Expression of novel fusion antiviral proteins ricin a chain-pokeweed antiviral proteins (RTA-PAPs) in Escherichia coli and their inhibition of protein synthesis and of hepatitis B virus in vitro

The limitations of virus-specific antiviral drugs became apparent during the current COVID-19 pandemic. The search for broad range antiviral proteins of a new kind to answer current and future pandemics has become an even more pressing matter. Here, the author further describes the expected anti-SARS-CoV-2 mechanisms of a novel broad range antiviral chimeric protein constructed between ricin A chain and pokeweed antiviral proteins. The latest in protein-ligand docking software were used to determine binding affinity of RTA-PAPs to SARS-CoV-2 frameshift stimulation element and elucidate the preferential post-infection entry mechanisms of RTA-PAPs into virus infected cells over non-infected ones, by doing a comparative analysis between in vitro and in silico results on numerous viruses. The results obtained strongly suggest that the post-infection preferential entry of RTA-PAPs into infected cells is mediated by the presence of viroporins integrated into the host cell membrane. The discovery of this mechanism revealed RTA-PAPs, and proteins like them, to be a new class of broad range antivirals that target with high specificity viroporin producing viruses, and with gain of functions in antiviral activities, post-infection.

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Selective destruction of nerve growth factor receptor-bearing cells in vitro using a hybrid toxin composed of ricin A chain and a monoclonal antibody against the nerve growth factor receptor.

The Journal of Cell Biology ◽

10.1083/jcb.101.3.1107 ◽

1985 ◽

Vol 101 (3) ◽

pp. 1107-1114 ◽

Cited By ~ 30

Author(s):

P S DiStefano ◽

J B Schweitzer ◽

M Taniuchi ◽

E M Johnson

Keyword(s):

Protein Synthesis ◽

Nerve Growth Factor ◽

Growth Factor ◽

Growth Factor Receptor ◽

Ricin A Chain ◽

Nerve Growth ◽

Ngf Receptor ◽

A Chain ◽

Ricin A

A hybrid toxin composed of ricin A chain and a monoclonal antibody directed against the rat nerve growth factor (NGF) receptor (192-IgG) was prepared using the heterobifunctional cross-linking agent N-succinimidyl-3-(2-pyridyldithio)-propionate and purified by affinity chromatography. Characterization studies showed that the hybrid, 192-s-s-A, displaced bound 125I-labeled 192-IgG from rat superior cervical ganglion (SCG) membranes with an IC50 3-5 times lower than that of unconjugated 192-IgG. When incubated with cultured rat SCG neurons, 192-s-s-A inhibited protein synthesis in a concentration-dependent fashion. The effect of 192-s-s-A on these neurons was reversed by coincubation with an excess of 192-IgG. The IC50 of 192-s-s-A on protein synthesis in rat SCG neurons was 4 nM. Intact ricin and ricin A chain inhibited protein synthesis in these neurons with IC50 values of 5 pM and 500 nM, respectively. The 192-s-s-A hybrid had no effect on mouse SCG neurons or a human melanoma cell line known to have NGF receptors. This is consistent with the finding that 192-IgG recognizes only the rat NGF receptor. Also, 192-s-s-A did not inhibit protein synthesis in primary cultures of rat skeletal muscle or Vero cells, which do not have cell surface receptors for NGF. 192-s-s-A was able to inhibit protein synthesis in PC12 cells but the potency was 10-100 times less in these cells compared to rat SCG neurons. Ricin and A chain were also 10-100 times less potent in PC12 cells than neurons. Rat SCG neurons exposed to 192-s-s-A lost their refractile appearance under phase-contrast optics, showed granular degeneration of neurites, and died. Thus the decreased protein synthesis caused by the hybrid toxin correlated with the morphological destruction of the neurons. 192-s-s-A represents a potentially powerful tool by which to selectively destroy NGF receptor-bearing cells in vitro. The hybrid toxin may prove useful as an in vivo toxin.

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Green tea extract and its major component epigallocatechin gallate inhibits hepatitis B virus in vitro

Antiviral Research ◽

10.1016/j.antiviral.2007.11.011 ◽

2008 ◽

Vol 78 (3) ◽

pp. 242-249 ◽

Cited By ~ 54

Author(s):

Jun Xu ◽

Jue Wang ◽

Fei Deng ◽

Zhihong Hu ◽

Hualin Wang

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Green Tea ◽

Epigallocatechin Gallate ◽

Green Tea Extract ◽

B Virus ◽

Tea Extract

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Generation of Full-Length Functional Antibody against PreS2 of Hepatitis B Virus in Hepatic Cells In Vitro from Bicistrons Mediated by Gutless Adenovirus

BioDrugs ◽

10.2165/11316940-000000000-00000 ◽

2009 ◽

Vol 23 (6) ◽

pp. 391-397

Author(s):

Yuexiang Yin ◽

Fang Lin ◽

Qiang Zhuang ◽

Li Liu ◽

Cheng Qian

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Full Length ◽

Hepatic Cells ◽

B Virus

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Epitope–Paratope Interaction of a Neutralizing Human Anti-Hepatitis B Virus PreS1 Antibody That Recognizes the Receptor-Binding Motif

Vaccines ◽

10.3390/vaccines9070754 ◽

2021 ◽

Vol 9 (7) ◽

pp. 754

Author(s):

Jisu Hong ◽

Youngjin Choi ◽

Yoonjoo Choi ◽

Jiwoo Lee ◽

Hyo Jeong Hong

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Receptor Binding ◽

Neutralizing Antibody ◽

Hbv Infection ◽

Binding Motif ◽

Alanine Scanning Mutagenesis ◽

B Virus ◽

Complementarity Determining Regions

Hepatitis B virus (HBV) is a global health burden that causes acute and chronic hepatitis. To develop an HBV-neutralizing antibody that effectively prevents HBV infection, we previously generated a human anti-preS1 monoclonal antibody (1A8) that binds to genotypes A–D and validated its HBV-neutralizing activity in vitro. In the present study, we aimed to determine the fine epitope and paratope of 1A8 to understand the mechanism of HBV neutralization. We performed alanine-scanning mutagenesis on the preS1 (aa 19–34, genotype C) and the heavy (HCDR) and light (LCDR) chain complementarity-determining regions. The 1A8 recognized the three residues (Leu22, Gly23, and Phe25) within the highly conserved receptor-binding motif (NPLGFFP) of the preS1, while four CDR residues of 1A8 were critical in antigen binding. Structural analysis of the epitope–paratope interaction by molecular modeling revealed that Leu100 in the HCDR3, Ala50 in the HCDR2, and Tyr96 in the LCDR3 closely interacted with Leu22, Gly23, and Phe25 of the preS1. Additionally, we found that 1A8 also binds to the receptor-binding motif (NPLGFLP) of infrequently occurring HBV. The results suggest that 1A8 may broadly and effectively block HBV entry and thus have potential as a promising candidate for the prevention and treatment of HBV infection.

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