Design and selection of peptides to block the SARS-CoV-2 receptor binding domain by molecular docking.

The novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is currently one of the most contagious viruses in existence and the cause of the worst pandemic in this century, COVID-19. SARS-CoV-2 infection begins with the recognition of the cellular receptor angiotensin converting enzyme-2 by its spike glycoprotein receptor-binding domain (RBD). Thus, the use of small peptides to neutralize the infective mechanism of SARS-CoV-2 through the RBD is an interesting strategy. The binding ability of 104 peptides (University of Nebraska Medical Center's Antimicrobial Peptide Database) to the RBD was assessed using molecular docking. Based on the molecular docking results, peptides with great affinity to the RBD were selected. The most common amino acids involved in the recognition of the RBD were identified to design novel peptides based on the number of hydrogen bonds that were formed. At physiological pH, these peptides are almost neutral and soluble in aqueous media. Interestingly, several peptides showed the capability to bind to the active surface area of the RBD of the Wuhan strain, as well as to the RBD of the Delta variant and other SARS-Cov-2 variants. Therefore, these peptides have promising potential in the treatment of the COVID-19 disease caused by different variants of SARS-CoV-2. This research work will be focused on the molecular docking of peptides by molecular dynamics, in addition to an analysis of the possible interaction of these peptides with physiological proteins. This methodology could be extended to design peptides that are active against other viruses.

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV.

The white spot syndrome virus (WSSV), currently affecting cultured shrimp, causes substantial economic losses to the worldwide shrimp industry. An antiviral therapy using double-stranded RNA interference (dsRNAi) by intramuscular injection (IM) has proven the most effective shrimp protection against WSSV. However, IM treatment is still not viable for shrimp farms. The challenge is to develop an efficient oral delivery system that manages to avoid the degradation of antiviral RNA molecules. The present work demonstrates that VLPs (virus-like particles) allow efficient delivery of dsRNAi as antiviral therapy in shrimp. In particular, VLPs derived from a virus that infects plants, such as cowpea chlorotic mottle virus (CCMV), in which the capsid protein (CP) encapsidates the dsRNA of 563 bp, are shown to silence the WSSV glycoprotein VP28 (dsRNAvp28). In experimental challenges in vivo, the VLPs- dsRNAvp28 protect shrimp against WSSV up to 40% by oral administration and 100% by IM. The novel research demonstrates that plant VLPs, which avoid zoonosis, can be applied to pathogen control in shrimp and also other organisms, widening the application window in nanomedicine.

Brome mosaic virus-like particles as siRNA nanocarriers for biomedical purposes.

There is an increasing interest in the use of plant viruses as vehicles for anti-cancer therapy. In particular, the plant virus brome mosaic virus (BMV) and cowpea chlorotic mottle virus (CCMV) are novel potential nanocarriers for different therapies in nanomedicine. In this work, BMV and CCMV were loaded with a fluorophore and assayed on breast tumor cells. The viruses BMV and CCMV were internalized into breast tumor cells. Both viruses, BMV and CCMV, did not show cytotoxic effects on tumor cells in vitro. However, only BMV did not activate macrophages in vitro. This suggests that BMV is less immunogenic and may be a potential carrier for therapy delivery in tumor cells. Furthermore, BMV virus-like particles (VLPs) were efficiently loaded with small interfering RNA (siRNA) without packaging signal. The gene silencing was demonstrated by VLPs loaded with siGFP and tested on breast tumor cells that constitutively express the green fluorescent protein (GPF). After VLP-siGFP treatment, GFP expression was efficiently inhibited corroborating the cargo release inside tumor cells and the gene silencing. In addition, BMV VLP carring siAkt1 inhibited the tumor growth in mice. These results show the attractive potential of plant virus VLPs to deliver molecular therapy to tumor cells with low immunogenic response.

CD43 promotes cells transformation by preventing merlin-mediated contact inhibition of growth.

In normal tissues, strict control of tissue size is achieved by regulating cell numbers. The mechanism that controls total cell number is known as contact inhibition of growth and it depends on the NF2/Merlin pathway. Negative regulation of this pathway by deleterious mutations or by oncogenes results in cell transformation and tumor progression. Here we provide evidence that the CD43 sialomucin cooperates with oncogenic signals to promote cell transformation by abrogating the contact inhibition of growth through a molecular mechanism that involves AKT-dependent Merlin phosphorylation and degradation. Accordingly, inhibition of endogenous CD43 expression by RNA interference in lung, cervix and colon human cancer cells impaired tumor growth in vivo. These data underscore a previously unidentified role for CD43 in non-hematopoietic tumor progression.