Pan-genomic analyses of 47 complete genomes of the Rickettsia genus and prediction of new vaccine targets and virulence factors of the species

Abstract

The genus Rickettsia belongs to the Proteobacteria phylum and these bacteria infect animals and humans causing a range of diseases worldwide. The genus is divided into 4 groups and despite the public health threat and the knowledge accumulated so far, the mandatory intracellular bacteria behaviour and limitation for in vitro culture makes it difficult to create new vaccines and drug targets to these bacteria. In an attempt to overcome these limitations, pan-genomic approaches has used 47 genomes of the genus Rickettsia, in order to describe species similarities and genomics islands. Moreover, we conducted reverse vaccinology and docking analysis aiming the identification of proteins that have great potential to become vaccine and drug targets. We found out that the bacteria of the four Rickettsia groups have a high similarity with each other, with about 90 to 100% of identity. A pathogenicity island and a resistance island were predicted. In addition, 8 proteins were also predicted as strong candidates for vaccine and 9 as candidates for drug targets. The prediction of the proteins leads us to believe in a possibility of prospecting potential drugs or creating a polyvalent vaccine, which could reach most strains of this large group of bacteria.

Communicated by Ramaswamy H. Sarma

Keywords:

• Rickettsia
• Pan-genomics
• reverse vaccinology
• pathogenicity islands
• drug targets

Disclosure statement

We declare we have no competing interests.

Data accessibility

The genomes are available at GenBank as described in Table 1.

Authors’ contributions

A.G.F. performed the download, all data processing and analysis, participated in the study design and wrote the manuscript; L.G.A helped in the processing and analysis of all data; A.S.F.F. helped in the processing, data analysis and correction of the manuscript in relation to the reverse vaccinology analysis; T.C.V.R, L.G.R.G, S.T, F.M.M, V.A, R.T.J.R helped in the preparation and execution of the docking analyses; A.K.J. helped in the preparation, execution of the docking analyses and helped in the writing of the manuscript; L.C.O. helped in the processing and analysis of the data; C.J.O. participated in manuscript review by contributing suggestions and corrections; S.d.C.S. designed, designed, coordinated the study and helped write the manuscript; L.d.J.B. designed and coordinated the study, helped with data processing and analysis, and helped write the manuscript.

Additional information

Funding

This work was supported by the Fundação de Amparo à Pesquisa do Estado Minas Gerais (FAPEMIG; Grant Number: APQ-01323-15), National Council for Scientific and Technological Development (CNPq) and Coordination for the Improvement of Higher Education Personnel (CAPES; Finance code 001).