Identificação de moléculas reativas com anticorpos associados a dengue

Abstract

Dengue fever is an arboviral infection highly common in Brazil, and it corresponds to a major public health problem. Annually, its incidence overcomes 50,000,000, from which about 25,000 are associated to death cases. Due to this high incidence and number of death, it is of great urgency to identify this disease while in an early state. That way, would be possible to avoid any progression of the disease to more severe cases. A major problem related to dengue is that the virus is represented by four subtypes, which are phylogenetically distinct (DENV1, DENV2, DENV3 and DENV4). This means that, although the manifestations and the forms of dissemination are the same, an infection caused by one of the serotypes will not protect against the others. In fact, an infection caused by one of the four serotypes may intensify even more the disease caused by a secondary infection by the three others. One hypothesis that could explain this relationship between heterotypic infections and severe cases of the disease is the ADE hypothesis (antibody-dependent enhancement), which suggests that a secondary infection would cause a cross-reaction between antigen and antibody, preventing the virus of being inactivated. As a consequence, it would result in an increase of the production of inflammatory mediators and vascular permeability that would intensify the disease. Therefore, it’s very important to identify the disease while it is still in an initial stage. However, this early identification is hard and its diagnosis is still limited. Thus, a serological marker would be highly valuable. Recently, serological biomarkers for early diagnosis have become a topic of great interest. These biomarkers have advantages of not being invasive to the patient and inexpensive to produce and analyze. Thus, in this project, we introduce a new technology for the search of such markers, the peptoids. Peptoids are synthetic oligomers, composed of N-substituted glycine units, and can be used for several biological utilities that provide an alternative technology for the investigation and the elucidation of the immune response. Moreover, they have been used and reported as a potential candidate for the search of serological biomarkers due to their chemical stability in fluids where degradative enzymes can be found. In addition to that, the fact that there is no need for a prior knowledge about the target only make them even more attractive for such “job”. In this project, a combinatorial library of about one million of peptoids was screened in sera from dengue positive patients, as well as negative patients. Hereby we report the potential of this synthetic molecules for the identification of antibodies with clinical relevance present in the patients' serum. The results here reported were generated by 3 consecutive screening steps, where 33 reactive peptoids were identified as potential biomarkers. Because of the impartiality of this technique, we believe that at least one of these 33 peptoids are extremely specific for the studied disease. Currently, they have been sent for the sequencing and re-synthesis step, so that new experiments can be done and the study can continue. We are very excited and we don’t expect nothing less than promising results in the field of diagnosis and dengue.