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Targeted gene deletion in Leishmania major identifies leishmanolysin (GP63) as a virulence factor
Phalgun B Joshi1, Ben L Kelly, Shaden Kamhawi
1Department of Medical Genetics, Jack Bell Research Centre, University of British Columbia and Immunity and Infection Research Centre, Vancouver Hospital, 2660 Oak Street, BC, V6H 3Z6, Vancouver, Canada. robm@interchange.ubc.ca
Abstract:
Leishmanolysin, the Leishmania surface metalloproteinase of 63 kDa (GP63) has been described as a parasite virulence factor and is involved in the direct interaction of promastigotes and host macrophage receptors and interaction with the complement cascade. To study the role of leishmanolysin in the pathogenesis and virulence of Leishmania major, targeted gene replacement was used to delete the entire 20 kb region containing all seven leishmanolysin genes (gp63 genes 1-7). The resulting L. major leishmanolysin deficient mutants showed normal development inside the sand fly vector, however, promastigotes recovered from sand flies or from culture showed an increase in sensitivity to complement-mediated lysis and a delay in lesion formation in BALB/c animals. The phenotypic differences could be significantly improved by expression of a cloned leishmanolysin gene. These results demonstrate that leishmanolysin is a vital virulence factor in Leishmania pathogenesis.
Insights
Leishmanolysin (GP63) is crucial for Leishmania major virulence. Deleting its genes increased parasite susceptibility to host defenses and delayed disease, confirming GP63
Area of Science:
- Parasitology
- Molecular Biology
- Immunology
Background:
- Leishmanolysin (GP63) is a Leishmania surface metalloproteinase.
- It is implicated as a parasite virulence factor.
- GP63 mediates interactions with host cells and the complement system.
Purpose of the Study:
- To investigate the role of leishmanolysin in Leishmania major pathogenesis and virulence.
- To understand the specific functions of GP63 in host-parasite interactions.
Main Methods:
- Targeted gene replacement was employed to delete all seven leishmanolysin (gp63) genes in Leishmania major.
- Leishmanolysin-deficient mutants were analyzed for development, infectivity, and immune evasion.
- Phenotypic rescue was achieved by reintroducing a leishmanolysin gene.
Main Results:
- Leishmania major mutants lacking leishmanolysin (GP63) developed normally within the sand fly vector.
- Promastigotes deficient in GP63 exhibited increased sensitivity to complement-mediated lysis.
- Lesion formation in BALB/c mice was delayed in the absence of leishmanolysin.
- Re-expression of leishmanolysin restored wild-type phenotypes.
Conclusions:
- Leishmanolysin (GP63) is an essential virulence factor for Leishmania major.
- GP63 plays a critical role in protecting the parasite from host immune responses, particularly complement-mediated lysis.
- Targeting GP63 could be a potential strategy for leishmaniasis treatment.