Antiviral Peptides Delivered by Chitosan-Based Nanoparticles to Neutralize SARS-CoV-2 and HCoV-OC43

Protein Nanoparticles for Targeted SARS-CoV-2 Trapping and Neutralization

The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to challenge global health despite widespread vaccination efforts, underscoring the need for innovative strategies to combat emerging infectious diseases effectively. Herein, LCB1-NPs and LCB3-NPs are engineered as a novel class of protein-only nanoparticles formed through coiled coil-driven self-assembly and tailored to interact specifically with the SARS-CoV-2 spike protein. The multivalency of LCB1-NPs and LCB3-NPs offers a strategy for efficiently targeting and neutralizing SARS-CoV-2 both in solution and when immobilized on surfaces. It is demonstrated that LCB1-NPs and LCB3-NPs bind to the SARS-CoV-2 spike protein's receptor-binding domain (RBD) with high affinity, effectively blocking the entry of SARS-CoV-2 virus-like particles into angiotensin-converting enzyme 2 (ACE2)-coated human cells. The cost-effectiveness, scalability, and straightforward production process of these protein nanoparticles make them suitable for developing novel anti-viral materials. Accordingly, it is shown how these nanostructures can be packed into columns to build up economic and highly potent trapping devices for SARS-CoV-2 adsorption.

Applications of Chitosan in Prevention and Treatment Strategies of Infectious Diseases

Chitosan is the most commonly investigated functional cationic biopolymer in a wide range of medical applications due to its promising properties such as biocompatibility, biodegradability, and bioadhesivity, as well as its numerous bioactive properties. Within the last three decades, chitosan and its derivatives have been investigated as biomaterials for drug and vaccine delivery systems, besides for their bioactive properties. Due to the functional groups in its structure, it is possible to tailor the delivery systems with desired properties. There has been a great interest in the application of chitosan-based systems also for the prevention and treatment of infectious diseases, specifically due to their antimicrobial, antiviral, and immunostimulatory effects. In this review, recent applications of chitosan in the prevention and treatment of infectious diseases are reviewed, and possibilities and limitations with regards to technical and regulatory aspects are discussed. Finally, the future perspectives on utilization of chitosan as a biomaterial are discussed.

SARS-CoV-2 Fusion Peptide Conjugated to a Tetravalent Dendrimer Selectively Inhibits Viral Infection

Fusion is a key event for enveloped viruses, through which viral and cell membranes come into close contact. This event is mediated by viral fusion proteins, which are divided into three structural and functional classes. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein belongs to class I fusion proteins, characterized by a trimer of helical hairpins and an internal fusion peptide (FP), which is exposed once fusion occurs. Many efforts have been directed at finding antivirals capable of interfering with the fusion mechanism, mainly by designing peptides on the two heptad-repeat regions present in class I viral fusion proteins. Here, we aimed to evaluate the anti-SARS-CoV-2 activity of the FP sequence conjugated to a tetravalent dendrimer through a classical organic nucleophilic substitution reaction (SN2) using a synthetic bromoacetylated peptide mimicking the FP and a branched scaffold of poly-L-Lysine functionalized with cysteine residues. We found that the FP peptide conjugated to the dendrimer, unlike the monomeric FP sequence, has virucidal activity by impairing the attachment of SARS-CoV-2 to cells. Furthermore, we found that the peptide dendrimer does not have the same effects on other coronaviruses, demonstrating that it is selective against SARS-CoV-2.