Silencing of SARS-CoV-2 with modified siRNA-peptide dendrimer formulation.

BACKGROUND: First vaccines for prevention of Coronavirus disease 2019 (COVID-19) are becoming available but there is a huge and unmet need for specific forms of treatment. In this study we aimed to evaluate the anti-SARS-CoV-2 effect of siRNA both in vitro and in vivo. METHODS: To identify the most effective molecule out of a panel of 15 in silico designed siRNAs, an in vitro screening system based on vectors expressing SARS-CoV-2 genes fused with the firefly luciferase reporter gene and SARS-CoV-2-infected cells was used. The most potent siRNA, siR-7, was modified by Locked nucleic acids (LNAs) to obtain siR-7-EM with increased stability and was formulated with the peptide dendrimer KK-46 for enhancing cellular uptake to allow topical application by inhalation of the final formulation - siR-7-EM/KK-46. Using the Syrian Hamster model for SARS-CoV-2 infection the antiviral capacity of siR-7-EM/KK-46 complex was evaluated. RESULTS: We identified the siRNA, siR-7, targeting SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) as the most efficient siRNA inhibiting viral replication in vitro. Moreover, we showed that LNA-modification and complexation with the designed peptide dendrimer enhanced the antiviral capacity of siR-7 in vitro. We demonstrated significant reduction of virus titer and lung inflammation in animals exposed to inhalation of siR-7-EM/KK-46 in vivo. CONCLUSIONS: Thus, we developed a therapeutic strategy for COVID-19 based on inhalation of a modified siRNA-peptide dendrimer formulation. The developed medication is intended for inhalation treatment of COVID-19 patients.

Mucosal epithelial cells and novel approaches to immunoprophylaxy and immunotherapy of infectious diseases

Innate immune defense mechanisms activated by pathogen recognition can be roughly divided into two categories: 1) those aimed at direct killing of the pathogen (microbicidal);2) those aimed at the development of inflammation (pro-inflammatory). The final goal of both types of mechanisms is elimination of the pathogen and restoration of homeostasis. However, inflammation is accompanied by damage of self tissues, which often has a negative impact on the outcome of infection. Therefore, there is a need in such approaches to immunoprophylaxy and immunotherapy of infections that would enhance antimicrobial defense while minimizing inflammation. A key approach is elevation of epithelial barrier resistance. The proposed concept of immunostimulation is exemplified using COVID-19 infection. Защитные механизмы врожденной иммунной системы, активируемые в ответ на распознавание патогена, можно условно разделить на две категории: 1) направленные на непосредственное уничтожение патогена (микробицидные);2) направленные на развитие воспаления (провоспалительные). И те, и другие имеют целью элиминацию возбудителя и восстановление постоянства внутренней среды организма. Однако воспаление сопровождается повреждением собственных тканей, что во многих случаях негативно сказывается на исходе инфекционного процесса. Поэтому необходимы такие подходы к иммунопрофилактике и иммунотерапии инфекций, которые обеспечивали бы усиление антимикробной защиты при минимизации воспаления. Одним из основных способов решения этой задачи является повышение резистентности эпителиальных барьеров. Предлагаемая концепция иммуностимуляции рассматривается на примере инфекции COVID-19.