Bioactive phytocompounds against specific target proteins of Borrelia recurrentis responsible for louse-borne relapsing fever: Genomics and structural bioinformatics evidence.

Louse-borne relapsing fever (LBRF) with high untreated mortality caused by spirochete Borrelia recurrentis is predominantly endemic to Sub-Saharan Africa and has re-emerged in parts of Eastern Europe, Asia and Latin America due to population migrations. Despite subtractive evolution of lice-borne pathogenic Borrelia spp. from tick-borne species, there has been no comprehensive report on conservation of protein targets across tick and lice-borne pathogenic Borrelia nor exploration of phytocompounds that are toxic to tick against lice. From the 19 available whole genomes including B. recurrentis, B. burgdorferi, B. hermsii, B. parkeri and B. miyamotoi, conservation of seven drug targets (>80% domain identity) viz. 30 S ribosomal subunit proteins (RSP) S3, S7, S8, S14, S19, penicillin-binding protein-2 and 50 S RSP L16 were deciphered through multiple sequence alignments. Twelve phytocompounds (hydroxy-tyrosol, baicalein, cis-2-decanoic acid, morin, oenin, rosemarinic acid, kaempferol, piceatannol, rottlerin, luteolin, fisetin and monolaurin) previously explored against Lyme disease spirochete B. burgdorferi when targeted against LBRF-causing B. recurrentis protein targets revealed high multi-target affinity (2%-20% higher than conventional antibiotics) through molecular docking. However, based on high binding affinity against all target proteins, stable coarse-grained dynamics (fluctuations <1 Å) and safe pharmacological profile, luteolin was prioritized. The study encourages experimental evaluation of the potent phytocompounds and similar protocols for investigating other emerging vector-borne diseases.