The β-coronavirus SARS-CoV-2 has caused a global pandemic. Affinity reagents targeting the SARS-CoV-2 spike protein are of interest for the development of therapeutics and diagnostics. We used affinity selection–mass spectrometry for the rapid discovery of synthetic high-affinity peptide binders for the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. From library screening with 800 million synthetic peptides, we identified three sequences with nanomolar affinities (dissociation constants K d = 80–970 nM) for RBD and selectivity over human serum proteins. Nanomolar RBD concentrations in a biological matrix could be detected using the biotinylated lead peptide in ELISA format. These peptides do not compete for ACE2 binding, and their site of interaction on the SARS-CoV-2-spike-RBD might be unrelated to the ACE2 binding site, making them potential orthogonal reagents for sandwich immunoassays. These findings serve as a starting point for the development of SARS-CoV-2 diagnostics or conjugates for virus-directed delivery of therapeutics.

When skeletons of Win compounds were used as templates, computer-assisted drug design led to the identification of a novel series of imidazolidinone derivatives with significant antiviral activity against enterovirus 71 (EV 71), the infection of which had resulted in about 80 fatalities during the 1998 epidemic outbreak in Taiwan. In addition to inhibiting all the genotypes (A, B, and C) of EV 71 in the submicromolar to low micromolar range, compounds 1 and 8 were extensively evaluated against a variety of viruses, showing potent activity against coxsackievirus A9 (IC(50) = 0.47-0.55 microM) and coxsackievirus A24 (IC(50) = 0.47-0.55 microM) as well as moderate activity against enterovirus 68 (IC(50) = 2.13 microM) and echovirus 9 (IC(50) = 2.6 microM). Our SAR studies revealed that imidazolidinone analogues with an aryl substituent at the para position of the phenoxyl ring, such as compounds 20, 21, 27, 57, 58, and 61, in general exhibited the highest activity against EV 71. Among them, compound 20 and its corresponding hydrochloride salt 57, in terms of potency and selectivity index, appear to be the most promising candidates in this series for further development of anti-EV-71 agents. Preliminary results of the study on the mode of action by a time-course experiment suggest that test compounds 1 and 8 can effectively inhibit the virus replication at the early stages, referring to virus attachment or uncoating. This indicates that the surface protein may be the target for this type of compounds.

Enterovirus 71 is one of the most important pathogens in the family of Picornaviridae that can cause severe complications in the postpoliovirus era, such as encephalitis, pulmonary edema, and even death. Pyridyl imidazolidinone is a novel class of potent and selective human enterovirus 71 inhibitor. Pyridyl imidazolidinone was identified by using computer-assisted drug design. This virologic investigation demonstrates that BPR0Z-194, one of the pyridyl imidazolidinones, targets enterovirus 71 capsid protein VP1. Time course experiments revealed that BPR0Z-194 effectively inhibited virus replication in the early stages, implying that the compound can inhibit viral adsorption and/or viral RNA uncoating. BPR0Z-194 was used to select and characterize the drug-resistant viruses. Sequence analysis of the VP1 region showed that the resistant variants differed consistently by seven amino acids in VP1 region from their parental drug-sensitive strains. Sitedirected mutagenesis of enterovirus 71 infectious cDNA revealed that a single amino acid alteration at the position 192 of VP1 can confer resistance to the inhibitory effects of BPR0Z-194.Enterovirus 71 (EV71) was first isolated in 1969 in California (J. Blomberg, E. Lycke, K. Ahlfors, T. Johnsson, S. Wolontis, and G. von Zeipel, Letter, Lancet i:112). Two adults and 18 children were infected in that outbreak and one 5-year-old child died. Thereafter, mortalities caused by EV71 were reported in Bulgaria (6), Hungary (23), and Malaysia. In 1998, an EV71 epidemic occurred in Taiwan, with the virus infecting over 120,000 people and killing 78 children (1,5,13,14). The central nervous system is the most vulnerable target of EV71 infection. After the central nervous system is virus infected, a patient can die very quickly from severe complications, such as encephalitis (19) and pulmonary edema (2, 16).EV71, like other viruses in the family of Picornaviridae, is a small, nonenveloped, spherical particle with a diameter of ϳ30 nm. The virus has a single-stranded positive-sense RNA enclosed by the capsid proteins VP1, VP2, VP3, and VP4. The capsid contains 60 structural proteins symmetrically arranged into an icosahedral lattice (15,31,32). In addition to protecting the viral RNA from nuclease cleavage, the capsid recognizes the receptors on the surface of the specific host cells (3, 9, 18) and displays antigenicity (20,38). The surface of the virion has a prominent star-shaped plateau at the fivefold axis of symmetry, surrounded by a deep depression ("canyon"). The canyon has been shown to serve as a receptor-binding site in poliovirus and rhinovirus (29,30).Pleconaril, one of the WIN compounds with capsid-binding capability targeting VP1, is a novel agent for treating picornavirus infections. Pleconaril has passed the last stage of clinical trials (4, 26) and has shown excellent antiviral effects for most of the enteroviruses and rhinoviruses (27,28,33,34). However, pleconaril did not neutralize the cytopathic effect (CPE) induced by EV71 (37). Therefore, a series of imidazol...

Abstract:The scientific literature of nanoparticle drug delivery technologies (NDDT) between 2005 and 2014 was reviewed. The visualized co-citation network of its knowledge domain was characterized in terms of thematic concentrations of co-cited references and emerging trends of surging keywords and citations to references through a scientometric review. The combined dataset of 25,171 bibliographic records were constructed through topic search and citation expansion to ensure adequate coverage of the field. While research in gold nanoparticle and magnetic nanoparticle remains the two most prominent knowledge domains in the NDDT field, research related to clinical and therapeutic applications has experienced a considerable growth. In particular, clinical and therapeutic developments in NDDT have demonstrated profound connections with the mesoporous silica nanoparticle research and microcrystal research. A rapid adaptation of mesoporous silica-based nanomaterials and rare earth fluoride nano-/microcrystal in NDDT is evident. Innovative strategies have been employed to exploit the multicomponent, chemical synthesis, surface modification, and controlled release imparting functionalized targeting capabilities. This study not only facilitated the connection of authors and research themes in the NDDT community, but also demonstrated how research interests and trends evolve over time, which greatly contributes to our understanding of the NDDT knowledge domains.