Shankar, U. | bioRxiv Science

bioRxiv2020

Scrutinizing the SARS-CoV-2 protein information for the designing an effective vaccine encompassing both the T-cell and B-cell epitopes

Novel SARS coronavirus (SARS-CoV-2) has caused a pandemic condition world-wide and has been declared as public health emergency of International concern by WHO in a very short span of time. The community transmission of this highly infectious virus has severely affected various parts of China, Italy, Spain and USA among others. The prophylactic solution against SARS-CoV-2 infection is challenging due to the high mutation rate of its RNA genome. Herein, we exploited a next generation vaccinology approach to construct a multi-epitope vaccine candidate against SARS-CoV-2 with high antigenicity, safety and efficacy to combat this deadly infectious agent. The whole proteome was scrutinized for the screening of highly conserved, antigenic, non-allergen and non-toxic epitopes having high population coverage that can elicit both humoral and cellular mediated immune response against COVID-19 infection. These epitopes along with four different adjuvants were utilized to construct a multi-epitope vaccine candidate that can generate strong immunological memory response having high efficacy in humans. Various physiochemical analyses revealed the formation of a stable vaccine product having a high propensity to form a protective solution against the detrimental SARS-CoV-2 strain with high efficacy. The vaccine candidate interacted with immunological receptor TLR3 with high affinity depicting the generation of innate immunity. Further, the codon optimization and in silico expression show the plausibility of the high expression and easy purification of the vaccine product. Thus, this present study provides an initial platform of the rapid generation of an efficacious protective vaccine for combating COVID-19.

immunology↗

bioRxiv2018

G-quadruplex stabilization in the ions and maltose transporters inhibit Salmonella enterica growth and virulence.

The G-quadruplex structure forming motifs have recently emerged as a novel therapeutic drug target in various human pathogens. Herein, we report three highly conserved G-quadruplex motifs (SE-PGQ-1, 2, and3) in genome of all the 412 strains of Salmonella enterica. Bioinformatics analysis inferred the presence of SE-PGQ-1 in the regulatory region of mgtA, presence of SE-PGQ-2 in the open reading frame of entA and presence of SE-PGQ-3 in the promoter region of malE and malK genes. The products of mgtA and entA are involved in transport and homeostasis of Mg2+ and Fe3+ ion and thereby required for bacterial survival in the presence of reactive nitrogen/oxygen species produced by the host macrophages, whereas, malK and malE genes are involved in transport of maltose sugar, that is one of the major carbon source in the gastrointestinal tract of human. The formation of stable intramolecular G-quadruplex structures by SE-PGQs was confirmed by employing CD, EMSA and NMR spectroscopy. Cellular studies revealed the inhibitory effect of 9-amino acridine on Salmonella enterica growth. Next, CD melting analysis demonstrated the stabilizing effect of 9-amino acridine on SE-PGQs. Further, polymerase inhibition and RT-qPCR assays emphasize the biological relevance of predicted G-quadruplex in the expression of PGQ possessing genes and demonstrate the G-quadruplexes as a potential drug target for the devolping novel therapeutics for combating Salmonella enterica infection.\n\nAuthor SummarySince last several decades scientific community has witnessed a rapid increase in number of such human pathogenic bacterial species that acquired resistant to multiple antibacterial agents. Currently, emergence of multidrug-resistant strains remain a major public health concern for clinical investigators that rings a global alarm to search for novel and highly conserved drug targets. Recently, G-quadruplex structure forming nucleic acid sequences were endorsed as highly conserved Drug target for preventing infection of several human pathogens including viral and protozoan species. Therefore, here we explored the presence G-quadruplex forming motif in genome of Salmonella enterica bacteria that causes food poisoning, and enteric fever in human. The formation of intra molecular G-quadruplex structure in four genes (mgtA, entA, malE and malK) was confirmed by NMR, CD and EMSA. The 9-amino acridine, a known G-quadruplex binder has been shown to stabilize the predicted G-quadruplex motif and decreases the expressioin of G-quadruplex hourbouring genes using RT-PCR and cellular toxicity assay. This study concludes the presence of G-quadruplex motifs in essential genes of Salmonella enterica genome as a novel and conserved drug target and 9-amino acridine as candidate small molecule for preventing the infection of Salmonella enterica using a G4 mediated inhibition mechanism.

genomics↗