title: Virulence loss and amastigote transformation failure determine host cell responses to Leishmania mexicana.
abstract: The effect of alterations in virulence and transformation by long-term in vitro culture of Leishmania mexicana promastigotes on infectivity and immune responses was investigated. Fresh parasite cultures harvested from Balb/c mice were passaged 20 times in vitro. Infectivity was decreased and was completely avirulent after 20 passages. The qPCR results showed a down-regulation of GP63, LPG2, CPC, CPB2, CPB2.8, CHT1, LACK and LDCEN3 genes after passage seven concomitant with a reduced and absence of infectivity by passages seven and 20, respectively. Parasites at passages one and 20 are referred to as virulent and avirulent, respectively. The growth of avirulent and virulent parasite was affected by conditioned media derived from macrophages or monocytes infected with parasites for 2 h. Giemsa staining showed the failure of avirulent but not virulent parasites to transform to the amastigote stage in infected host cells with both virulent and avirulent modulating the expression of CCL-22, Tgad51, Cox2, IL-1, IL-10, TGF-β, TNF-α, Rab7, Rab9 and A2 genes; virulent but not avirulent L. mexicana significantly up-regulated Th2-associated cytokines, but down-regulated Rab7 and Rab9 gene expression. In conclusion, a model for L. mexicana is reported, which is of potential value in studying host-parasite interaction.
authors.affiliation: Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, UK.
authors.forename: K S
authors.initials: KS
authors.lastname: Ali
authors.forename: R C
authors.initials: RC
authors.lastname: Rees
authors.forename: C
authors.initials: C
authors.lastname: Terrell-Nield
authors.forename: S A
authors.initials: SA
authors.lastname: Ali
mesh_terms: D000818:Animals; D017077:Culture Media, Conditioned; D016207:Cytokines / Q000235:genetics; D005786:Gene Expression Regulation; D017125:Genes, Protozoan; D006790:Host-Parasite Interactions; D006801:Humans; D007894:Leishmania mexicana / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000472:pathogenicity*; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology; D008264:Macrophages / Q000276:immunology* / Q000469:parasitology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009000:Monocytes / Q000469:parasitology; D010587:Phagocytosis; D012692:Serial Passage; D059467:Transcriptome; D020298:U937 Cells; D014774:Virulence / Q000235:genetics
chemical_list: D017077:Culture Media, Conditioned; D016207:Cytokines
keywords: Leishmania spp - parasite; cytokine - immunological terms; gene expression - tools and techniques; immune modulation - immunological terms; macrophage - cell; monocytes - cell