination of infectivity in BALB/c mice.
- Lectin agglutination assays using Concanavalin A, Ricinus communis, and soybean agglutinin.
- In vitro studies of promastigote attachment to macrophages.
Main Results:
- Clinical disease patterns varied among isolates, with one strain (LT-249) causing prolonged, non-healing lesions.
- Isolate LT-249 exhibited significantly lower infectivity in BALB/c mice compared to other isolates.
- All isolates agglutinated with certain lectins, but LT-249 showed weaker agglutination.
- While attachment numbers to macrophages were similar, LT-252 (infective) predominantly used Concanavalin A-mannose receptor interaction, unlike LT-249.
Conclusions:
- Leishmania tropica infectivity in mice correlates with lectin agglutination patterns and promastigote-macrophage attachment mechanisms.
- A specific isolate causing prolonged human infection demonstrated distinct biochemical and infectivity characteristics.
- These findings highlight the heterogeneity of Leishmania tropica and its implications for disease pathogenesis.
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