Compounds in sand fly saliva elicit specific immune responses that may play a role in the establishment of canine Leishmania infection. Although canine antibodies to anti-sand fly saliva antigens have been extensively studied, little is known about cellular immune responses against Phlebotomus perniciosus salivary proteins. This study aimed to explore humoral and T-cell-mediated immunity against P. perniciosus salivary proteins in dogs (n = 85) from Mallorca (Spain), a leishmaniosis-endemic area, and find correlations with demographic (age, sex, and breed) and parasite-specific immunological parameters. Anti-sand fly saliva IgG was examined using a P. perniciosus whole salivary gland homogenate (SGH) ELISA and recombinant salivary protein rSP03B ELISA. Interferon gamma (IFN-γ) release whole blood assays with L. infantum soluble antigen (LSA), SGH, and rSP03B were also performed. Positive correlations were found between IgG levels in the SGH and rSP03B tests and between concentrations of SGH IFN-γ and rSP03B IFN-γ. While concentrations of SGH IFN-γ and rSP03B IFN-γ were low and produced only by a minority of dogs (less than 20%), high levels and frequencies of LSA IFN-γ as well as anti-saliva IgG for SGH and rSP03B were detected in a majority of dogs (61% and 75%, respectively). LSA IFN-γ levels were positively correlated with age and Leishmania-specific antibodies. In conclusion, dogs from a leishmaniosis-endemic area presented high humoral immunity against P. perniciosus salivary proteins, but their cellular immunity to these proteins was low and less frequent.

• Keywords
• Leishmania infantum, anti-saliva antibodies, canine, recombinant salivary proteins, specific P. perniciosus saliva IFN-γ,
• MeSH
• Immunity, Cellular * MeSH
• Endemic Diseases MeSH
• Insect Proteins * immunology   MeSH
• Immunity, Humoral * MeSH
• Immunoglobulin G blood   immunology   MeSH
• Interferon-gamma MeSH
• Leishmaniasis * immunology   veterinary   epidemiology   MeSH
• Dog Diseases * immunology   parasitology   epidemiology   MeSH
• Phlebotomus * immunology   MeSH
• Dogs MeSH
• Salivary Proteins and Peptides * immunology   MeSH
• T-Lymphocytes * immunology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Dogs MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Spain epidemiology   MeSH
• Names of Substances
• Insect Proteins * MeSH
• Immunoglobulin G MeSH
• Interferon-gamma MeSH
• Salivary Proteins and Peptides * MeSH

Phlebotomus perniciosus is a major vector of Leishmania infantum in the Mediterranean. While the seroprevalence of leishmaniosis in Spanish dogs and cats has been studied, data on the exposure of cats to P. perniciosus bites under natural conditions without repellents is limited. Stray cats could serve as sentinels for L. infantum and P. perniciosus exposure. This study analyzed sera from 204 apparently healthy stray cats, collected from January 2021 to January 2022, for antibodies against P. perniciosus saliva and L. infantum parasites. Anti-sand fly antibodies were detected in 40.69% of cats using an ELISA with the recombinant salivary protein SP03B of P. perniciosus. Seroprevalence of L. infantum infection was 23.52% by Western blot and 27.41% by ELISA, with an overall seroprevalence of 40.69% (95% CI 34.18-47.54%). This is the first assessment of antibody response to P. perniciosus saliva and L. infantum in naturally exposed stray cats in Spain. Further research is needed to examine the salivary antigens recognized by cats and to explore the relationship between P. perniciosus exposure and L. infantum infection severity in cats.

• Keywords
• Cat, ELISA, Leishmania infantum, Phlebotomus perniciosus, serology, western blotting,
• MeSH
• Enzyme-Linked Immunosorbent Assay veterinary   MeSH
• Insect Vectors parasitology   MeSH
• Cats MeSH
• Leishmania infantum * immunology   MeSH
• Leishmaniasis, Visceral * veterinary   epidemiology   immunology   MeSH
• Cat Diseases * epidemiology   parasitology   immunology   MeSH
• Phlebotomus * parasitology   immunology   MeSH
• Antibodies, Protozoan * blood   MeSH
• Seroepidemiologic Studies MeSH
• Animals MeSH
• Check Tag
• Cats MeSH
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Spain epidemiology   MeSH
• Names of Substances
• Antibodies, Protozoan * MeSH

Antibodies against Phlebotomus perniciosus sandfly salivary gland homogenate (SGH) and recombinant protein rSP03B, sandfly-borne Toscana virus (TOSV), Sandfly Fever Sicilian virus (SFSV) and Leishmania, as well as DNA of the latter parasite, were investigated in 670 blood samples from 575 human donors in Murcia Region, southeast Spain, in 2017 and 2018. The estimated SGH and rSP03B seroprevalences were 69% and 88%, respectively, although correlation between test results was relatively low (ρ = 0.39). Similarly, TOSV, SFSV and Leishmania seroprevalences were 26%, 0% and 1%, respectively, and Leishmania PCR prevalence was 2%. Prevalences were significantly greater in 2017, overdispersed and not spatially related to each other although both were positively associated with SGH but not to rSP03B antibody optical densities, questioning the value of the latter as a diagnostic marker for these infections in humans.

• Keywords
• Leishmania infantum, anti-saliva antibodies, blood donors, sandflies, sandfly fever sicilian virus, toscana virus,
• MeSH
• Blood Donors MeSH
• Leishmania infantum * MeSH
• Leishmaniasis * parasitology   veterinary   MeSH
• Humans MeSH
• Phlebotomus * parasitology   MeSH
• Antibodies MeSH
• Psychodidae * MeSH
• Recombinant Proteins MeSH
• Sandfly fever Naples virus * genetics   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Spain epidemiology   MeSH
• Names of Substances
• Antibodies MeSH
• Recombinant Proteins MeSH

Phlebotomus argentipes is a predominant vector of Leishmania donovani, the protozoan parasite causing visceral leishmaniasis in the Indian subcontinent. In hosts bitten by P. argentipes, sand fly saliva elicits the production of specific anti-salivary protein antibodies. Here, we have utilised these antibodies as markers of human exposure to P. argentipes in a visceral leishmaniasis endemic area in Pabna district, Bangladesh. The use of whole salivary gland homogenate as an antigen to detect these antibodies has several limitations, therefore it is being superseded by the use of specific recombinant salivary proteins. We have identified three major P. argentipes salivary antigenic proteins recognised by sera of bitten humans, expressed them in a recombinant form (rPagSP04, rPagSP05 and rPagSP06) and tested their applicability in ELISA and immunoblot. One of them, PpSP32-like protein rPagSP06, was identified as the most promising antigen, showing highest resemblance and correlation with the IgG response to P. argentipes salivary gland homogenate. Furthermore, we have validated the applicability of rPagSP06 in a large cohort of 585 individuals and obtained a high correlation coefficient for anti-rPagSP06 and anti-P. argentipes saliva IgG responses. The anti-rPagSP06 and anti-P. argentipes salivary gland homogenate IgG responses followed a similar right-skewed distribution. This is the first report of screening human sera for anti-P. argentipes saliva antibodies using recombinant salivary protein. The rPagSP06 was proven to be a valid antigen for screening human sera for exposure to P. argentipes bites in a visceral leishmaniasis endemic area.

• Keywords
• Bangladesh, IgG antibodies, Leishmania donovani, Marker of exposure, Phlebotomus argentipes, Salivary glands,
• MeSH
• Insect Proteins * immunology   MeSH
• Bites and Stings epidemiology   MeSH
• Leishmania donovani MeSH
• Humans MeSH
• Phlebotomus * MeSH
• Salivary Proteins and Peptides * immunology   MeSH
• Saliva MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Bangladesh epidemiology   MeSH
• Names of Substances
• Insect Proteins * MeSH
• Salivary Proteins and Peptides * MeSH

Phlebotomus perniciosus (Diptera: Phlebotominae) is a medically and veterinary important insect vector. It transmits the unicellular parasite Leishmania infantum that multiplies intracellularly in macrophages causing life-threatening visceral diseases. Leishmania establishment in the vertebrate host is substantially influenced by immunomodulatory properties of vector saliva that are obligatorily co-injected into the feeding site. The repertoire of P. perniciosus salivary molecules has already been revealed and, subsequently, several salivary proteins have been expressed. However, their immunogenic properties have never been studied. In our study, we tested three P. perniciosus recombinant salivary proteins-an apyrase rSP01 and yellow-related proteins rSP03 and rSP03B-and showed their anti-inflammatory nature on the murine bone-marrow derived macrophages. Even in the presence of pro-inflammatory stimuli (IFN-γ and bacterial lipopolysaccharide, LPS), all three recombinant proteins inhibited nitric oxide production. Moreover, rSP03 seems to have a very strong anti-inflammatory effect since it enhanced arginase activity, increased the production of IL-10, and inhibited the production of TNF-α even in macrophages stimulated with IFN-γ and LPS. These results suggest that P. perniciosus apyrase and yellow-related proteins may serve as enhancing factors in sand fly saliva, facilitating the development of Leishmania infection along with their anti-haemostatic properties. Additionally, rSP03 and rSP03B did not elicit the delayed-type hypersensitivity response in mice pre-exposed to P. perniciosus bites (measured as visible skin reaction). The results of our study may help to understand the potential function of recombinant's native counterparts and their role in Leishmania transmission and establishment within the host.

• Keywords
• Phlebotomus, apyrase, immunogenicity, macrophage polarization, sand fly saliva, yellow-related proteins,
• MeSH
• Anti-Inflammatory Agents MeSH
• Phenotype MeSH
• Macrophages MeSH
• Mice MeSH
• Phlebotomus * MeSH
• Dogs MeSH
• Recombinant Proteins MeSH
• Salivary Proteins and Peptides MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Dogs MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Anti-Inflammatory Agents MeSH
• Recombinant Proteins MeSH
• Salivary Proteins and Peptides MeSH

BACKGROUND: In endemic areas of zoonotic leishmaniosis caused by L. infantum, early detection of Leishmania infection in dogs is essential to control the dissemination of the parasite to humans. The aim of this study was to evaluate the serological and/or molecular diagnostic performance of minimally and non-invasive samples (conjunctiva cells (CS) and peripheral blood (PB)) for monitoring Leishmania infection/exposure to Phlebotomus perniciosus salivary antigens in dogs at the beginning and the end of sand fly seasonal activity (May and October, respectively) and to assess associated risks factors. METHODS: A total of 208 sheltered dogs from endemic areas of leishmaniosis were screened. Leishmania DNA detection in PB on filter paper and CS was performed by nested-PCR (nPCR), while the detection of anti-Leishmania antibodies was performed using IFAT and ELISA. The exposure to P. perniciosus salivary antigens (SGH, rSP01 and rSP03B + rSP01) was measured by ELISA. RESULTS: Ninety-seven (46.6%) and 116 (55.8%) of the 208 dogs were positive to Leishmania antibodies or DNA by at least one test at the beginning and end of the sand fly season, respectively. IFAT and ELISA presented a substantial agreement in the serodiagnosis of leishmaniosis. Discrepant PB nPCR results were obtained between sampling points. Leishmania DNA was detected in CS of 72 dogs at the end of the phlebotomine season. The presence of antibodies to the parasite measured by ELISA was significantly higher in dogs presenting clinical signs compatible with leishmaniosis at both sampling points. Phlebotomus perniciosus salivary antibodies were detected in 179 (86.1%) and 198 (95.2%) of the screened dogs at the beginning and end of the phlebotomine season, respectively. CONCLUSIONS: The association between ELISA positivity and clinical signs suggests its usefulness to confirm a clinical suspicion. CS nPCR seems to be an effective and non-invasive method for assessing early exposure to the parasite. PB nPCR should not be used as the sole diagnostic tool to monitor Leishmania infection. The correlation between the levels of antibodies to P. perniciosus saliva and Leishmania antibodies suggests the use of a humoral response to sand fly salivary antigens as biomarkers of L. infantum infection.

• Keywords
• Blood, Conjunctival cells, Dog, Exposure, L. infantum, Phlebotomus pernicious, Saliva,
• MeSH
• Antigens, Protozoan immunology   MeSH
• Endemic Diseases prevention & control   MeSH
• Insect Vectors parasitology   MeSH
• Insect Proteins immunology   MeSH
• Immunoglobulin G blood   MeSH
• Conjunctiva cytology   parasitology   MeSH
• Insect Bites and Stings MeSH
• Leishmania infantum isolation & purification   MeSH
• Leishmaniasis blood   immunology   veterinary   MeSH
• Dog Diseases parasitology   prevention & control   transmission   MeSH
• Phlebotomus parasitology   MeSH
• Antibodies, Protozoan blood   MeSH
• Protozoan Proteins immunology   MeSH
• Dogs MeSH
• Risk Factors MeSH
• Serologic Tests MeSH
• Salivary Proteins and Peptides immunology   MeSH
• Animals MeSH
• Check Tag
• Dogs MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antigens, Protozoan MeSH
• Insect Proteins MeSH
• Immunoglobulin G MeSH
• Antibodies, Protozoan MeSH
• Protozoan Proteins MeSH
• Salivary Proteins and Peptides MeSH

BACKGROUND: Canine leishmaniosis caused by Leishmania infantum is a neglected zoonosis transmitted by sand flies like Phlebotomus perniciosus. Clinical signs and disease susceptibility vary according to various factors, including host immune response and breed. In particular, Ibizan hounds appear more resistant. This immunocompetence could be attributed to a more frequent exposure to uninfected sand flies, eliciting a stronger anti-sand fly saliva antibody response. METHODS: This study aimed to investigate the prevalence of anti-P. perniciosus saliva antibodies in Ibizan hounds and dogs of other breeds in the Leishmania-endemic area of Mallorca, Spain, and to correlate these antibody levels with clinical, immunological and parasitological parameters. Anti-sand fly saliva IgG was examined in 47 Ibizan hounds and 45 dogs of other breeds using three methods: P. perniciosus whole salivary gland homogenate (SGH) ELISA; recombinant protein rSP03B ELISA; and rSP03B rapid tests (RT). Additionally, diagnostic performance was evaluated between methods. RESULTS: Results indicate significantly higher anti-SGH antibodies (P = 0.0061) and a trend for more positive SGH ELISA and RT results in Ibizan hounds compared to other breeds. General linear model analysis also found breed to be a significant factor in SGH ELISA units and a marginally significant factor in RT result. Although infection rates were similar between groups, Ibizan hounds included significantly more IFN-γ producers (P = 0.0122) and papular dermatitis cases (P < 0.0001). Older age and L. infantum seropositivity were also considered significant factors in sand fly saliva antibody levels according to at least one test. Fair agreement was found between all three tests, with the highest value between SGH and rSP03B RT. CONCLUSIONS: To our knowledge, this is the first study elaborating the relationship between anti-P. perniciosus saliva antibodies and extensive clinical data in dogs in an endemic area. Our results suggest that Ibizan hounds experience a higher frequency of exposure to sand flies and have a stronger cellular immune response to L. infantum infection than other breed dogs. Additional sampling is needed to confirm results, but anti-P. perniciosus saliva antibodies appear to negatively correlate with susceptibility to L. infantum infection and could possibly contribute to the resistance observed in Ibizan hounds.

• Keywords
• Anti-sand fly saliva antibodies, Canine leishmaniosis, Ibizan hounds, Leishmania infantum, Papular dermatitis, Phlebotomus perniciosus, rSP03B,
• MeSH
• Breeding MeSH
• Endemic Diseases MeSH
• Insect Proteins immunology   MeSH
• Immunoglobulin G immunology   MeSH
• Leishmaniasis immunology   veterinary   MeSH
• Disease Susceptibility MeSH
• Dog Diseases immunology   parasitology   MeSH
• Phlebotomus immunology   MeSH
• Dogs MeSH
• Salivary Proteins and Peptides immunology   MeSH
• Saliva immunology   MeSH
• Zoonoses parasitology   transmission   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Dogs MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Spain MeSH
• Names of Substances
• Insect Proteins MeSH
• Immunoglobulin G MeSH
• Salivary Proteins and Peptides MeSH

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: Zoonotic leishmaniosis, caused by the protozoan Leishmania infantum, is a public and animal health problem in Asia, Central and South America, the Middle East and the Mediterranean Basin. Several phlebotomine sand fly species from the subgenus Larroussius are vectors of L. infantum. Data from dogs living in endemic areas of leishmaniosis advocate the use of antibody response to phlebotomine sand fly saliva as an epidemiological biomarker for monitoring vector exposure. The aim of this study was to analyse the exposure of cats to phlebotomine sand flies using detection of IgG antibodies to Phlebotomus perniciosus saliva. The association between phlebotomine sand fly exposure and the presence of Leishmania infection was also investigated. RESULTS: IgG antibodies to P. perniciosus saliva were detected in 167 (47.7%) out of 350 cats; higher antibody levels were present in sera collected during the period of phlebotomine sand fly seasonal activity (OR = 19.44, 95% CI: 9.84-38.41). Cats of 12-35 months had higher antibody levels than younger ones (OR = 3.56, 95% CI: 1.39-9.16); this difference was also significant with older cats (for 36-95 months-old, OR = 9.43, 95% CI: 3.62-24.48; for older than 95 months, OR = 9.68, 95% CI: 3.92-23.91). Leishmania spp. DNA was detected in the blood of 24 (6.9%) cats, while antibodies to L. infantum were detected in three (0.9%). Only one cat was positive to Leishmania by both techniques. Cats presenting IgG antibodies to P. perniciosus had a significantly higher risk of being positive for Leishmania infection. CONCLUSIONS: To our knowledge, this is the first study demonstrating anti-sand fly saliva antibodies in cats. The evaluation of the contact of this animal species with the vector is important to the development of prophylactic measures directed to cats, with the aim of reducing the prevalence of infection in an endemic area. Therefore, studies evaluating whether the use of imidacloprid/flumethrin collars reduces the frequency of P. perniciosus bites in cats are needed. It is also important to evaluate if there is a correlation between the number of phlebotomine sand fly bites and IgG antibody levels.

• Keywords
• Antibodies, Cat, Leishmania infantum, Phlebotomus perniciosus, Portugal, Saliva,
• MeSH
• Immunoglobulin G immunology   MeSH
• Cats MeSH
• Leishmania infantum immunology   MeSH
• Leishmaniasis, Visceral veterinary   MeSH
• Cat Diseases immunology   parasitology   MeSH
• Phlebotomus immunology   MeSH
• Risk Factors MeSH
• Saliva immunology   MeSH
• Antibody Formation MeSH
• Animals MeSH
• Check Tag
• Cats MeSH
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Immunoglobulin G 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