Immunity to Lutzomyia whitmani Saliva Protects against Experimental Leishmania braziliensis Infection.
BACKGROUND
Previous works showed that immunization with saliva from Lutzomyia intermedia, a vector of Leishmania braziliensis, does not protect against experimental infection. However, L. braziliensis is also transmitted by Lutzomyia whitmani, a sand fly species closely related to Lu. intermedia. Herein we describe the immune response following immunization with Lu. whitmani saliva and the outcome of this response after L. braziliensis infection.


RESULTS
BALB/c mice immunized with Lu. whitmani saliva developed robust humoral and cellular immune responses, the latter characterized by an intense cellular infiltrate and production of IFN-γ and IL-10, by both CD4+ and CD8+ cells. Mice immunized as above and challenged with L. braziliensis plus Lu. whitmani saliva displayed significantly smaller lesions and parasite load at the challenge site. This protection was associated with a higher (p<0.05) IFN-γ production in response to SLA stimulation. Long-term persisting immunity was also detected in mice immunized with Lu. whitmani saliva. Furthermore, individuals residing in an endemic area for cutaneous leishmaniasis (CL) presented antibody responses to Lu. whitmani saliva. However CL patients, with active lesions, displayed a lower humoral response to Lu. whitmani saliva compared to individuals with subclinical Leishmania infection.


CONCLUSIONS
Pre-exposure to Lu. whitmani saliva induces protection against L. braziliensis in a murine model. We also show that Lu. whitmani salivary proteins are immunogenic in naturally exposed individuals. Our results reinforce the importance of investigating the immunomodulatory effect of saliva from different species of closely related sand flies.
Escritório Técnico Regional, Fundação Oswaldo Cruz (FIOCRUZ), Teresina, Piauí, Brazil.
Regis
R
Gomes
Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Salvador, Bahia, Brazil.
Katrine
K
Cavalcanti
Escritório Técnico Regional, Fundação Oswaldo Cruz (FIOCRUZ), Teresina, Piauí, Brazil.
Clarissa
C
Teixeira
Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Salvador, Bahia, Brazil.
Augusto M
AM
Carvalho
Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Salvador, Bahia, Brazil.
Paulo S
PS
Mattos
Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Salvador, Bahia, Brazil.
Juqueline R
JR
Cristal
Federal University of Bahia School of Medicine, Salvador, Brazil.
Aline C
AC
Muniz
Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Salvador, Bahia, Brazil.
José Carlos
JC
Miranda
Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Salvador, Bahia, Brazil.|INCT - Instituto de Investigação em Imunologia, São Paulo, Brazil.
Camila I
http://orcid.org/0000-0002-7868-5164
CI
de Oliveira
Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Salvador, Bahia, Brazil.|INCT - Instituto de Investigação em Imunologia, São Paulo, Brazil.|Universidade Federal da Bahia, Salvador, Brazil.
Aldina
A
Barral
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007114:Immunization; D007074:Immunoglobulin G / Q000097:blood; D056747:Immunomodulation; D007303:Insect Vectors / Q000276:immunology* / Q000469:parasitology; D007371:Interferon-gamma / Q000276:immunology; D016753:Interleukin-10 / Q000276:immunology; D007892:Leishmania braziliensis / Q000276:immunology*; D016773:Leishmaniasis, Cutaneous / Q000276:immunology* / Q000469:parasitology / Q000517:prevention & control; D051379:Mice; D008807:Mice, Inbred BALB C; D059208:Parasite Load; D011446:Prospective Studies; D011576:Psychodidae / Q000276:immunology* / Q000469:parasitology; D012463:Saliva / Q000737:chemistry / Q000276:immunology*; D012471:Salivary Proteins and Peptides / Q000276:immunology*
D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D012471:Salivary Proteins and Peptides; D016753:Interleukin-10; D007371:Interferon-gamma