Browsing by Author "Jin, Yipeng"

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    Rapid and reliable detection of Leishmania antibodies in canine serum with double-antigen sandwich homogeneous chemical luminescence
    (2024-07-30) Zhao, Xiangjun; Ma, Licai; Jin, Yipeng; Barkema, Herman W.; Kastelic, John P.; Wang, Lu; Wen, Kai; Liu, Gang
    Abstract Background Leishmaniasis, caused by Leishmania spp. parasites, is an important zoonotic disease globally, posing severe threats to humans and animals. In the absence of effective vaccines, reliable serological diagnostic methods are critical for disease control. However, the enzyme-linked immunosorbent assay (ELISA) and immunochromatographic assay have limitations due to complexity, time required and/or sensitivity. Therefore, our objective was to develop an accurate, rapid and user-friendly detection method of canine leishmania antibody based on double-antigen sandwich homogeneous chemical luminescence. Methods Homogeneous chemiluminescent technology was employed, and expressed recombinant fusion proteins containing full-length K9, K39 and K26 repeat sequences were used as diagnostic antigens. To establish a dual-antigen sandwich serological assay capable of detecting various antibody types, a factorial design was used to optimize concentrations of diagnostic antigen-receptor microspheres and of biotinylated diagnostic antigens, as well as of reaction solution composition and reaction duration. To evaluate and validate this newly developed method, we collected 41 Leishmania-positive serum samples, 30 Leishmania-negative control serum samples and 78 clinical serum samples for which no diagnostic information was available. Comparative analyses were performed using parasitological testing and an indirect ELISA as reference methods, focusing on diagnostic sensitivity and specificity. Results Sodium dodecyl sulfate–polyacrylamide gel electrophoresis confirmed the purification of the diagnostic antigens, which exhibited clear bands without impurities. Based on results from the 41 Leishmania-positive samples and 30 Leishmania-negative samples, there was sufficient sensitivity to detect samples diluted up to 256-fold, with analytical specificity of 100%. Overall diagnostic sensitivity was 100% and diagnostic specificity was 93.3%. Diagnostic performance was highly consistent between the newly developed method and the indirect ELISA (Kappa = 0.82, P < 0.01). Testing could be completed within 35 min with the new method Conclusions We have developed a novel double-antigen sandwich homogeneous chemical luminescence method to detect canine Leishmania antibodies, with high sensitively and specificity, a short incubation interval and a simple protocol. This streamlined approach not only offers a sensitive and efficient method for clinical diagnosis but also has great potential for use in automated testing. Graphical Abstract
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    Re-emergence of canine Leishmania infantum infection in mountain areas of Beijing
    (2023-03-30) Liu, Gang; Wu, Yuanheng; Wang, Lei; Liu, Yang; Huang, Wei; Li, Yifan; Gao, Mengbo; Kastelic, John; Barkema, Herman W.; Xia, Zhaofei; Jin, Yipeng
    Abstract Canine Leishmaniasis (CanL) is an endemic infectious disease in China, causing visceral Leishmaniasis (VL) and resulting in important public health problem. However, in the last 3 y, endemic trends have changed considerably and spatial–temporal aggregation areas have shifted from northwestern to central China. Although Beijing was an endemic area for CanL in the last century, this disease has not been reported in Beijing since control programs were implemented in the 1950s. In the present study, PCR and immunochromatographic (ICT) were used to estimate prevalence of Leishmania infection in domestic dogs living in Beijing, a VL re -emergencearea. In total, 4420 canine blood samples were collected at vet clinics in 14 districts of Beijing. Overall prevalence (percentage of dogs seropositive and/or PCR positive) of CanL infection in Beijing was 1.22% (54/4420). However, prevalence of CanL in the western mountain areas was 4.68% (45/961), significantly higher than that (0.26%, 9/3459) of the plains. In addition, multilocus sequence typing (MLST) of seven enzyme-coding genes was used to examine phylogenetic relationships of CanL strains. Forty-one Leishmania infantum isolates were well separated from the other strains and divided into five major clades (A to E) by MLST analysis. All clades were closely related to strains from Sichuan Province and Gansu Province. A phylogenetic tree, based on the MLST, revealed that L. infantum in Beijing was genetically related to strains from western endemic of Mountain type VL in China. In conclusion, CanL has re-emerged in Beijing, and almost 5% of dogs living in Beijing’s mountain areas were infected with L. infantum. The phylogenetic tree based on MLST effectively distinguished species of Leishmania and reflected geographical origins. Because dogs are considered a natural reservoir, comprehensive control measures including surveillance, phylogenetic analyses and management should be implemented to mitigate or eliminate Leishmaniasis.