scholarly journals Studies on Growth Characteristics and Cross-Neutralization of Wild-Type and Delta SARS-CoV-2 From Hisar (India)

2021 ◽  
Vol 11 ◽  
Author(s):  
Nitin Khandelwal ◽  
Yogesh Chander ◽  
Ram Kumar ◽  
Himanshu Nagori ◽  
Assim Verma ◽  
...  
Keyword(s):  
Life Cycle ◽  
Cytopathic Effect ◽  
Therapeutic Strategies ◽  
Growth Characteristics ◽  
Nucleotide Sequencing ◽  
Plaque Size ◽  
Wild Type ◽  
Cross Neutralization ◽  
In The Beginning ◽  
Prior Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly evolved to generate several antigenic variants. These variants have raised concerns whether pre-existing immunity to vaccination or prior infection would be able to protect against the newly emerging SARS-CoV-2 variants or not. We isolated SARS-CoV-2 from the coronavirus disease 2019 (COVID-19)-confirmed patients in the beginning of the first (April/May 2020) and second (April/May 2021) waves of COVID-19 in India (Hisar, Haryana). Upon complete nucleotide sequencing, the viruses were found to be genetically related with wild-type (WT) and Delta variants of SARS-CoV-2, respectively. The Delta variant of SARS-CoV-2 produced a rapid cytopathic effect (24–36 h as compared to 48–72 h in WT) and had bigger plaque size but a shorter life cycle (~6 h as compared to the ~8 h in WT). Furthermore, the Delta variant achieved peak viral titers within 24 h as compared to the 48 h in WT. These evidence suggested that the Delta variant replicates significantly faster than the WT SARS-CoV-2. The virus neutralization experiments indicated that antibodies elicited by vaccination are more efficacious in neutralizing the WT virus but significantly less potent against the Delta variant. Our findings have implications in devising suitable vaccination, diagnostic and therapeutic strategies, besides providing insights into understanding virus replication and transmission.

The chronicle of COVID-19: possible strategies to curb the pandemic

2020 ◽  
Vol 27 ◽  
Author(s):  
Rajesh Kumar ◽  
Seetha Harilal ◽  
Abdullah G. Al-Sehemi ◽  
Githa Elizabeth Mathew ◽  
Simone Carradori ◽  
...  
Keyword(s):  
Life Cycle ◽  
Research And Development ◽  
Vaccine Development ◽  
Therapeutic Strategies ◽  
Antiviral Drugs ◽  
Limited Data ◽  
Social Distancing ◽  
The World ◽  
Novel Virus ◽  
Day By Day

: COVID-19, an epidemic that emerged in Wuhan, has become a pandemic affecting worldwide and is in a rapidly evolving condition. Day by day, the confirmed cases and deaths are increasing many folds. SARS-CoV-2 is a novel virus; therefore, limited data are available to curb the disease. Epidemiological approaches, isolation, quarantine, social distancing, lockdown, and curfew are being employed to halt the spread of the disease. Individual and joint efforts all over the world are producing a wealth of data and information which are expected to produce therapeutic strategies against COVID-19. Current research focuses on the utilization of antiviral drugs, repurposing strategies, vaccine development as well as basic to advanced research about the organism and the infection. The review focuses on the life cycle, targets, and possible therapeutic strategies, which can lead to further research and development of COVID-19 therapy.

scholarly journals Isolation of a gene required for programmed initiation of development by Aspergillus nidulans.

1992 ◽  
Vol 12 (9) ◽  
pp. 3827-3833 ◽  
Author(s):  
T H Adams ◽  
W A Hide ◽  
L N Yager ◽  
B N Lee
Keyword(s):  
Life Cycle ◽  
Aspergillus Nidulans ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Nutrient Deprivation ◽  
Deletion Mutants ◽  
Wild Type ◽  
Microbial Development ◽  
Type Strains ◽  
Posttranscriptional Level

In contrast to many other cases in microbial development, Aspergillus nidulans conidiophore production initiates primarily as a programmed part of the life cycle rather than as a response to nutrient deprivation. Mutations in the acoD locus result in "fluffy" colonies that appear to grow faster than the wild type and proliferate as undifferentiated masses of vegetative cells. We show that unlike wild-type strains, acoD deletion mutants are unable to make conidiophores under optimal growth conditions but can be induced to conidiate when growth is nutritionally limited. The requirement for acoD in conidiophore development occurs prior to activation of brlA, a primary regulator of development. The acoD transcript is present both in vegetative hyphae prior to developmental induction and in developing cultures. However, the effects of acoD mutations are detectable only after developmental induction. We propose that acoD activity is primarily controlled at the posttranscriptional level and that it is required to direct developmentally specific changes that bring about growth inhibition and activation of brlA expression to result in conidiophore development.

scholarly journals Pharmacodynamics of Itraconazole against Aspergillus fumigatus in anIn VitroModel of the Human Alveolus: Perspectives on the Treatment of Triazole-Resistant Infection and Utility of Airway Administration

2012 ◽  
Vol 56 (8) ◽  
pp. 4146-4153 ◽  
Author(s):  
Zaid Al-Nakeeb ◽  
Ajay Sudan ◽  
Adam R. Jeans ◽  
Lea Gregson ◽  
Joanne Goodwin ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Therapeutic Strategies ◽  
Wild Type ◽  
Content Type ◽  
Exposure Response ◽  
Prevention And Treatment ◽  
Resistant Infection ◽  
Resistant Strains ◽  
Type Strains

ABSTRACTItraconazole is used for the prevention and treatment of infections caused byAspergillus fumigatus. An understanding of the pharmacodynamics of itraconazole against wild-type and triazole-resistant strains provides a basis for innovative therapeutic strategies for treatment of infections. Anin vitromodel of the human alveolus was used to define the pharmacodynamics of itraconazole. Galactomannan was used as a biomarker. The effect of systemic and airway administration of itraconazole was assessed, as was a combination of itraconazole administered to the airway and systemically administered 5FC. Systemically administered itraconazole against the wild type induced a concentration-dependent decline in galactomannan in the alveolar and endothelial compartments. No exposure-response relationships were apparent for the L98H, M220T, or G138C mutant. The administration of itraconazole to the airway resulted in comparable exposure-response relationships to those observed with systemic therapy. This was achieved without detectable concentrations of drug within the endothelial compartment. The airway administration of itraconazole resulted in a definite but submaximal effect in the endothelial compartment against the L98H mutant. The administration of 5FC resulted in a concentration-dependent decline in galactomannan in both the alveolar and endothelial compartments. The combination of airway administration of itraconazole and systemically administered 5FC was additive. Systemic administration of itraconazole is ineffective against Cyp51 mutants. The airway administration of itraconazole is effective for the treatment of wild-type strains and appears to have some activity against the L98H mutants. Combination with other agents, such as 5FC, may enable the attainment of near-maximal antifungal activity.

scholarly journals Borrelia burgdorferi Lacking BBK32, a Fibronectin-Binding Protein, Retains Full Pathogenicity

2006 ◽  
Vol 74 (6) ◽  
pp. 3305-3313 ◽  
Author(s):  
Xin Li ◽  
Xianzhong Liu ◽  
Deborah S. Beck ◽  
Fred S. Kantor ◽  
Erol Fikrig
Keyword(s):  
Life Cycle ◽  
Borrelia Burgdorferi ◽  
Deletion Mutant ◽  
Binding Protein ◽  
Kanamycin Resistance ◽  
Binding Activity ◽  
Mammalian Host ◽  
Wild Type ◽  
Fibronectin Binding Protein ◽  
Fibronectin Binding

ABSTRACT BBK32, a fibronectin-binding protein of Borrelia burgdorferi, is one of many surface lipoproteins that are differentially expressed by the Lyme disease spirochete at various stages of its life cycle. The level of BBK32 expression in B. burgdorferi is highest during infection of the mammalian host and lowest in flat ticks. This temporal expression profile, along with its fibronectin-binding activity, strongly suggests that BBK32 may play an important role in Lyme pathogenesis in the host. To test this hypothesis, we constructed an isogenic BBK32 deletion mutant from wild-type B. burgdorferi B31 by replacing the BBK32 gene with a kanamycin resistance cassette through homologous recombination. We examined both the wild-type strain and the BBK32 deletion mutant extensively in the experimental mouse-tick model of the Borrelia life cycle. Our data indicated that B. burgdorferi lacking BBK32 retained full pathogenicity in mice, regardless of whether mice were infected artificially by syringe inoculation or naturally by tick bite. The loss of BBK32 expression in the mutant had no adverse effect on spirochete acquisition (mouse-to-tick) and transmission (tick-to-mouse) processes. These results suggest that additional B. burgdorferi proteins can complement the function of BBK32, fibronectin binding or otherwise, during the natural spirochete life cycle.

scholarly journals Serine 229 Balances the Hepatitis C Virus Nonstructural Protein NS5A between Hypo- and Hyperphosphorylated States

2019 ◽  
Vol 93 (23) ◽  
Author(s):  
Chia-Ni Tsai ◽  
Ting-Chun Pan ◽  
Cho-Han Chiang ◽  
Chun-Chiao Yu ◽  
Shih-Han Su ◽  
...  
Keyword(s):  
Life Cycle ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Nonstructural Protein ◽  
Feedback Regulation ◽  
Wild Type ◽  
Serine Residue ◽  
Large Structures ◽  
Phosphorylation Level ◽  
In The Wild

ABSTRACT The nonstructural protein NS5A of hepatitis C virus (HCV) is a phosphorylated protein that is indispensable for viral replication and assembly. We previously showed that NS5A undergoes sequential serine S232/S235/S238 phosphorylation resulting in NS5A transition from a hypo- to a hyperphosphorylated state. Here, we studied functions of S229 with a newly generated antibody specific to S229 phosphorylation. In contrast to S232, S235, or S238 phosphorylation detected only in the hyperphosphorylated NS5A, S229 phosphorylation was found in both hypo- and hyperphosphorylated NS5A, suggesting that S229 phosphorylation initiates NS5A sequential phosphorylation. Immunoblotting showed an inverse relationship between S229 phosphorylation and S235 phosphorylation. When S235 was phosphorylated as in the wild-type NS5A, the S229 phosphorylation level was low; when S235 could not be phosphorylated as in the S235A mutant NS5A, the S229 phosphorylation level was high. These results suggest an intrinsic feedback regulation between S229 phosphorylation and S235 phosphorylation. It has been known that NS5A distributes in large static and small dynamic intracellular structures and that both structures are required for the HCV life cycle. We found that S229A or S229D mutation was lethal to the virus and that both increased NS5A in large intracellular structures. Similarly, the lethal S235A mutation also increased NS5A in large structures. Likewise, the replication-compromised S235D mutation also increased NS5A in large structures, albeit to a lesser extent. Our data suggest that S229 probably cycles through phosphorylation and dephosphorylation to maintain a delicate balance of NS5A between hypo- and hyperphosphorylated states and the intracellular distribution necessary for the HCV life cycle. IMPORTANCE This study joins our previous efforts to elucidate how NS5A transits between hypo- and hyperphosphorylated states via phosphorylation on a series of highly conserved serine residues. Of the serine residues, serine 229 is the most interesting since phosphorylation-mimicking and phosphorylation-ablating mutations at this serine residue are both lethal. With a new high-quality antibody specific to serine 229 phosphorylation, we concluded that serine 229 must remain wild type so that it can dynamically cycle through phosphorylation and dephosphorylation that govern NS5A between hypo- and hyperphosphorylated states. Both are required for the HCV life cycle. When phosphorylated, serine 229 signals phosphorylation on serine 232 and 235 in a sequential manner, leading NS5A to the hyperphosphorylated state. As serine 235 phosphorylation is reached, serine 229 is dephosphorylated, stopping signal for hyperphosphorylation. This balances NS5A between two phosphorylation states and in intracellular structures that warrant a productive HCV life cycle.

scholarly journals Targeting Oncogenic BRAF: Past, Present, and Future

Cancers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1197 ◽  
Author(s):  
Zaman ◽  
Wu ◽  
Bivona
Keyword(s):  
Kinase Inhibitors ◽  
Therapy Resistance ◽  
Resistance Mechanisms ◽  
Genetic Alterations ◽  
Therapeutic Strategies ◽  
Wild Type ◽  
Braf Mutations ◽  
Molecular Alterations ◽  
Mutant Braf

Identifying recurrent somatic genetic alterations of, and dependency on, the kinase BRAF has enabled a “precision medicine” paradigm to diagnose and treat BRAF-driven tumors. Although targeted kinase inhibitors against BRAF are effective in a subset of mutant BRAF tumors, resistance to the therapy inevitably emerges. In this review, we discuss BRAF biology, both in wild-type and mutant settings. We discuss the predominant BRAF mutations and we outline therapeutic strategies to block mutant BRAF and cancer growth. We highlight common mechanistic themes that underpin different classes of resistance mechanisms against BRAF-targeted therapies and discuss tumor heterogeneity and co-occurring molecular alterations as a potential source of therapy resistance. We outline promising therapy approaches to overcome these barriers to the long-term control of BRAF-driven tumors and emphasize how an extensive understanding of these themes can offer more pre-emptive, improved therapeutic strategies.

scholarly journals Scanning Mutagenesis Studies Reveal a Potential Intramolecular Interaction within the C-Terminal Half of Dengue Virus NS2A Involved in Viral RNA Replication and Virus Assembly and Secretion

2015 ◽  
Vol 89 (8) ◽  
pp. 4281-4295 ◽  
Author(s):  
Ren-Huang Wu ◽  
Ming-Han Tsai ◽  
Day-Yu Chao ◽  
Andrew Yueh
Keyword(s):  
Life Cycle ◽  
Dengue Virus ◽  
Virus Assembly ◽  
Intramolecular Interaction ◽  
Rna Replication ◽  
The Other ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Transmembrane Segments ◽  
Virus Life Cycle

ABSTRACTThe NS2A protein of dengue virus (DENV) has eight predicted transmembrane segments (pTMSs; pTMS1 to pTMS8). NS2A has been shown to participate in RNA replication, virion assembly, and the host antiviral response. However, the role of the amino acid residues within the pTMS regions of NS2A during the virus life cycle is poorly understood. In the study described here, we explored the function of DENV NS2A by introducing a series of double or triple alanine substitutions into the C-terminal half (pTMS4 to pTMS8) of NS2A in the context of a DENV infectious clone or subgenomic replicon. Fourteen (8 within pTMS8) of 35 NS2A mutants displayed a lethal phenotype due to impairment of RNA replication by a replicon assay. Three NS2A mutants with mutations within pTMS7, the CM20, CM25, and CM27 mutants, displayed similar phenotypes, low virus yields (>100-fold reduction), wild-type-like replicon activity, and low infectious virus-like particle yields by transienttrans-packaging experiments, suggesting a defect in virus assembly and secretion. The sequencing of revertant viruses derived from CM20, CM25, and CM27 mutant viruses revealed a consensus reversion mutation, leucine (L) to phenylalanine (F), at codon 181 within pTMS7. The introduction of an L181F mutation into a full-length NS2A mutant, i.e., the CM20, CM25, and CM27 constructs, completely restored wild-type infectivity. Notably, L181F also substantially rescued the other severely RNA replication-defective mutants with mutations within pTMS4, pTMS6, and pTMS8, i.e., the CM2, CM3, CM13, CM31, and CM32 mutants. In conclusion, the results revealed the essential roles of pTMS4 to pTMS8 of NS2A in RNA replication and/or virus assembly and secretion. The intramolecular interaction between pTMS7 and pTMS4, pTMS6, or pTMS8 of the NS2A protein was also implicated.IMPORTANCEThe reported characterization of the C-terminal half of dengue virus NS2A is the first comprehensive mutagenesis study to investigate the function of flavivirus NS2A involved in the steps of the virus life cycle. In particular, detailed mapping of the amino acid residues within the predicted transmembrane segments (pTMSs) of NS2A involved in RNA replication and/or virus assembly and secretion was performed. A revertant genetics study also revealed that L181F within pTMS7 is a consensus reversion mutation that rescues both RNA replication-defective and virus assembly- and secretion-defective mutants with mutations within the other three pTMSs of NS2A. Collectively, these findings elucidate the role played by NS2A during the virus life cycle, possibly through the intricate intramolecular interaction between pTMS7 and other pTMSs within the NS2A protein.

scholarly journals Two Chimeric Chromosomes of Streptomyces coelicolor A3(2) Generated by Single Crossover of the Wild-Type Chromosome and Linear Plasmid SCP1

2004 ◽  
Vol 186 (19) ◽  
pp. 6553-6559 ◽  
Author(s):  
Masayuki Yamasaki ◽  
Haruyasu Kinashi
Keyword(s):  
Genome Evolution ◽  
Streptomyces Coelicolor ◽  
Linear Plasmid ◽  
Nucleotide Sequencing ◽  
Inverted Repeats ◽  
Wild Type ◽  
Linear Chromosome ◽  
Terminal Inverted Repeats ◽  
Type Chromosome ◽  
Chromosomal Duplication

ABSTRACT Streptomyces coelicolor A3(2) strain 2106 carries a 1.85-Mb linear plasmid, SCP1′-cysD, in addition to a 7.2-Mb linear chromosome. Macrorestriction analysis indicated that both linear DNAs are hybrids of the wild-type chromosome and the linear plasmid SCP1 on each side. Nucleotide sequencing of the fusion junctions revealed no homology between the recombination regions. SCP1′-cysD contains an SCP1 telomere and a chromosomal telomere at each end and therefore does not have terminal inverted repeats. In addition, SCP1′-cysD could not be eliminated from strain 2106 by various mutagenic treatments. Thus, we concluded that both the 7.2-Mb chromosome and SCP1′-cysD are chimeric chromosomes generated by a single crossover of the wild-type chromosome and SCP1. This may be regarded as a model of chromosomal duplication in genome evolution.

Sign in / Sign up

Export Citation Format

Share Document