title: Leishmania (Viannia) braziliensis transfectants overexpressing the miniexon gene lose virulence in vivo.
abstract: The miniexon gene has a central role in the processing of polycistronic pre-mRNA of kinetoplastids. It is added to the 5' extremity of each mRNA, supplying the 5'-capped structure to the molecule. Previous studies in Leishmania (Leishmania) major showed that the overexpression of the miniexon array attenuates the virulence of the parasite in in vivo assays. The results presented here extend those findings to Viannia subgenus. Leishmania (Viannia) braziliensis was transfected with a cosmid harboring a tandem array of one hundred miniexon gene copies and then characterized by Northern blot analysis. The overexpression of the exogenous gene was confirmed and its effect on the virulence of L. (V.) braziliensis was investigated in hamsters. In BALB/c mice we could not detect parasites during the course of 15 weeks of infection. In addition, hamsters infected with transfectants overexpressing the miniexon gene exhibited only a minor footpad swelling of late onset and failed to develop progressive lesion, these attenuated parasites could be recovered from the inoculation site 1 year after infection. The persistence of parasites in the host indicates that a stable line overexpressing the miniexon may be tested as live vaccine against leishmaniasis.
authors.affiliation: Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Juliano Simões
authors.initials: JS
authors.lastname: de Toledo
authors.forename: André F
authors.initials: AF
authors.lastname: Junqueira dos Santos
authors.forename: Tatiana
authors.initials: T
authors.lastname: Rodrigues de Moura
authors.forename: Simone Aparecida
authors.initials: SA
authors.lastname: Antoniazi
authors.forename: Cláudia
authors.initials: C
authors.lastname: Brodskyn
authors.forename: Camila
authors.initials: C
authors.lastname: Indiani de Oliveira
authors.forename: Aldina
authors.initials: A
authors.lastname: Barral
authors.forename: Angela Kaysel
authors.initials: AK
authors.lastname: Cruz
mesh_terms: D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D005091:Exons / Q000235:genetics* / Q000502:physiology; D006801:Humans; D007892:Leishmania braziliensis / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology / Q000473:pathology*; D008264:Macrophages / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D020038:RNA, Spliced Leader / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation; D014774:Virulence
chemical_list: D020038:RNA, Spliced Leader