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whole salivary gland homogenate as an antigen to detect these antibodies has several limitations, therefore it is being superseded by the use of specific recombinant salivary proteins.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