Predição de alvos quimioterápicos e design de vacina multi-epítopo em Corynebacterium ulcerans e C. silvaticum

Abstract

Corynebacterium is a genus of gram-positive bacteria that contains species of medical, veterinary and biotechnological importance. Among the pathogenic bacteria there is a clade containing six species that can be lysed by corynephages tox+ and produce diphtheria toxin (DT), called the C. diphtheriae complex. Among the species of the complex, C. ulcerans is a zoonotic bacterium that infects several mammals and can cause different diseases. Currently DT-producing strains are the major cause of diphtheria, which is increasing in underdeveloped countries due to neglected vaccination. Vaccinated people can become infected and transmit the pathogen. In addition, the vaccine does not protect against non-DT-producing strains, which are capable of causing other diseases. C. silvaticum is a recently described species of veterinary importance that causes caseous lymphadenitis in pigs and roe deer, and has zoonotic potential. Little is known about its geographic distribution and host spectrum. In this context, the development of a new vaccine capable of protecting against DT-producing and non-DT- producing strains of the two species would have medium and veterinary relevance. In addition, for cases of infection treatment, the identification of new chemotherapeutics would be an alternative in case of resistance to the current ones. In this work we use in silico strategies to identify, for the two species, new chemotherapeutic target proteins and to develop new vaccines. The 72 C. ulcerans and 36 C. silvaticum genomes were analyzed. By means of subtractive genomics it was possible to identify four target proteins of chemotherapeutic agents. Using molecular docking and a library of 5,008 natural compounds, three possible chemotherapeutics were identified for each of the target proteins. Through reverse vaccinology, nine probable target proteins were identified. An immunoinformatic analysis was performed to design multi-epitope vaccines from 25 epitopes in common among eight of the nine previously identified proteins. Four multi-epitope vaccines were designed with different adjuvants, capable of inducing innate and adaptive immune responses. The information generated could reduce the cost and time for the discovery of new antibiotics and for the development of a vaccine for bothspecies, capable of protecting against non-DT-producing strains.