Prospects for RNAi Therapy of COVID-19

Abstract

COVID-19 caused by the SARS-CoV-2 virus is a fast emerging disease with deadly consequences. The pulmonary system and lungs in particular are most prone to damage caused by the SARS-CoV-2 infection, which leaves a destructive footprint in the lung tissue, making it incapable of conducting its respiratory functions and resulting in severe acute respiratory disease and loss of life. There were no drug treatments or vaccines approved for SARS-CoV-2 at the onset of pandemic, necessitating an urgent need to develop effective therapeutics. To this end, the innate RNA interference (RNAi) mechanism can be employed to develop front line therapies against the virus. This approach allows specific binding and silencing of therapeutic targets by using short interfering RNA (siRNA) and short hairpin RNA (shRNA) molecules. In this review, we lay out the prospect of the RNAi technology for combatting the COVID-19. We first summarize current understanding of SARS-CoV-2 virology and the host response to viral entry and duplication, with the purpose of revealing effective RNAi targets. We then summarize the past experience with nucleic acid silencers for SARS-CoV, the predecessor for current SARS-CoV-2. Efforts targeting specific protein-coding regions within the viral genome and intragenomic targets are summarized. Emphasizing non-viral delivery approaches, molecular underpinnings of design of RNAi agents are summarized with comparative analysis of various systems used in the past. Promising viral targets as well as host factors are summarized, and the possibility of modulating the immune system are presented for more effective therapies. We place special emphasis on the limitations of past studies to propel the field faster by focusing on most relevant models to translate the promising agents to a clinical setting. Given the urgency to address lung failure in COVID-19, we summarize the feasibility of delivering promising therapies by the inhalational route, with the expectation that this route will provide the most effective intervention to halt viral spread. We conclude with the authors’ perspectives on the future of RNAi therapeutics for combatting SARS-CoV-2. Since time is of the essence, a strong perspective for the path to most effective therapeutic approaches are clearly articulated by the authors.

Potential approaches to combat COVID-19: a mini-review

“…Moreover, possibility stands that lasting immunization may not entirely develop in few people. RNAi therapy can act as a substitute when an unintended vaccination consequence arises [3].…”

“…For RNAi-provoked silencing, few of the accessory proteins (such as non-structural protein 15 (nsp15) that displays anti-apoptotic role through inhibition of apoptosis induced by MAVS [3,56]; ORF-3a, ORF-4a that might play a role of ion channel which might trigger release of virus [3,57] and ORF-9b that is involved in manipulation of mitochondria which resists responses of IFN [3,58]) encoded by SARS-CoV can function as targets. The significance of the aforementioned potential targets still needs to be probed.…”

“…These miRs might behave as targets for RNAi. They could be directly employed (whether as anti-miRs or mimics of miR), or indirectly in consequence to pharmacological entity regulation [3].…”

“…It is apparent that SARS-CoV-2 gains its access inside the cell through an enzyme that is amply expressed on the surface of the cell termed as ACE2 (Angiotensinconverting enzyme 2). Against certain critical organs such as lungs, gastrointestinal tract, kidneys and airways, SARS-CoV-2 exhibits potent tropism [3].…”

“…Additional significant pathologies were noticed, in particular clotting ailment, failure of liver and kidney and nervous system disorder. Their criticality and implications lately have been started to be apprehended [3].…”