Koteswara Rao Vamkudoth

The highly virulent and transmissible SARS-CoV-2 causes COVID-19 and poses a global public health threat. Herein cloned, expressed, and the molecular weight of the receptor-binding domain (RBD) of the SARS-CoV-2 gene encoding protein was confirmed by SDS–PAGE electrophoresis and Western blot analysis. The pivotal aim is to develop single-stranded DNA (ssDNA) aptamers for the rapid detection of SARS-COV-2 infections in humans. In this investigation, a library of nine novel ssDNA aptamers was developed by several rounds of systematic evolution of ligands by an exponential enrichment approach and assessed by an enzyme-linked aptamer assay for binding affinity against RBD antigen (Ag). An in vitro assay resulted in a varied colorimetric signal that depends on the nature of aptamer. Quantitative determination of AptRBD3, AptRBD6, and AptRBD8 aptamers exhibited excellent binding affinity against Ag in the range of 5–10 ng/mL. The putative AptRBD3, AptRBD6, and AptRBD8 aptamers were converted into peptide sequences and docked against RBD, exhibiting good binding energy of −6.8, −6.3, and −7.1 kcal/mol respectively, which were recorded. Furthermore, docking studies of ssDNA aptamers were performed using HDOCK web server to ascertain the binding mechanism and docking score perceived as −389.74, −404.28, and −390.37. Despite this, we engineered a high-affinity AptRBD3.3 aptamer that formed a single and bulged loop, which improved binding affinity, resulted in a docking score of −361.56, and exhibited sensitivity at 4 ng of Ag of SARS-CoV-2. Moreover, computational modeling of AptRBD3.3 revealed an intriguing significant binding affinity with the RBD mutant SARS-CoV-2 S-UK variant (PDB ID: 7EDG) with a docking score of −350.21. In conclusion, the AptRBD3.3 aptamer can be used for the development of lateral flow device and electrochemical sensors for rapid, low-cost, and accurate detection of COVID-19 infection in humans for point of care diagnostics.

The rapid rise of antimicrobial resistance (AMR) is a global concern, being triggered by the overuse or misuse of antibiotics in poultry farming sector. We evaluated Lactococcus lactis subsp. lactis BIONCL17752 strain, and characterized its probiotic potential to endure hostile gastrointestinal conditions. Genome sequencing analysis revealed probiotics traits, and gene clusters involved in bacteriocins, lactococcin A, and sactipeptides production. The absence of genes for antibiotic resistance, virulence, and biogenic amine production indicates the potential of probiotic strain. The BIONCL17752 strain was explored for antibiotic-free feed supplement for growth promotor in broiler chicken. The feed supplemented with 4 × 10⁹ CFU/kg of probiotic strain, in combination with various concentrations of fructooligosaccharides (FOS) 1.0, 2.5, and 5.0 kg/tonne in starter, grower, and finisher diets, respectively. A significant improvement of body weight 152 to 171 g/bird (p < 0.05), and a low feed conversion ratio (FCR) of 1.62, was achieved without using synthetic antibiotics for growth promotion. The results of biochemical, hematological, and histological examinations showed normal features, indicating that the treatment had no harmful effects on the bird’s health. Reduced levels of cholesterol, triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) in serum are an indication of the health benefits for the treated birds. Microbial community analysis of fecal samples of poultry birds exhibited a higher abundance of Bacteroidetes, Firmicutes, Proteobacteria, Actinobacteria, and Fusobacteria. Probiotic treatment resulted in reduced Firmicutes and increased Bacteroidetes (F/B ratio) in the broiler’s gut which highlights the benefits of probiotic dietary supplements. Importantly, the probiotic-fed group exhibited a high abundance of carbohydrate-active enzymes (CAZyme) such as glycoside hydrolases (GH), glycoside transferases (GT), and carbohydrate-binding module (CBM) hydrolases which are essential for the degradation of complex sugar molecules. The probiotic potential of the BIONCL17752 strain contributes to broilers’ health by positively affecting intestinal microbiota, achieving optimal growth, and lowering mortality, demonstrating the economic benefits of probiotic treatment in organic poultry farming.

[This corrects the article DOI: 10.1021/acsomega.0c02813.].