Multiplex flow cytometry serology to diagnosis of canine visceral leishmaniasis

Synthetic Peptides Selected by Immunoinformatics as Potential Tools for the Specific Diagnosis of Canine Visceral Leishmaniasis

Diagnosing canine visceral leishmaniasis (CVL) in Brazil faces challenges due to the limitations regarding the sensitivity and specificity of the current diagnostic protocol. Therefore, it is urgent to map new antigens or enhance the existing ones for future diagnostic techniques. Immunoinformatic tools are promising in the identification of new potential epitopes or antigen candidates. In this study, we evaluated peptides selected by epitope prediction for CVL serodiagnosis in ELISA assays. Ten B-cell epitopes were immunogenic in silico, but two peptides (peptides No. 45 and No. 48) showed the best performance in vitro. The selected peptides, both individually and in combination, were highly diagnostically accurate, with sensitivities ranging from 86.4% to 100% and with a specificity of approximately 90%. We observed that the combination of peptides showed better performance when compared to peptide alone, by detecting all asymptomatic dogs, showing lower cross-reactivity in sera from dogs with other canine infections, and did not detect vaccinated animals. Moreover, our data indicate the potential use of immunoinformatic tools associated with ELISA assays for the selection and evaluation of potential new targets, such as peptides, applied to the diagnosis of CVL.

The recent advances of cancer associated fibroblasts in cancer progression and therapy

As an abundant component of tumor microenvironment, cancer-associated fibroblasts (CAFs) are heterogeneous cell populations that play important roles in tumor development, progression and therapeutic resistance. Multiple sources of cells can be recruited and educated to become CAFs, such as fibroblasts, mesenchymal stem cells and adipocytes, which may explain the phenotypic and functional heterogeneity of CAFs. It is widely believed that CAFs regulate tumor progression by remodeling extracellular matrix, promoting angiogenesis, and releasing soluble cytokines, making them a promising cancer therapy target. In this review, we discussed about the origin, subpopulation, and functional heterogeneity of CAFs, with particular attention to recent research advances and clinical therapeutic potential of CAFs in cancer.

Antigenic diversity of MASP gene family of Trypanosoma cruzi

Trypanosoma cruzi, the etiological agent of Chagas disease (CD), is a heterogeneous species with high genetic and phenotypic diversity. MASP is the second largest multigene family of T. cruzi. The high degree of polymorphism of the family associated with its location at the surface of infective forms of T. cruzi suggests that MASP participates in mechanisms of host-parasite interaction. In this work, MASP members were divided into 7 subgroups based on protein sequence similarity, and one representative member from each subgroup was chosen to be expressed recombinantly. Immunogenicity of recombinant MASP proteins (rMASP) was investigated using different sera panels from T. cruzi infected mice. To mimic a natural condition in which different MASP members are expressed at the same time in the parasite population, a multiplex bead-based flow cytometry assay was also standardized. Results showed that rMASPs are poorly recognized by sera from mice infected with Colombiana strain, whereas sera from mice infected with CL Brener and Y display high reactivity against the majority of rMASPs tested. Flow cytometry showed that MASP recognition profile changes 10 days after infection. Also, multiplex assay suggests that MASP M1 and M2 are more immunogenic than the other MASP members evaluated that may play an immunodominant role during infection.

A Flow Cytometry-Based Serological Assay to Detect Visceral Leishmaniasis in HIV-Infected Patients

Visceral Leishmaniasis (VL) is a severe parasitic disease that has emerged as an important opportunistic condition in HIV-infected patients and whose control is impaired by inaccurate identification. This is mainly due to the serological tests used for VL having a reduced performance in cases of VL-HIV coinfection due to a low humoral response. In this situation, however, a positive test has even greater diagnostic value when combined with the clinical status. This study aimed to evaluate the application and performance of flow cytometry to detect anti-Leishmania infantum antibodies in HIV-infected patients. Sera from VL/HIV coinfected patients, characterized using "gold standard" techniques, were compared with sera from healthy controls plus sera from HIV-infected individuals. The flow cytometry results were expressed as levels of IgG reactivity, based on the percentage of positive fluorescent parasites (PPFP). A ROC curve analysis of a serum titration indicated a PPFP of 1.26% as being the cutoff point to segregate positive and negative results. At the 1:2,048 dilution, with 89% sensitivity and 83% specificity, flow cytometry showed greater sensitivity in relation to the serological tests evaluated. Futhermore, flow cytometry was the only assay that positively identified all VL-HIV patients with quantified HIV load. Together, these findings suggest that flow cytometry may be used as an alternative serological approach for VL identification and as a tool to characterize the humoral response against Leishmania infantum in HIV-infected patients.

Impedimetric immunosensor for rapid and simultaneous detection of chagas and visceral leishmaniasis for point of care diagnosis

In this work, a dual detection system based on an impedimetric immunosensor was developed for the first time for the simultaneous detection of anti-Trypanosoma cruzi and anti-Leishmania infantum antibodies in human and dog serum samples. The IBMP 8.1 and rLci1A/rLci2B recombinant antigens were immobilized over the surface of dual screen-printed carbon electrodes (W1 and W2) modified with poly (4-hydroxyphenylacetic acid). Under optimized conditions, the immunosensor recognized specific interactions for anti-T. cruzi antibodies up to a dilution of 1:10,240 and for anti-L. infantum up to 1:5120 in canine serum samples. Relative standard deviation (RSD) values of 2.8% for W1 and 3.6% for W2 were obtained for T. cruzi (W1) and L. infantum antigen (W2) samples in three different electrodes for 3 days (n = 9). The immunosensor was stored at 4 °C for 8 weeks, with activity retention of 70.2% in W1 and 78.2% in W2. The results using the recombinant proteins revealed that all antigens discriminated between negative and positive samples (p < 0.0001) in both dog and human groups, as well as no cross-reactivity could be detected among sera with other infections. With this approach, immunosensor-based diagnostic tests achieved 100% accuracy, suggesting that the antigens are eligible to enter Phase-II studies.

Recent advances and new strategies in Leishmaniasis diagnosis

Leishmaniasis is a set of complex and multifaceted syndromes, with different clinical manifestations, caused by different species of the genus Leishmania spp. that can be characterized by at least four syndromes: visceral leishmaniasis (VL, also known as kala-azar), post-kala-azar dermal leishmaniasis (PKDL), cutaneous leishmaniasis (CL), and mucocutaneous leishmaniasis (MCL). Among the most serious clinical forms, VL stands out, which causes the death of around 59,000 people annually. Fast and accurate diagnosis in VL is essential to reduce the disease's morbidity and mortality. There are a large number of diagnostic tests for leishmaniasis, however they do cross-react with other protozoa and their sensitivity changes according to the clinical form of the disease. Thus, it is essential and necessary to provide a diagnosis that is sufficiently sensitive to detect asymptomatic infected individuals and specific to discriminate individuals with other infectious and parasitic diseases, thus enabling more accurate diagnostic tools than those currently used. In this context, the aim of this review is to summarize the conventional diagnostic tools and point out the new advances and strategies on visceral and cutaneous leishmaniasis diagnosis.

Biotechnological applications from a Leishmania amastigote-specific hypothetical protein in the canine and human visceral leishmaniasis

The treatment against visceral leishmaniasis (VL) presents problems, mainly related to the toxicity and/or high cost of the drugs. In this context, a rapid and precise diagnosis of the disease should be performed, mainly to treat patients as soon as possible, aiming to reduce the treatment time and the toxicity of the therapeutics. In the present study, the diagnostic role of an amastigote-specific Leishmania protein was evaluated in the canine and human VL. Results showed that the recombinant protein (called rLiHyJ) and one specific B cell epitope (called PeptJ) predicted from protein sequence presented high sensitivity and specificity values to diagnose canine and human disease, showing also a low reactivity against cross-reactive samples. The rA2 protein and a parasite antigenic extract showed variable sensitivity and/or specificity values in the ELISA experiments. A prognostic evaluation of protein and peptide in the human VL indicated that specific IgG antibodies significantly decreased after treatment, when compared to be values obtained before therapy. The in vitro immunogenicity using rLiHyJ in peripheral blood mononuclear cell (PBMC) cultures collected of such patients and healthy subjects suggested that the protein induced lymphoproliferation and high IFN-γ production in the stimulated cells. In conclusion, although preliminary, results suggest that rLiHyJ and PeptJ could present distinct biotechnological applications in the canine and human VL.