Leishmania (Viannia) braziliensis transfectants overexpressing the miniexon gene lose virulence in vivo.
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.
de Toledo
Juliano Simões
JS
Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil.
Junqueira dos Santos
André F
AF
Rodrigues de Moura
Tatiana
T
Antoniazi
Simone Aparecida
SA
Brodskyn
Cláudia
C
Indiani de Oliveira
Camila
C
Barral
Aldina
A
Cruz
Angela Kaysel
AK
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
D020038:RNA, Spliced Leader