BACKGROUND: Canine leishmaniasis (CanL) is a severe chronic disease caused by Leishmania infantum and transmitted by sand flies of which the main vector in the Western part of the Mediterranean basin is Phlebotomus perniciosus. Previously, an immunochromatographic test (ICT) was proposed to allow rapid evaluation of dog exposure to P. perniciosus. In the present study, we optimized the prototype and evaluated the detection accuracy of the ICT in field conditions. Possible cross-reactions with other hematophagous arthropods were also assessed. METHODOLOGY/PRINCIPAL FINDINGS: The ICT was optimized by expressing the rSP03B protein in a HEK293 cell line, which delivered an increased specificity (94.92%). The ICT showed an excellent reproducibility and inter-person reliability, and was optimized for use with whole canine blood which rendered an excellent degree of agreement with the use of serum. Field detectability of the ICT was assessed by screening 186 dogs from different CanL endemic areas with both the SGH-ELISA and the ICT, and 154 longitudinally sampled dogs only with the ICT. The ICT results corresponded to the SGH-ELISA for most areas, depending on the statistical measure used. Furthermore, the ICT was able to show a clear seasonal fluctuation in the proportion of bitten dogs. Finally, we excluded cross-reactions between non-vector species and confirmed favorable cross-reactions with other L. infantum vectors belonging to the subgenus Larroussius. CONCLUSIONS/SIGNIFICANCE: We have successfully optimized the ICT, now also suitable to be used with whole canine blood. The test is able to reflect the seasonal fluctuation in dog exposure and showed a good detectability in a field population of naturally exposed dogs, particularly in areas with a high seroprevalence of bitten dogs. Furthermore, our study showed the existence of favorable cross-reactions with other sand fly vectors thereby expanding its use in the field.

• MeSH
• Insect Vectors parasitology   physiology   MeSH
• Immunoassay methods   MeSH
• Leishmania infantum physiology   MeSH
• Leishmaniasis blood   diagnosis   parasitology   veterinary   MeSH
• Mice, Inbred BALB C MeSH
• Dog Diseases blood   diagnosis   parasitology   MeSH
• Phlebotomus parasitology   physiology   MeSH
• Dogs MeSH
• Animals MeSH
• Check Tag
• Dogs MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Research Support, Non-U.S. Gov't MeSH

BACKGROUND: Hosts repeatedly bitten by sand flies develop antibodies against sand fly saliva and screening of these immunoglobulins can be employed to estimate the risk of Leishmania transmission, to indicate the feeding preferences of sand flies, or to evaluate the effectiveness of vector control campaigns. Previously, antibodies to sand fly saliva were detected using whole salivary gland homogenate (SGH) or recombinant proteins, both of which also have their disadvantages. This is the first study on sand flies where short peptides designed based on salivary antigens were successfully utilized for antibody screening. METHODOLOGY/PRINCIPAL FINDINGS: Specific IgG was studied in hosts naturally exposed to Phlebotomus orientalis, the main vector of Leishmania donovani in East Africa. Four peptides were designed by the commercial program EpiQuest-B, based on the sequences of the two most promising salivary antigens, yellow-related protein and ParSP25-like protein. Short amino acid peptides were synthesised and modified for ELISA experiments. Specific anti-P. orientalis IgG was detected in sera of dogs, goats, and sheep from Ethiopia. The peptide OR24 P2 was shown to be suitable for antibody screening; it correlated positively with SGH and its specificity and sensitivity were comparable or even better than that of previously published recombinant proteins. CONCLUSIONS/SIGNIFICANCE: OR24 P2, the peptide based on salivary antigen of P. orientalis, was shown to be a valuable tool for antibody screening of domestic animals naturally exposed to P. orientalis. We suggest the application of this promising methodology using species-specific short peptides to other sand fly-host combinations.

• MeSH
• Enzyme-Linked Immunosorbent Assay methods   MeSH
• Immunoglobulin G blood   MeSH
• Goats MeSH
• Sheep MeSH
• Peptides immunology   MeSH
• Phlebotomus immunology   MeSH
• Mass Screening methods   MeSH
• Antibodies blood   MeSH
• Dogs MeSH
• Sensitivity and Specificity MeSH
• Salivary Proteins and Peptides immunology   MeSH
• Animals MeSH
• Check Tag
• Dogs MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Ethiopia MeSH
• Names of Substances
• Immunoglobulin G MeSH
• Peptides MeSH
• Antibodies MeSH
• Salivary Proteins and Peptides MeSH

BACKGROUND: Phlebotomus orientalis is a vector of Leishmania donovani, the causative agent of life threatening visceral leishmaniasis spread in Eastern Africa. During blood-feeding, sand fly females salivate into the skin of the host. Sand fly saliva contains a large variety of proteins, some of which elicit specific antibody responses in the bitten hosts. To evaluate the exposure to sand fly bites in human populations from disease endemic areas, we tested the antibody reactions of volunteers' sera against recombinant P. orientalis salivary antigens. METHODOLOGY/PRINCIPAL FINDINGS: Recombinant proteins derived from sequence data on P. orientalis secreted salivary proteins, were produced using either bacterial (five proteins) or mammalian (four proteins) expression systems and tested as antigens applicable for detection of anti-P. orientalis IgG in human sera. Using these recombinant proteins, human sera from Sudan and Ethiopia, countries endemic for visceral leishmaniasis, were screened by ELISA and immunoblotting to identify the potential markers of exposure to P. orientalis bites. Two recombinant proteins; mAG5 and mYEL1, were identified as the most promising antigens showing high correlation coefficients as well as good specificity in comparison to the whole sand fly salivary gland homogenate. Combination of both proteins led to a further increase of correlation coefficients as well as both positive and negative predictive values of P. orientalis exposure. CONCLUSIONS/SIGNIFICANCE: This is the first report of screening human sera for anti-P. orientalis antibodies using recombinant salivary proteins. The recombinant salivary proteins mYEL1 and mAG5 proved to be valid antigens for screening human sera from both Sudan and Ethiopia for exposure to P. orientalis bites. The utilization of equal amounts of these two proteins significantly increased the capability to detect anti-P. orientalis antibody responses.

• MeSH
• Enzyme-Linked Immunosorbent Assay MeSH
• Insect Proteins genetics   immunology   MeSH
• Immunoglobulin G immunology   MeSH
• Insect Bites and Stings immunology   parasitology   MeSH
• Humans MeSH
• Phlebotomus genetics   immunology   physiology   MeSH
• Recombinant Proteins genetics   immunology   MeSH
• Salivary Proteins and Peptides genetics   immunology   MeSH
• Saliva immunology   MeSH
• Antibody Formation MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Africa, Eastern MeSH
• Names of Substances
• Insect Proteins MeSH
• Immunoglobulin G MeSH
• Recombinant Proteins MeSH
• Salivary Proteins and Peptides MeSH

BACKGROUND: Canine leishmaniosis (CanL) is an important zoonotic parasitic disease, endemic in the Mediterranean basin. In this region, transmission of Leishmania infantum, the etiological agent of CanL, is through the bite of phlebotomine sand flies. Therefore, monitoring host-vector contact represents an important epidemiological tool, and could be used to assess the effectiveness of vector-control programmes in endemic areas. Previous studies have shown that canine antibodies against the saliva of phlebotomine sand flies are specific markers of exposure to Leishmania vectors. However, this method needs to be further validated in natural heterogeneous dog populations living in CanL endemic areas. METHODS: In this study, 176 dogs living in 12 different locations of an L. infantum endemic area in north-east Spain were followed for 14 months. Blood samples were taken at 5 pre-determined time points (February, August and October 2016; January and April 2017) to assess the canine humoral immune response to whole salivary gland homogenate (SGH) and to the single salivary 43 kDa yellow-related recombinant protein (rSP03B) of Phlebotomus perniciosus, a proven vector of L. infantum naturally present in this region. Simultaneously, in all dogs, L. infantum infection status was assessed by serology. The relationship between anti-SGH and anti-rSP03B antibodies with the sampling month, L. infantum infection and the location was tested by fitting multilevel linear regression models. RESULTS: The dynamics of canine anti-saliva IgG for both SGH and rSP03B followed the expected trends of P. perniciosus activity in the region. Statistically significant associations were detected for both salivary antigens between vector exposure and sampling month or dog seropositivity to L. infantum. The correlation between canine antibodies against SGH and rSP03B was moderate. CONCLUSIONS: Our results confirm the frequent presence of CanL vectors in the study area in Spain and support the applicability of SGH- and rSP03B-based ELISA tests to study canine exposure to P. perniciosus in L. infantum endemic areas.

• Keywords
• Canine leishmaniosis, Longitudinal study, Markers of exposure, North-east Spain, Phlebotomus perniciosus, Saliva proteins,
• MeSH
• Endemic Diseases veterinary   MeSH
• Insect Vectors parasitology   MeSH
• Immunity, Humoral MeSH
• Immunoglobulin G analysis   MeSH
• Leishmania infantum isolation & purification   MeSH
• Leishmaniasis blood   parasitology   veterinary   MeSH
• Longitudinal Studies MeSH
• Dog Diseases diagnosis   immunology   parasitology   MeSH
• Phlebotomus immunology   MeSH
• Antibodies, Protozoan blood   MeSH
• Antibodies blood   MeSH
• Dogs immunology   parasitology   MeSH
• Seasons MeSH
• Salivary Proteins and Peptides immunology   MeSH
• Salivary Glands chemistry   parasitology   MeSH
• Saliva immunology   microbiology   parasitology   MeSH
• Animals MeSH
• Check Tag
• Dogs immunology   parasitology   MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Spain epidemiology   MeSH
• Names of Substances
• Immunoglobulin G MeSH
• Antibodies, Protozoan MeSH
• Antibodies MeSH
• Salivary Proteins and Peptides MeSH

BACKGROUND: Canine leishmaniasis (CanL) is a zoonotic disease, caused by Leishmania infantum and transmitted by Phlebotomus perniciosus in the Mediterranean basin. Previously, an ELISA based on the P. perniciosus salivary protein SP03B was proposed as a valid tool to screen for canine exposure to sand fly bites across regions endemic for CanL. Although this approach is useful in laboratory settings, a practical tool for immediate application in the field is needed. In this study we propose the rSP03B sero-strip, the first immunochromatographic test (ICT) in the field of vector exposure able to rapidly screen dogs living in endemic areas for the presence of P. perniciosus and to aid in the evaluation of vector control programs. METHODOLOGY/PRINCIPAL FINDINGS: The ICT was prepared using the bacterially expressed recombinant protein rSP03B as antigen. For test optimization, pre-immune sera from non-bitten laboratory-bred Beagles were used as negative controls. In order to validate the test, sera from laboratory-bred Beagles experimentally exposed to P. perniciosus bites were used as positive controls. Additionally, all samples were tested by ELISA using whole salivary gland homogenate (SGH) and the rSP03B protein as antigen. An almost perfect degree of agreement was found between the ICT and the SGH-ELISA. Furthermore, the newly proposed rSP03B sero-strip showed a sensitivity of 100% and a specificity of 86.79%. CONCLUSIONS/SIGNIFICANCE: We developed a simple and rapid ICT based on the P. perniciosus rSP03B salivary protein, able to replace the standard ELISA used in previous studies. Our rSP03B sero-strip showed to be highly sensitive and specific in the detection of antibodies (IgG) against P. perniciosus saliva. In the future, this test can be employed during large-scale epidemiological studies of CanL in the Mediterranean area to evaluate the efficacy of vector control programs.

• MeSH
• Time Factors MeSH
• Chromatography, Affinity veterinary   MeSH
• Enzyme-Linked Immunosorbent Assay methods   MeSH
• Insect Vectors MeSH
• Insect Proteins MeSH
• Insect Bites and Stings immunology   veterinary   MeSH
• Leishmania infantum MeSH
• Dog Diseases diagnosis   parasitology   MeSH
• Phlebotomus immunology   MeSH
• Dogs MeSH
• Reagent Strips MeSH
• Sensitivity and Specificity MeSH
• Serologic Tests veterinary   MeSH
• Zoonoses MeSH
• Animals MeSH
• Check Tag
• Dogs MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Insect Proteins MeSH
• Reagent Strips MeSH

BACKGROUND: Leishmaniases are parasitic diseases present worldwide that are transmitted to the vertebrate host by the bite of an infected sand fly during a blood feeding. Phlebotomine sand flies inoculate into the mammalian host Leishmania parasites embedded in promastigote secretory gel (PSG) with saliva, which is composed of a diverse group of molecules with pharmacological and immunomodulatory properties. METHODS AND FINDINGS: In this review, we focus on 3 main aspects of sand fly salivary molecules: (1) structure and composition of salivary glands, including the properties of salivary molecules related to hemostasis and blood feeding, (2) immunomodulatory properties of salivary molecules and the diverse impacts of these molecules on leishmaniasis, ranging from disease exacerbation to vaccine development, and (3) use of salivary molecules for field applications, including monitoring host exposure to sand flies and the risk of Leishmania transmission. Studies showed interesting differences between salivary proteins of Phlebotomus and Lutzomyia species, however, no data were ever published on salivary proteins of Sergentomyia species. CONCLUSIONS: In the last 15 years, numerous studies have characterized sand fly salivary proteins and, in parallel, have addressed the impact of such molecules on the biology of the host-sand fly-parasite interaction. The results obtained shall pave the way for the development of field-application tools that could contribute to the management of leishmaniasis in endemic areas.

• MeSH
• Leishmania immunology   MeSH
• Psychodidae parasitology   physiology   MeSH
• Salivary Proteins and Peptides immunology   metabolism   MeSH
• Saliva immunology   parasitology   MeSH
• Feeding Behavior * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Salivary Proteins and Peptides MeSH

Yellow-related proteins (YRPs) present in sand fly saliva act as affinity binders of bioamines, and help the fly to complete a bloodmeal by scavenging the physiological signals of damaged cells. They are also the main antigens in sand fly saliva and their recombinant form is used as a marker of host exposure to sand flies. Moreover, several salivary proteins and plasmids coding these proteins induce strong immune response in hosts bitten by sand flies and are being used to design protecting vaccines against Leishmania parasites. In this study, thirty two 3D models of different yellow-related proteins from thirteen sand fly species of two genera were constructed based on the known protein structure from Lutzomyia longipalpis. We also studied evolutionary relationships among species based on protein sequences as well as sequence and structural variability of their ligand-binding site. All of these 33 sand fly YRPs shared a similar structure, including a unique tunnel that connects the ligand-binding site with the solvent by two independent paths. However, intraspecific modifications found among these proteins affects the charges of the entrances to the tunnel, the length of the tunnel and its hydrophobicity. We suggest that these structural and sequential differences influence the ligand-binding abilities of these proteins and provide sand flies with a greater number of YRP paralogs with more nuanced answers to bioamines. All these characteristics allow us to better evaluate these proteins with respect to their potential use as part of anti-Leishmania vaccines or as an antigen to measure host exposure to sand flies.

• MeSH
• Phylogeny MeSH
• Glycosylation MeSH
• Insect Proteins chemistry   metabolism   MeSH
• Protein Conformation MeSH
• Ligands MeSH
• Models, Molecular MeSH
• Psychodidae * MeSH
• Amino Acid Sequence MeSH
• Saliva metabolism   MeSH
• Static Electricity MeSH
• Binding Sites MeSH
• Hydrogen Bonding MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Insect Proteins MeSH
• Ligands MeSH