In modern drug discovery, molecular docking analysis is routinely used to understand and predict the interaction between a drug molecule and a target protein from a microbe. Drugs identified in this way may inhibit the entry and replication of pathogens in host cells. The SARS-CoV-2 associated coronavirus disease, COVID-19, has become the most contagious and deadly pandemic disease in the world today. In abeyance of any specific vaccine or therapeutic against SARS-CoV-2, the burgeoning situation urges a need for effective drugs to treat the virus-infected patients. Herbal medicines have been used as natural remedies for treating various infectious diseases since ancient times. The spike (S) protein of SARS-CoV-2 is important for the attachment and pathogenesis of the virus. Therefore, this study focused on the search of useful ligands for S protein among active constituents present in common herbs that could serve as efficient remedies for COVID-19. We analysed the binding efficiency of twelve compounds present in common herbs with the S protein of SARS-CoV-2 through molecular docking analysis and also results are validated with two different docking tools. The binding efficiency of ligands was scored based on their predicted pharmacological interactions coupled with binding energy estimates. In docking analysis, compound “I” (Epigallocatechin gallate (EGCG)) was found to have the highest binding affinity with the viral S protein, followed by compounds, “F” (Curcumin),“D” (Apigenin) and “E” (Chrysophanol). The present study corroborates that compound “I” (EGCG) mostly present in the integrants of green tea, shows the highest potentiality for acting as an inhibitor of SARS-CoV-2. Further, characterization of the amino acid residues comprising the viral binding site and the nature of the hydrogen bonding involved in the ligand-receptor interaction revealed significant findings with herbal compound “I” (EGCG) binding to the S protein at eight amino acid residues. The binding sites are situated near to the amino acids which are required for virus pathogenicity. The findings of the present study need in vivo experiments to prove the utility of “I”, “F”,“D” and “E” compounds and their further use in making herb-based anti-SARS-CoV-2 product in near future. This analysis may help to create a new ethno-drug formulation for preventing or curing the COVID-19.

Francisella (F.) tularensis is a highly virulent, Gram-negative bacterial pathogen and the causative agent of the zoonotic disease tularemia. Here, we generated, analyzed and characterized a high quality circular genome sequence of the F. tularensis subsp. holarctica strain 12T0050 that caused fatal tularemia in a hare. Besides the genomic structure, we focused on the analysis of oriC, unique to the Francisella genus and regulating replication in and outside hosts and the first report on genomic DNA methylation of a Francisella strain. The high quality genome was used to establish and evaluate a diagnostic whole genome sequencing pipeline. A genotyping strategy for F. tularensis was developed using various bioinformatics tools for genotyping. Additionally, whole genome sequences of F. tularensis subsp. holarctica isolates isolated in the years 2008–2015 in Germany were generated. A phylogenetic analysis allowed to determine the genetic relatedness of these isolates and confirmed the highly conserved nature of F. tularensis subsp. holarctica.

Clostridium (C.) chauvoei is a Gram-positive, spore forming, anaerobic bacterium. It causes black leg in ruminants, a typically fatal histotoxic myonecrosis. High quality circular genome sequences were generated for the C. chauvoei type strain DSM 7528(T) (ATCC 10092(T)) and a field strain 12S0467 isolated in Germany. The origin of replication (oriC) was comparable to that of Bacillus subtilis in structure with two regions containing DnaA boxes. Similar prophages were identified in the genomes of both C. chauvoei strains which also harbored hemolysin and bacterial spore formation genes. A CRISPR type I-B system with limited variations in the repeat number was identified. Sporulation and germination process related genes were homologous to that of the Clostridia cluster I group but novel variations for regulatory genes were identified indicative for strain specific control of regulatory events. Phylogenomics showed a higher relatedness to C. septicum than to other so far sequenced genomes of species belonging to the genus Clostridium. Comparative genome analysis of three C. chauvoei circular genome sequences revealed the presence of few inversions and translocations in locally collinear blocks (LCBs). The species genome also shows a large number of genes involved in proteolysis, genes for glycosyl hydrolases and metal iron transportation genes which are presumably involved in virulence and survival in the host. Three conserved flagellar genes (fliC) were identified in each of the circular genomes. In conclusion this is the first comparative analysis of circular genomes for the species C. chauvoei, enabling insights into genome composition and virulence factor variation.