Monitoring Leishmania infection and exposure to Phlebotomus perniciosus using minimal and non-invasive canine samples

Abstract

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.

Leishmania exposure in dogs from two endemic countries from New and Old Worlds (Brazil and Portugal): evaluation of three serological tests using Bayesian Latent Class Models

“…The estimated posterior median of Leishmania seroprevalence of 13.4% obtained with both models in the dogs from Portugal was similar to the percentage obtained with the total number of canine sera tested with L. infantum IgG-ELISA ® , i.e. 12.5% and 13.9% at the beginning and end of the sand fly season, respectively [ 23 ]. The three techniques used in this study were found to be specific for the detection of antibodies against Leishmania in the Portuguese population of dogs, with specificity values between 92.5 and 99.1%.…”

“…Serum samples from a total of 378 dogs (194 from Portugal and 184 from Brazil) obtained in previous epidemiological studies [ 16 , 23 ] were analyzed. Portuguese dogs were from four private kennels of the Metropolitan Lisbon region, and domiciled Brazilian dogs were from the municipality of Camaçari, located in the State of Bahia.…”

“…Bayesian approach may combine information from the collected data and prior information about the parameters. Prior information on the prevalence of infection within each subpopulation was considered from a Uniform distribution in [0, 0.30], based on previous studies [ 16 , 23 ]. Initially, uniform distributions in [0, 1] were used to express non-informative information for the test accuracy (sensitivity and specificity of the tests across populations).…”

PpSP32-like protein as a marker of human exposure to Phlebotomus argentipes in Leishmania donovani foci in Bangladesh

“…These results are somewhat surprising as yellow-related, and antigen 5-related proteins are known as suitable exposure markers in other sand fly species. Yellow-related proteins were demonstrated as valid markers of human exposure to Lutzomyia longipalpis ( Souza et al, 2010 ) and Phlebotomus orientalis ( Sumova et al, 2018 ) and repeatedly of canine exposure to Phlebotomus perniciosus ( Martín-Martín et al, 2014 , Kostalova et al, 2015 , Kostalova et al, 2017 , Risueño et al, 2018 , Willen et al, 2019 , Maia et al, 2020 ). Antigen 5-related proteins were proposed as human exposure markers to Lutzomyia intermedia ( Carvalho et al, 2017 ) and P. orientalis ( Sumova et al, 2018 ).…”

Phlebotomus perniciosus Recombinant Salivary Proteins Polarize Murine Macrophages Toward the Anti-Inflammatory Phenotype

“…The complexity of sand fly salivary proteins has already been revealed for several sand fly species (Coutinho-Abreu and Valenzuela, 2018 ; Oliveira et al, 2020 ; Polanska et al, 2020 ), including P. perniciosus (Anderson et al, 2006 ; Martin-Martin et al, 2013 ). Several salivary proteins from this sand fly species have been expressed and further tested primarily as markers of exposure (Lestinova et al, 2017 ; Velez et al, 2018 ; Willen et al, 2018 , 2019 ; Risueno et al, 2019 ; Burnham et al, 2020 ; Maia et al, 2020 ). However, the functional studies of P. perniciosus salivary recombinant proteins are very limited (Sumova et al, 2019 ), and so far there is no study on their immunomodulatory properties.…”