Immunological interactions in helminths-SARS CoV-2 coinfection: Could old enemy be a friend today?

Helminths are metazoan parasites affecting about one third of the worldwide population. Chronic helminth infections (CHIs) confer immunological tolerance to harmless and self-antigens mediated by regulatory T cells (Treg) that are up-regulated. In coronavirus disease 2019 (COVID-19), abnormal adaptive immune response and unrestrained innate immune response could result in local and systemic immune-mediated tissue damage. COVID-19 and CHIs establish complicated immune interactions due to SARS-CoV-2-induced immunological stimulation and CHIs-induced immunological tolerance. However, COVID-19 severity in patients with CHIs is mild, as immuno-suppressive anti-inflammatory cytokines counterbalance the risk of cytokine storm. Here, an overview of the interplay between helminths and COVID-19 severity is given. CHIs through helminth-derived molecules may suppress SARS-CoV-2 entry and associated hyperinflammation through attenuation of the TLR4/NF-kB signalling pathway. In addition, CHIs may reduce the COVID-19 severity by reducing the SARS-CoV-2 entry points at ACE2/DPP4/CD147 axis in the initial phase and immunomodulation in the late phase of the disease by suppressing TLR4/NF-kB signalling pathway.

The Breadth of Bacteriophages Contributing to the Development of the Phage-Based Vaccines for COVID-19: An Ideal Platform to Design the Multiplex Vaccine.

Phages are highly ubiquitous biological agents, which means they are ideal tools for molecular biology and recombinant DNA technology. The development of a phage display technology was a turning point in the design of phage-based vaccines. Phages are now recognized as universal adjuvant-free nanovaccine platforms. Phages are well-suited for vaccine design owing to their high stability in harsh conditions and simple and inexpensive large-scale production. The aim of this review is to summarize the overall breadth of the antiviral therapeutic perspective of phages contributing to the development of phage-based vaccines for COVID-19. We show that phage vaccines induce a strong and specific humoral response by targeted phage particles carrying the epitopes of SARS-CoV-2. Further, the engineering of the T4 bacteriophage by CRISPR (clustered regularly interspaced short palindromic repeats) presents phage vaccines as a valuable platform with potential capabilities of genetic plasticity, intrinsic immunogenicity, and stability.