Immunogenic Peptides from Pap31 and SCS-α of Bartonella bacilliformis: One Step Closer to a Rapid Diagnostic Tool for Carrion's Disease.

Cláudia Gomes,Maria J Pons,Juana Del Valle-Mendoza,Mayumi Matsuoka,Joaquim Ruiz

doi:10.3390/pathogens10080917

Abstract

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.

Highlights

Bartonella bacilliformis is the microorganism responsible for Carrion’s disease, an overlooked illness restricted to the Andean region of Peru, Ecuador, and Colombia [1]
After cloning the complete proteins of Pap31 and succinyl-CoA synthetase α (SCS-α) and their respective truncated constructs (Pap31–A, Pap31–B, Pap31–C, SCS α–A, SCS α–B and SCS α–C), we performed Western blotting showing that the immunogenic region of Pap31 antigen is contained in clones B and C, and for SCS-α, the immunogenic region is in clone A (Figure 1)
Two different analyses were performed to establish which peptides could be the best candidates for use in a future diagnostic test

Summary

Introduction

Bartonella bacilliformis is the microorganism responsible for Carrion’s disease, an overlooked illness restricted to the Andean region of Peru, Ecuador, and Colombia [1]. This illness is transmitted by the bite of a sandfly, predominantly Lutzomyia verrucarum, and up to now, humans are the only established reservoir [1]. In the chronic phase, B. bacilliformis produces an abnormal proliferation of endothelial cells causing characteristic dermal eruptions named Peruvian warts [1]. In this phase, mortality is considered irrelevant [1]. Studies using more sensitive techniques, such as real-time PCR, detected approximately 40% of asymptomatic carriers in post-outbreak and endemic areas [5]

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