The accomplishment from the two main projects of the unit are: 1) Discovery of two sand fly salivary vaccine candidates that produce a strong and long lasting cellular immune response in dogs. Dogs are the main reservoir of visceral leishmaniasis in Europe and South America. We developed an experimental model that mimics the natural exposure of dogs to sand fly bites and explored the immune responses to salivary proteins from the sand fly Lutzomyia longipalpis, the vector of visceral leishmaniasis in South America. Lu. longipalpis salivary proteins induced a DTH response at the bite site in the skin of dogs following repeated exposures to sand flies. This skin response is a surrogate of cellular immune response and a first screen marker of protection against Leishmania infection in rodent models. Two of 35 salivary proteins (LJM17 and LJL143) from the vector sand fly Lutzomyia longipalpis, identified using a novel approach termed reverse antigen screening, elicited strong cellular immunity in dogs. Immunization with either molecule induced high IgG2 antibody levels and significant IFN- production following in vitro stimulation of PBMC with salivary gland homogenate. Importantly, saliva stimulated lymphocytes from immunized dogs efficiently killed Leishmania infantum chagasi within autologous macrophages. These findings suggest that inclusion of these salivary molecules in anti-Leishmania canine vaccines would enhance their efficiency in protecting dogs from visceral leishmaniasis. 2) Identification of biological activities from novel salivary molecules of unknown sequence or function. Most sand fly salivary proteins are novel and do not have an assigned biological function. Soluble recombinant proteins were produced in a mammalian expression system to test potential biological activities. We identified a potent serotonin binding protein, a potent anticoagulant, a tryptase inhibitor and an anti-complement protein from the saliva of L. longipalpis. These molecules have the potential for use in the treatment of a variety of human ailments. This work not only demonstrates that the anticoagulant inhibitor of sand flies is a novel prothrombinase inhibitor, but also makes it a potential active drug to correct pro-coagulant disorders in human medicine. C3b-inhibitors could be potential new drugs that correct human diseases related to complement such as auto-immune diseases and post-surgery complications due to complement. 3) Discovery of Markers of Exposure Specific to Bites of Lutzomyia longipalpis, the Vector of Leishmania infantum chagasi in Latin America Leishmania parasites are transmitted by the bite of an infected vector sand fly that injects salivary molecules into the host skin during feeding. Certain salivary molecules can produce antibodies and can be used as an indicator of exposure to a vector sand fly and potentially the disease it transmits. To identify potential specific markers of vector exposure, we produced nine different recombinant salivary proteins from Lu. longipalpis and tested for their recognition by individuals exposed to another human-biting sand fly, Lu. intermedia, that transmits cutaneous leishmaniasis and commonly occurs in the same endemic areas as Lu. longipalpis. Two salivary proteins (named LJM17 and LJM11) were recognized only by humans exposed to Lu. longipalpis, suggesting they are immunogenic proteins and may be useful in epidemiological studies. The identification of specific salivary proteins as potential markers of exposure to vector sand flies will increase our understanding of vector human interaction, bring new insights to vector control, and in some instances act as an indicator for risk of acquiring disease. 4) Characterization of the salivary proteins from the sand fly Phlebotomus arabicus. We performed a transcriptomic analysis of the old world sand fly Phlebotomus arabicus and analyzed the repertoire of molecules in the saliva of this insect, performed bioinformatics analyses and some biological assays to validate the presence of powerful biological activities and antigenic molecules.

Project Start
Project End
Budget Start
Budget End
Support Year
8
Fiscal Year
2010
Total Cost
$1,421,968
Indirect Cost
City
State
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Asojo, Oluwatoyin A; Kelleher, Alan; Liu, Zhuyun et al. (2017) Structure of SALO, a leishmaniasis vaccine candidate from the sand fly Lutzomyia longipalpis. PLoS Negl Trop Dis 11:e0005374
Carvalho, Augusto M; Fukutani, Kiyoshi F; Sharma, Rohit et al. (2017) Seroconversion to Lutzomyia intermedia LinB-13 as a biomarker for developing cutaneous leishmaniasis. Sci Rep 7:3149
Roatt, Bruno Mendes; Aguiar-Soares, Rodrigo Dian de Oliveira; Reis, Levi Eduardo Soares et al. (2017) A Vaccine Therapy for Canine Visceral Leishmaniasis Promoted Significant Improvement of Clinical and Immune Status with Reduction in Parasite Burden. Front Immunol 8:217
Kelly, Patrick H; Bahr, Sarah M; Serafim, Tiago D et al. (2017) The Gut Microbiome of the Vector Lutzomyia longipalpis Is Essential for Survival of Leishmania infantum. MBio 8:
Maruyama, Sandra R; Garcia, Gustavo R; Teixeira, Felipe R et al. (2017) Mining a differential sialotranscriptome of Rhipicephalus microplus guides antigen discovery to formulate a vaccine that reduces tick infestations. Parasit Vectors 10:206
Mendes-Sousa, Antonio F; Queiroz, Daniel C; Vale, Vladimir F et al. (2016) An Inhibitor of the Alternative Pathway of Complement in Saliva of New World Anopheline Mosquitoes. J Immunol 197:599-610
Hosseini-Vasoukolaei, Nasibeh; Mahmoudi, Ahmad-Reza; Khamesipour, Ali et al. (2016) Seasonal and Physiological Variations of Phlebotomus papatasi Salivary Gland Antigens in Central Iran. J Arthropod Borne Dis 10:39-49
Solcà, Manuela S; Andrade, Bruno B; Abbehusen, Melissa Moura Costa et al. (2016) Circulating Biomarkers of Immune Activation, Oxidative Stress and Inflammation Characterize Severe Canine Visceral Leishmaniasis. Sci Rep 6:32619
Abdeladhim, Maha; V Coutinho-Abreu, Iliano; Townsend, Shannon et al. (2016) Molecular Diversity between Salivary Proteins from New World and Old World Sand Flies with Emphasis on Bichromomyia olmeca, the Sand Fly Vector of Leishmania mexicana in Mesoamerica. PLoS Negl Trop Dis 10:e0004771
Fiuza, Jacqueline Araújo; Dey, Ranadhir; Davenport, Dwann et al. (2016) Intradermal Immunization of Leishmania donovani Centrin Knock-Out Parasites in Combination with Salivary Protein LJM19 from Sand Fly Vector Induces a Durable Protective Immune Response in Hamsters. PLoS Negl Trop Dis 10:e0004322

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