Plasmonic rK28 ELISA improves the diagnosis of canine Leishmania infection

Development of a Gold Nanoparticle-Based ELISA for Detection of PCV2

In this new methodology, plasmonic ELISA (pELISA) was used to detect Circovirus porcine2 (PCV2) in serum samples without the need for plate reading equipment. This process occurs by adapting the conventional ELISA test with gold nanoparticles (AuNPs) to promote a color change on the plate and quickly identify this difference with the naked eye, generating a dark purple-gray hue when the samples are positive and red when the samples are negative. The technique demonstrated high efficiency in detecting samples with a viral load ≥ 5 log10 copies/mL. Plasmonic ELISA offers user-friendly, cost-effective, and reliable characteristics, making it a valuable tool for PCV2 diagnosis and potentially adaptable for other pathogen detection applications.

Antigens and their diagnostic performance for Canine Visceral Leishmaniasis: A critical review

Canine visceral leishmaniasis (CVL) is the most aggressive and lethal form of leishmaniasis manifesting in dogs and represents a major public health concern. Although there are sufficiently sensitive molecular tools for CVL diagnosis, they are not accessible at the main points of disease dissemination, in which context serodiagnosis has been used as an alternative tool on the epidemiological control. As an attempt to develop more accurate immunodiagnostic assays, many antigens have been tested over the years, on different platforms. This review aimed to access studies reporting new antigens that can be applied for CVL serodiagnosis. Articles published from January of 2016 to March of 2021 were retrieved from Google Scholar, Science Direct, and PubMed, using "Canine Visceral Leishmaniasis" and "Serodiagnosis" as keywords. In total, 1527 articles were identified, of which 42 were selected based on exclusion factors. Sensitivity, specificity, sample size, and sample quality data were extracted by manual curation and analyzed. Of the selected articles, 26 contemplated ELISA, which enabled a more thorough comparison and a critical review of these studies. Soluble Leishmania Antigens (SLA) and the A2 protein were used as controls in 53.8 and 46.15 % of these articles, respectively, and were evaluated separately; their frequent use was questioned. Subsequently, articles that evaluated other assay platforms, such as immunochromatography, immunosensors, and others, were also reported and evaluated. Finally, data relative to validation studies of commercial kits were briefly discussed. Our results show that there are several antigens with great potential for the development of accurate diagnostic tools, but further testing is required. The critical analysis also brings insights that can be useful for more assertive diagnostic development of more robust tools for CVL serodiagnosis.

Revisiting the heterogeneous global genomic population structure of Leishmania infantum

Leishmania infantum is the main causative agent responsible for visceral leishmaniasis (VL), a disease with global distribution. The genomic structure and genetic variation of this species have been widely studied in different parts of the world. However, in some countries, this information is still yet unknown, as is the genomic behaviour of the main antigens used in VL diagnosis (rK39 and rK28), which have demonstrated variable sensitivity and specificity in a manner dependent on the geographic region analysed. The objective of this study was to explore the genomic architecture and diversity of four Colombian L. infantum isolates obtained in this study and to compare these results with the genetic analysis of 183 L. infantum isolates from across the world (obtained from public databases), as well as to analyse the whole rK39 and rK28 antigen sequences in our dataset. The results showed that, at the global level, L. infantum has high genetic homogeneity and extensive aneuploidy. Furthermore, we demonstrated that there are distinct populations of L. infantum circulating in various countries throughout the globe and that populations of distant countries have close genomic relationships. Additionally, this study demonstrated the high genetic variability of the rK28 antigen worldwide. In conclusion, our study allowed us to (i) expand our knowledge of the genomic structure of global L. infantum; (ii) describe the intra-specific genomic variability of this species; and (iii) understand the genomic characteristics of the main antigens used in the diagnosis of VL. Additionally, this is the first study to report whole-genome sequences of Colombian L. infantum isolates.

Determination of cardiac disease biomarker by plasmonic sandwich ELISA

Acute myocardial infarction (AMI) is the heart attack happening when the blood flow is terminated to the heart muscles. C-reactive protein (CRP) level is raising significantly in AMI patients after the onset of symptom; also, temporal variations of CRP in plasma of AMI patient have also been found. Quantifying the concentration of CRP helps to identify the condition associated with AMI. Plasmonic enzyme-linked immunosorbent assay (ELISA) was utilized here to identify CRP by the sandwich of aptamer and antibody. Bare-eye CRP detection was achieved by plasmonic ELISA through the aggregation (blue color) of gold nanoparticle in the presence of CRP, whereas in the absence of CRP, it retains its red color (dispersion). Depending on the catalase presence on the ELISA surface, hydrogen peroxide (H₂ O₂ ) controls gold growth and differentiates with color changes. To achieve the lowest detection limit of CRP, H₂ O₂ (200 µM), gold seed (0.2 µM), and streptavidin-catalase (1:500) were found optimal. The detection limit was reached at 0.25 µg/mL, whereas it was 0.5 µg/mL in the CRP-spiked serum. This method of detection system is easier to detect the levels of CRP and helps diagnosing AMI.