The FML-vaccine (Leishmune) against canine visceral leishmaniasis: a transmission blocking vaccine.
Transmission blocking vaccines are one of the control strategies for vector-transmitted protozoan diseases. Antibodies raised in the vaccinated host prevent the development of the parasite in the insect vector, interrupting the epidemiological cycle. The FML antigen of Leishmania donovani in combination with saponin (FML-vaccine and Leishmune) induced 92-97% of protections against zoonotic visceral leishmaniasis. We assayed the ability of FML to inhibit Leishmania donovani and Leishmania chagasi procyclic promastigote-binding to dissected Lutzomyia longipalpis midguts. We found a dose-dependent inhibition, more pronounced on L. donovani (80%) than on L. chagasi promastigotes (p<0.001). On the other hand, the Fab-IgG serum fraction of Leishmune vaccinated dogs (IgG2 predominant), also inhibited parasite binding in a dose-response (p<0.0001) with an equally potent effect against L. donovani or L. chagasi (p = 0.061). The transmission blocking properties of the Leishmune vaccine was also assessed by an in vivo membrane assay, with sand flies fed with 1.5 x 10(7) amastigotes, human blood and, vaccinated or normal control dog sera. Significantly higher values were found in rate of infection (p<0.025) and intensity of infection (number of parasites/insect) (p<0.05) of control sand flies, making a very reduced infection index (20.7%) in the vaccine group. Our results disclosed that the Leishmune vaccine is a TBV, and that the dog antibodies present in sera, even 12 months after vaccination, lead to a significant effective protection of 79.3%.
Saraiva
Elvira M
EM
Instituto de Microbiologia, Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro (UFRJ), CCS, Cidade Universitária, Ilha do Fundão, Caixa Postal 68040, CEP 21941-590, Rio de Janeiro, RJ, Brazil.
de Figueiredo Barbosa
André
A
Santos
Fernanda Nunes
FN
Borja-Cabrera
Gulnara Patrícia
GP
Nico
Dirlei
D
Souza
Lucieri Olegário Pereira
LO
de Oliveira Mendes-Aguiar
Carolina
C
de Souza
Edilma Paraguai
EP
Fampa
Patrícia
P
Parra
Luciana Ellner
LE
Menz
Ingrid
I
Dias
Jaime Galvão
JG
de Oliveira
Sandra Maria
SM
Palatnik-de-Sousa
Clarisa Beatriz
CB
D000818:Animals; D004283:Dog Diseases / Q000517:prevention & control* / Q000635:transmission; D004285:Dogs; D005260:Female; D007106:Immune Sera / Q000276:immunology*; D037102:Lectins / Q000276:immunology*; D007893:Leishmania donovani / Q000276:immunology*; D018314:Leishmania infantum / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000517:prevention & control / Q000635:transmission / Q000662:veterinary*; D016052:Protozoan Vaccines / Q000276:immunology*; D011576:Psychodidae / Q000469:parasitology*
D007106:Immune Sera; D037102:Lectins; D016052:Protozoan Vaccines; C027112:fucose-binding lectin