To be remembered: B cell memory response against SARS-CoV-2 and its variants in vaccinated and unvaccinated individuals.

COVID-19 disease has plagued the world economy and affected the overall well-being and life of most of the people. Natural infection as well as vaccination leads to the development of an immune response against the pathogen. This involves the production of antibodies, which can neutralize the virus during future challenges. In addition, the development of cellular immune memory with memory B and T cells provides long-lasting protection. The longevity of the immune response has been a subject of intensive research in this field. The extent of immunity conferred by different forms of vaccination or natural infections remained debatable for long. Hence, understanding the effectiveness of these responses among different groups of people can assist government organizations in making informed policy decisions. In this article, based on the publicly available data, we have reviewed the memory response generated by some of the vaccines against SARS-CoV-2 and its variants, particularly B cell memory in different groups of individuals.

Phytochemical Screening of Nyctanthes arbor-tristis Plant Extracts and Their Antioxidant and Antibacterial Activity Analysis.

Nyctanthes arbor-tristis, alias "Vishnu Parijat," is a medicinal plant used to treat various inflammation-associated ailments and to combat innumerable infections in the traditional system of medicine. In the present study, we collected the samples of N. arbor-tristis from the lower Himalayan region of Uttarakhand, India, and carried out their molecular identification through DNA barcoding. To examine the antioxidant and antibacterial activities, we prepared the ethanolic and aqueous extracts (from flowers and leaves) and performed their phytochemical analysis by using different qualitative and quantitative approaches. The phytoextracts showed marked antioxidant potential, as revealed by a comprehensive set of assays. The ethanolic leaf extract showed marked antioxidant potential towards DPPH, ABTS, and NO scavenging (IC50 = 30.75 ± 0.006, 30.83 ± 0.002, and 51.23 ± 0.009 µg/mL, respectively). We used TLC-bioautography assay to characterize different antioxidant constituents (based on their Rf values) in the chromatograms ran under different mobile phases. For one of the prominent antioxidant spots in TLC bioautography, GC-MS analysis identified cis-9-hexadecenal and n-hexadecanoic acid as the major constituents. Furthermore, in antibacterial study, the ethanolic leaf extract showed marked activity against Aeromonas salmonicida (113.40 mg/mL of extract was equivalent to 100 µg/mL of kanamycin). In contrast, the ethanolic flower extract showed considerable antibacterial activity against Pseudomonas aeruginosa (125.85 mg/mL of extract ≡100 µg/mL of kanamycin). This study presents the phylogenetic account and unravels the antioxidant-related properties and antibacterial potential of N. arbor-tristis.

A facile synthesis of palladium nanoparticles decorated bismuth oxybromide nanostructures with exceptional photo-antimicrobial activities.

Assessing the interaction between microbes and nanocatalysts for finding an inclusive, proactive and deep understanding of nanoparticles-based toxicity is vital for discovering their broad range of applications. Palladium based photocatalysts owing to their unique fundamental characteristics and brilliant physicochemical potential have gained immense interest in environment remediation as disinfection system. In the present study, we report synthesis of a novel palladium nanoparticles decorated bismuth oxybromide (Pd/BiOBr) nanostructures using an energy efficient solution-based method, having excellent photocatalytic antibacterial action. The synthesized nanomaterials was thoroughly characterized using various analytical techniques. The photocatalytic antibacterial efficiency of Pd/BiOBr was evaluated against some common pathogenic strains of Gram-positive and Gram-negative bacteria (Pseudomonas fluorescens, Pseudomonas aeruginosa, Escherichia coli, Aeromonas salmonicida, Salmonella typhimurium, Klebsiella pneumoniae, Bacillus subtilis). In our results Pd/BiOBr showed excellent photocatalytic disinfection efficacy with > 99.9% bacterial inactivation. A very low concentration of Pd/BiOBr (0.5 µg/mL) effectively inhibited the bacterial growth in response to just 2 h of visible light irradiation, while 1 µg/mL of Pd/BiOBr completely killed all the tested bacterial strains proving their magnificent bactericidal potential. The developed materials with exceptional antibacterial broad range efficiency can be used in different photocatalytic disinfection systems including water purification systems, biofilm exclusion and combating differential antibiotic resistance.

A Review of Anti-Cancer and Related Properties of Lichen-Extracts and Metabolites.

BACKGROUND: Lichens are a composite consortium of a fungus and an alga. The symbiotic organisms are naturally equipped with distinct characteristics as compared to constituting organisms separately. Lichens, due to their peculiar anatomy and physiology, are the reservoir of more than 600 unique secondary metabolites, also known as 'lichen substances'. Since ancient times, many ethnic groups from various parts of the world have known about the applications of lichens as major provenance of food/fodder, medicine, dyes, spices, perfumes, etc. Lichen substances have shown impressive antioxidant, antimicrobial, antiviral, anti-tumor, and antiinflammatory activities under experimental conditions. Usnic acid, a well-known metabolite found in several species of lichens, possesses potent antioxidant and anti-inflammatory activities. It also has significant antiproliferative potential, as revealed through testing in different cancer cell lines. Atranorin, Lecanoric acid, Norstictic acid, Lobaric acid, Stictic acid, Ramalin, Gyrophoric acid, Salazinic acid, Protolichesterinic, and Fumarprotocetraric acid are some of the other purified lichen-metabolites with potent anti-cancer activities. OBJECTIVE: This study presents an overview of lichen-derived extracts and compounds showing anti-cancer (or related) properties. METHOD: The review comprehends different studies (in vivo and in vitro) backing up the possibility of lichenextracts and metabolites towards their use as antioxidant, anti-proliferative, anti-inflammatory, and Epithelialmesenchymal transition (EMT) -inhibiting agents. RESULTS: Various studies carried out to date show that lichen-extracts and metabolites have a range of anti-cancer and related properties that include anti-oxidative, anti-inflammatory, anti-proliferative, pro-apoptotic, and the potential of inhibition of cancer-associated EMT that is responsible for drug resistance and metastasis of cancer cells in a substantial proportion of cases. CONCLUSION: Lichens are the repertoire of a plethora of lichen-metabolites with significant anti-cancer potential. However, some of the critical 'anti-cancer related' properties, such as the ability of EMT-inhibition and the potential of induction of apoptosis, are relatively less studied for several lichen compounds. Additionally, many lichen compounds need to be purified at a larger scale to explore their anti-cancer potential.

Adhesins in the virulence of opportunistic fungal pathogens of human.

Aspergillosis, candidiasis, and cryptococcosis are the most common cause of mycoses-related disease and death among immune-compromised patients. Adhesins are cell-surface exposed proteins or glycoproteins of pathogens that bind to the extracellular matrix (ECM) constituents or mucosal epithelial surfaces of the host cells. The forces of interaction between fungal adhesins and host tissues are accompanied by ligand binding, hydrophobic interactions and protein-protein aggregation. Adherence is the primary and critical step involved in the pathogenesis; however, there is limited information on fungal adhesins compared to that on the bacterial adhesins. Except a few studies based on screening of proteome for adhesin identification, majority are based on characterization of individual adhesins. Recently, based on their characteristic signatures, many putative novel fungal adhesins have been predicted using bioinformatics algorithms. Some of these novel adhesin candidates have been validated by in-vitro studies; though, most of them are yet to be characterised experimentally. Morphotype specific adhesin expression as well as tissue tropism are the crucial determinants for a successful adhesion process. This review presents a comprehensive overview of various studies on fungal adhesins and discusses the targetability of the adhesins and adherence phenomenon, for combating the fungal infection in a preventive or therapeutic mode.