Éditeur(s) : HAL CCSD Instituto Oswaldo Cruz, Ministério da Saúde
Résumé : International audience
Leishmania are protozoan parasites that show remarkable diversity, as revealed by the various clinical forms of leishmaniasis,which can range from mild skin lesions to severe metastatic cutaneous/mucosal lesions. The exact nature andextent of Leishmania phenotypic diversity in establishing infection is not fully understood. In order to try to understandsome aspects of this diversity, we subcutaneously infected BALB/c mice with first and second generation subclones of aL. amazonensis strain isolated from a patient (BA125) and examined in vivo lesion growth rate and antimony susceptibility.In vivo fast-, medium- and slow-growing subclones were obtained; moreover, fast-growing subclones could generateslow-growing subclones and inversely, revealing the continuous generation of diversity after passage into mice. Noantimony-resistant subclone appeared, probably a rare occurrence. By tagging subclone cells with a L. amazonensisgenomic cosmid library, we found that only a very small number of founding cells could produce lesions. Leishmaniaclones transfected with in vivo selected individual cosmids were also diverse in terms of lesion growth rate, revealing thecosmid-independent intrinsic characteristics of each clone. Our results suggest that only a few of the infecting parasitesare able to grow and produce lesions; later, within the cell mixture of each lesion, there coexist several parasite populationswith different potentialities to grow lesions during the next infection round. This may reflect a sort of programmedheterogeneity of individual parasites, favoring the survival of some individuals in various environmental conditions.
ISSN: 0074-0276

hal-01557855
https://hal-univ-perp.archives-ouvertes.fr/hal-01557855
DOI : 10.1590/0074-02760160280

Éditeur(s) : HAL CCSD Instituto Oswaldo Cruz, Ministério da Saúde
Résumé : International audience
Leishmania are protozoan parasites that show remarkable diversity, as revealed by the various clinical forms of leishmaniasis, which can range from mild skin lesions to severe metastatic cutaneous/mucosal lesions. The exact nature and extent of Leishmania phenotypic diversity in establishing infection is not fully understood. In order to try to understand some aspects of this diversity, we subcutaneously infected BALB/c mice with first and second generation subclones of a L. amazonensis strain isolated from a patient (BA125) and examined in vivo lesion growth rate and antimony susceptibility. In vivo fast-, medium- and slow-growing subclones were obtained; moreover, fast-growing subclones could generate slow-growing subclones and inversely, revealing the continuous generation of diversity after passage into mice. No antimony-resistant subclone appeared, probably a rare occurrence. By tagging subclone cells with a L. amazonensis genomic cosmid library, we found that only a very small number of founding cells could produce lesions. Leishmania clones transfected with in vivo selected individual cosmids were also diverse in terms of lesion growth rate, revealing the cosmid-independent intrinsic characteristics of each clone. Our results suggest that only a few of the infecting parasites are able to grow and produce lesions; later, within the cell mixture of each lesion, there coexist several parasite populations with different potentialities to grow lesions during the next infection round. This may reflect a sort of programmed heterogeneity of individual parasites, favoring the survival of some individuals in various environmental conditions.
ISSN: 0074-0276

hal-01489008
https://hal-univ-perp.archives-ouvertes.fr/hal-01489008

Éditeur(s) : HAL CCSD European Centre for Disease Prevention and Control
Résumé : International audience
Leishmaniasis is endemic in southern Europe, and in other European countries cases are diagnosed in travellers who have visited affected areas both within the continent and beyond. Prompt and accurate diagnosis poses a challenge in clinical practice in Europe. Different methods exist for identification of the infecting Leishmania species. Sixteen clinical laboratories in 10 European countries, plus Israel and Turkey, conducted a study to assess their genotyping performance. DNA from 21 promastigote cultures of 13 species was analysed blindly by the routinely used typing method. Five different molecular targets were used, which were analysed with PCR-based methods. Different levels of identification were achieved, and either the Leishmania subgenus, species complex, or actual species were reported. The overall error rate of strains placed in the wrong complex or species was 8.5%. Various reasons for incorrect typing were identified. The study shows there is considerable room for improvement and standardisation of Leishmania typing. The use of well validated standard operating procedures is recommended, covering testing, interpretation, and reporting guidelines. Application of the internal transcribed spacer 1 of the rDNA array should be restricted to Old World samples, while the heat-shock protein 70 gene and the mini-exon can be applied globally.
ISSN: 1560-7917

hal-01460743
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01460743
DOI : 10.2807/1560-7917.ES.2016.21.49.30418
PUBMED : 27983510

Éditeur(s) : HAL CCSD Instituto Oswaldo Cruz, Ministério da Saúde
Résumé : International audience
Leishmania are protozoan parasites that show remarkable diversity, as revealed by the various clinical forms of leishmaniasis, which can range from mild skin lesions to severe metastatic cutaneous/mucosal lesions. The exact nature and extent of Leishmania phenotypic diversity in establishing infection is not fully understood. In order to try to understand some aspects of this diversity, we subcutaneously infected BALB/c mice with first and second generation subclones of a L. amazonensis strain isolated from a patient (BA125) and examined in vivo lesion growth rate and antimony susceptibility. In vivo fast-, medium- and slow-growing subclones were obtained; moreover, fast-growing subclones could generate slow-growing subclones and inversely, revealing the continuous generation of diversity after passage into mice. No antimony-resistant subclone appeared, probably a rare occurrence. By tagging subclone cells with a L. amazonensis genomic cosmid library, we found that only a very small number of founding cells could produce lesions. Leishmania clones transfected with in vivo selected individual cosmids were also diverse in terms of lesion growth rate, revealing the cosmid-independent intrinsic characteristics of each clone. Our results suggest that only a few of the infecting parasites are able to grow and produce lesions; later, within the cell mixture of each lesion, there coexist several parasite populations with different potentialities to grow lesions during the next infection round. This may reflect a sort of programmed heterogeneity of individual parasites, favoring the survival of some individuals in various environmental conditions.
ISSN: 0074-0276

hal-01489009
https://hal-univ-perp.archives-ouvertes.fr/hal-01489009

Éditeur(s) : HAL CCSD Instituto Oswaldo Cruz, Ministério da Saúde
Résumé : International audience
Leishmania are protozoan parasites that show remarkable diversity, as revealed by the various clinical forms of leishmaniasis, which can range from mild skin lesions to severe metastatic cutaneous/mucosal lesions. The exact nature and extent of Leishmania phenotypic diversity in establishing infection is not fully understood. In order to try to understand some aspects of this diversity, we subcutaneously infected BALB/c mice with first and second generation subclones of a L. amazonensis strain isolated from a patient (BA125) and examined in vivo lesion growth rate and antimony susceptibility. In vivo fast-, medium- and slow-growing subclones were obtained; moreover, fast-growing subclones could generate slow-growing subclones and inversely, revealing the continuous generation of diversity after passage into mice. No antimony-resistant subclone appeared, probably a rare occurrence. By tagging subclone cells with a L. amazonensis genomic cosmid library, we found that only a very small number of founding cells could produce lesions. Leishmania clones transfected with in vivo selected individual cosmids were also diverse in terms of lesion growth rate, revealing the cosmid-independent intrinsic characteristics of each clone. Our results suggest that only a few of the infecting parasites are able to grow and produce lesions; later, within the cell mixture of each lesion, there coexist several parasite populations with different potentialities to grow lesions during the next infection round. This may reflect a sort of programmed heterogeneity of individual parasites, favoring the survival of some individuals in various environmental conditions.
ISSN: 0074-0276

hal-01489007
https://hal-univ-perp.archives-ouvertes.fr/hal-01489007