Genetic Analysis of LigA, LipL32, Loa22, and OmpL1 Antigens from Leptospira spp. Sejroe Serogroup: How Close We Are To a Vaccine Against Bovine Leptospirosis?

Bovine leptospirosis has as main causative agents Leptospira spp. from Sejroe serogroup. Vaccination is a crucial step to control this infection. The use of conserved proteins among Leptospira spp. is of great importance for a protective immune response. The aim of the present study is to genetically analyze antigens of Leptospira spp. from Sejroe serogroup strains isolated from cattle for a preliminary evaluation of vaccine candidates. Genes associated with antigenicity-LigA, LipL32, Loa22, and OmpL1-were analyzed through bioinformatic and immunoinformatic tools. Despite high diversity observed in strains, on an amino acid level, highly conserved regions were observed (> 90%), particularly in LipL32 gene. Moreover, highly conserved amino acid regions (> 30 aa) were observed in all genes, regardless of species, geographical origin or biological source of isolation. Superposed structures of protein fragments including all the predicted MHC-II and B-Cell epitopes were demonstrated. Results presented herein are preliminary, but a fundamental step towards the development of an efficient vaccine against bovine leptospirosis, a silent but enormously concerning disease.