Identification through phage display with cDNAs synthetic library of antigenic epitopes of Schistosoma mansoni targeted by the immune response of Rhesus monkeys (Macaca mulatta) infected by the parasite and self-cured

Abstract

Schistosomiasis is currently considered the second leading Neglected Tropical Disease (NTD), and is present in 78 countries. It is estimated that around 54 million people are infected with the species Schistosoma mansoni and 393 million living in an area of risk, with praziquantel being the only drug available for the treatment of this parasite. The present research project aims to identify parasite proteins that are the targets of the immune response of S. mansoni infected Rhesus monkeys, since in these animals the course of infection starts normally, and after a few weeks the monkeys are able to self-heal and develop a strong resistance to a second challenge. We will use a synthetic library of oligos (cDNAs) that encodes all proteins known of the parasite. For the oligos library, fragments of all ORFs will be synthesized by releasable DNA microarray technique, totaling approximately 120,000 sequences covering 13,000 genes encoding parasite proteins. Protein fragments encoded by these oligos will be expressed as fusion proteins in the bacteriophage PG8.2 viral capsid by the phage display technique and unbiased screening of antigenic epitopes will be performed by exposing the phage library to the antibodies present in the collected plasma along the infection and reinfection (challenge) of each of 12 infected and self-cured Rhesus monkeys. Phage bound to the plasma antibodies will be immunoprecipitated and their cDNA inserts will be sequenced by the PhIP-Seq technique. The results of the sequencing will be analyzed by bioinformatics tools and correlated with the process of self-healing and resistance to challenge, with the intention of discovering new vaccine candidate targets for Schistosomiasis. (AU)