Search Results (3)

Carrion’s disease, caused by infection with the bacterium Bartonella bacilliformis (B. bacilliformis), is effectively treated with antibiotics, but reaches fatality rates of ~90% if untreated. Current diagnostic methods are limited, insufficiently sensitive, or require laboratory technology unavailable in endemic areas. Electrochemical aptamer-based (E-AB) biosensors provide a potential solution for this unmet need, as these biosensors are portable, sensitive, and can rapidly report the detection of small molecule targets. Here, we developed an E-AB biosensor to detect Pap31, a biomarker of Carrion’s disease and an outer membrane protein in B. bacilliformis. We identified an aptamer with Pap31-specific binding affinity using a magnetic pull-down assay with magnetic bead-bound Pap31 and an aptamer library followed by electrophoretic mobility shift assays. We incorporated the Pap31-binding aptamer into a DNA oligonucleotide that changes conformation upon binding Pap31. The resultant Pap31 E-AB biosensor produced a rapid, significant, and target-specific electrical current readout in the buffer, demonstrating an apparent K_D of 0.95 nM with a limit of detection of 0.1 nM, and no significant signal change when challenged with off-target proteins. This proof-of-concept Pap31 biosensor design is a first step toward the development of more rapid, sensitive, and portable diagnostic tools for detecting Carrion’s disease. Full article

Carrion’s disease, caused by Bartonella bacilliformis, is a neglected tropical disease prevalent in the Andean region of South America. Without antimicrobial treatment, this disease has a mortality rate of up to 88% in infected patients. The most common method for diagnosing B. bacilliformis infection is serological testing. However, the current serological assays are limited in sensitivity and specificity, underscoring the need for the development of novel and more accurate diagnostic tools. Recombinant proteins have emerged as promising candidates to improve the serological diagnosis of Carrion’s disease. So, we focused on evaluating the conditions for producing two previously predicted proteins of B. bacilliformis using the baculovirus–insect cell expression system, mainly the flashBAC ULTRA technology. We assessed various parameters to identify the conditions that yield the highest protein production, including cell lines, temperature, and hours post-infection (hpi). The results showed that the expression conditions for achieving the highest yields of the Prot_689 and Prot_504 proteins were obtained using High Five™ cells at 21 °C and harvesting at 120 hpi. Subsequently, the seroreactivity of recombinant proteins was evaluated using positive sera from patients diagnosed with Carrion’s disease. These findings offer valuable insights into the production conditions of B. bacilliformis recombinant proteins using the baculovirus system, which could significantly contribute to developing more precise diagnostic tools for Carrion’s disease. Therefore, this research provides implications for improving diagnostics and potentially developing therapeutic strategies. Full article

Bartonella bacilliformis is the causal agent of Carrion’s disease, an overlooked illness endemic in the Andean Mountains with Peru being the most affected country. The diagnostic of this illness is a challenge due to the limited resources and the common symptomatology with other infectious diseases. The goal of this study was to identify immunogenic peptides from Pap31 and succinyl-CoA synthetase α (SCS-α) of B. bacilliformis that might be suitable for developing a serologic tool. The immunodominant character of Pap31 and SCS-α was determined by Western blotting and in-silico analysis. Subsequently, 35 peptides were selected for epitope mapping and their immunoreactivity was tested by enzyme-linked immunosorbent assay (ELISA). A total of 30 sera were tested including pre-exposed people with high IgM levels for Pap31/SCS-α (23 sera), patients (2 sera) as well as 5 sera with no reactivity to Pap31/SCS-α. The results indicate that Pap31-8 (₁₈₇QAIGSAILKGTKDTGT₂₀₂) and SCS-α-12 (₅₉IFASVAEGKEKTGANA₇₄) are the most immunogenic peptides, with Pap31-8 showing potential to discriminate between B. bacilliformis and the remaining Bartonella spp., and SCS-α-12 differentiating Bartonella spp. from other microorganisms. Full article