Brevicillin, a novel lanthipeptide from the genus Brevibacillus with antimicrobial, antifungal, and antiviral activity.

AIM: This study was aimed to determine antimicrobial and antiviral activity of a novel lanthipeptide from a Brevibacillus sp. for disinfectant application. METHODS AND RESULTS: The antimicrobial peptide (AMP) was produced by a bacterial strain AF8 identified as a member of the genus Brevibacillus representing a novel species. Whole genome sequence analysis using BAGEL identified a putative complete biosynthetic gene cluster involved in lanthipeptide synthesis. The deduced amino acid sequence of lanthipeptide named as brevicillin, showed >30% similarity with epidermin. Mass determined by MALDI-MS and Q-TOF suggested posttranslational modifications like dehydration of all Ser and Thr amino acids to yield Dha and Dhb, respectively. Amino acid composition determined upon acid hydrolysis is in agreement with core peptide sequence deduced from the putative biosynthetic gene bvrAF8. Biochemical evidence along with stability features ascertained posttranslational modifications during formation of the core peptide. The peptide showed strong activity with 99% killing of pathogens at 12 µg ml-1 within 1 minute. Interestingly, it also showed potent anti-SARS-CoV-2 activity by inhibiting ∼99% virus growth at 10 µg ml-1 in cell culture-based assay. Brevicillin did not show dermal allergic reactions in BALB/c mice. CONCLUSION: This study provides detailed description of a novel lanthipeptide and demonstrates its effective antibacterial, antifungal and anti-SARS-CoV-2 activity.

Corrigendum: Curdlan Limits Mycobacterium tuberculosis Survival Through STAT-1 Regulated Nitric Oxide Production.

[This corrects the article DOI: 10.3389/fmicb.2019.01173.].

A novel plant lectin, NTL-125, interferes with SARS-CoV-2 interaction with hACE2.

COVID-19 caused by SARS-CoV-2 virus has had profound impact on the world in the past two years. Intense research is going on to find effective drugs to combat the disease. Over the past year several vaccines were approved for immunization. But SARS-CoV-2 being an RNA virus is continuously mutating to generate new variants, some of which develop features of immune escape. This raised serious doubts over the long-term efficacy of the vaccines. We have identified a unique mannose binding plant lectin from Narcissus tazetta bulb, NTL-125, which effectively inhibits SARS-CoV-2 replication in Vero-E6 cell line. In silico docking studies revealed that NTL-125 has strong affinity to viral Spike RBD protein, preventing it from attaching to hACE2 receptor, the gateway to cellular entry. Binding analyses revealed that all the mutant variants of Spike protein also have stronger affinity for NTL-125 than hACE2. The unique α-helical tail of NTL-125 plays most important role in binding to RBD of Spike. NTL-125 also interacts effectively with some glycan moieties of S-protein in addition to amino acid residues adding to the binding strength. Thus, NTL-125 is a highly potential antiviral compound of natural origin against SARS-CoV-2 and may serve as an important therapeutic for management of COVID-19.

Chlorhexidine: An effective anticovid mouth rinse.

CONTEXT: Dentists across the globe are witnessing a completely unforeseen and uncertain professional situation during these times of COVID-19 pandemic. There is conflicting evidence regarding the effectiveness of routinely used mouthwashes and especially Chlorhexidine, to reduce the viral load in oral cavity and the aerosols during oral procedures. AIMS: Comparative evaluation of the effectiveness of the current 'gold standard' chlorhexidine and povidone iodine as a control agent, through an in-vitro analysis. SETTINGS AND DESIGN: In-vitro laboratory analysis. METHODS AND MATERIAL: All the experiments for analysis of antiviral efficacy of chlorhexidine digluconate (2%)and povidone iodine(1%), against SARS-CoV-2 virus were performed in the BSL3 facility at the Council of Scientific and Industrial Research-Institute of Microbial Technology, using the VeroE6 cell lines. The analysis of the virus inactivation was based on quantification of viral RNA (Cycle threshold (Ct) profile) present in the culture supernatant using Real-Time Quantitative Reverse Transcription PCR (qRT-PCR). STATISTICAL ANALYSIS USED: Descriptive analysis (Statistical package for social sciences (SPSS Inc., Chicago, IL, version 15.0 for Windows). RESULTS: Chlorhexidine digluconate in 0.2% concentration inactivated more than 99.9% of SARS CoV 2 virus, in minimal contact time of 30 seconds, which was considered better efficacy than povidone-iodine utilized for 30 and 60 seconds. Subtle differences were observed in the activity of both the compounds in terms of percent inactivation of virus, though a greater relative change in Ct values was observed for chlorhexidine. CONCLUSIONS: Within the limitations of the present study, it can be concluded that Chlorhexidine digluconate in 0.2% concentration inactivated SARS CoV 2 in minimal contact time i.e 30 secs, however both compounds tested i.e Chlorhexidine and povidone-iodine were found to have antiviral activity against SARS CoV2 virus.

A multiple T cell epitope comprising DNA vaccine boosts the protective efficacy of Bacillus Calmette-Guérin (BCG) against Mycobacterium tuberculosis.

BACKGROUND: Approximately 80% - 90% of individuals infected with latent Mycobacterium tuberculosis (Mtb) remain protected throughout their life-span. The release of unique, latent-phase antigens are known to have a protective role in the immune response against Mtb. Although the BCG vaccine has been administered for nine decades to provide immunity against Mtb, the number of TB cases continues to rise, thereby raising doubts on BCG vaccine efficacy. The shortcomings of BCG have been associated with inadequate processing and presentation of its antigens, an inability to optimally activate T cells against Mtb, and generation of regulatory T cells. Furthermore, BCG vaccination lacks the ability to eliminate latent Mtb infection. With these facts in mind, we selected six immunodominant CD4 and CD8 T cell epitopes of Mtb expressed during latent, acute, and chronic stages of infection and engineered a multi-epitope-based DNA vaccine (C6). RESULT: BALB/c mice vaccinated with the C6 construct along with a BCG vaccine exhibited an expansion of both CD4 and CD8 T cell memory populations and augmented IFN-γ and TNF-α cytokine release. Furthermore, enhancement of dendritic cell and macrophage activation was noted. Consequently, illustrating the elicitation of immunity that helps in the protection against Mtb infection; which was evident by a significant reduction in the Mtb burden in the lungs and spleen of C6 + BCG administered animals. CONCLUSION: Overall, the results suggest that a C6 + BCG vaccination approach may serve as an effective vaccination strategy in future attempts to control TB.

Potential Role of Gut Microbiota in Induction and Regulation of Innate Immune Memory.

The gut microbiota significantly regulates the development and function of the innate and adaptive immune system. The attribute of immunological memory has long been linked only with adaptive immunity. Recent evidence indicates that memory is also present in the innate immune cells such as monocytes/macrophages and natural killer cells. These cells exhibit pattern recognition receptors (PRRs) that recognize microbe- or pathogen-associated molecular patterns (MAMPs or PAMPs) expressed by the microbes. Interaction between PRRs and MAMPs is quite crucial since it triggers the sequence of signaling events and epigenetic rewiring that not only play a cardinal role in modulating the activation and function of the innate cells but also impart a sense of memory response. We discuss here how gut microbiota can influence the generation of innate memory and functional reprogramming of bone marrow progenitors that helps in protection against infections. This article will broaden our current perspective of association between the gut microbiome and innate memory. In the future, this knowledge may pave avenues for development and designing of novel immunotherapies and vaccination strategies.

Curdlan Limits Mycobacterium tuberculosis Survival Through STAT-1 Regulated Nitric Oxide Production.

Host-directed therapies have emerged as an innovative and promising approach in tuberculosis (TB) treatment due to the observed limitations of current TB regimen such as lengthy duration and emergence of drug resistance. Thus, we explored the role of curdlan (beta glucan polysaccharide) as a novel strategy to activate macrophages against Mycobacterium tuberculosis (Mtb). The aim of the study was to investigate the role of curdlan in restricting the Mtb growth both in vitro and in vivo. Further, the immunomodulatory potential of curdlan against Mtb and the underlying mechanism is largely unknown. We found that curdlan treatment enhanced the antigen presentation, pro-inflammatory cytokines, Mtb uptake and killing activity of macrophages. In vivo studies showed that curdlan therapy significantly reduced the Mtb burden in lung and spleen of mice. Administration of curdlan triggered the protective Th1 and Th17 immunity while boosting the central and effector memory response in Mtb infected mice. Curdlan mediated anti-Mtb activity is through signal transducer and activator of transcription-1 (STAT-1), which regulates nitric oxide (NO) production through inducible NO synthase (iNOS) induction; along with this activation of nuclear factor kappa B (NF-κB) was also evident in Mtb infected macrophages. Thus, we demonstrate that curdlan exerts effective anti-tuberculous activity anti-tuberculous activity. It can be used as a potential host-directed therapy against Mtb.