siRNA, miRNA and HIV: promises and challenges

Small interfering RNA (siRNA) and microRNA (miRNA) are small RNAs of 18-25 nucleotides (nt) in length that play important roles in regulating gene expression. They are incorporated into an RNA-induced silencing complex (RISC) and serve as guides for silencing their corresponding target mRNAs based on complementary base-pairing. The promise of gene silencing has led many researchers to consider siRNA as an anti-viral tool. However, in long-term settings, many viruses appear to escape from this therapeutical strategy. An example of this may be seen in the case of human immunodeficiency virus type-1 (HIV-1) which is able to evade RNA silencing by either mutating the siRNA- targeted sequence or by encoding for a partial suppressor of RNAi (RNA interference). On the other hand, because miRNA targeting does not require absolute complementarity of base-pairing, mutational escape by viruses from miRNA- specified silencing may be more difficult to achieve. In this review, we discuss stratagems used by various viruses to avoid the cells’ antiviral si/mi-RNA defenses and notions of how viruses might control and regulate host cell genes by encoding viral miRNAs (vmiRNAs).

Peptidic defective interfering gene nanoparticles against Omicron,Delta SARS-CoV-2 variants and influenza A virus in vivo

Defective interfering genes(DIGs)are short viral genomes and interfere with wild-type viral replication.Here,we demonstrate that the new designed SARS-CoV-2 DIG(CD3600)can significantly inhibit the replication of SARS-CoV-2 including Alpha,Delta,Kappa and Omicron variants in human HK-2 cells and influenza DIG(PAD4)can significantly inhibit influenza virus replication in human A549 cells.One dose of influenza DIGs prophylactically protects 90%mice from lethal challenge of A(H1N1)pdm09 virus and CD3600 inhibits SARS-CoV-2 replication in hamster lungs when DIGs are administrated to lungs one day before viral challenge.To further investigate the gene delivery vector in the respiratory tract,a peptidic TAT2-P1&LAH4,which can package genes to form small spherical nanoparticles with high endosomal escape ability,is demonstrated to dramatically increase gene expression in the lung airway.TAT2-P1&LAH4,with the dual-functional TAT2-P1(gene-delivery and antiviral),can deliver CD3600 to significantly inhibit the replication of Delta and Omicron SARS-CoV-2 in hamster lungs.This peptide-based nanoparticle system can effectively transfect genes in lungs and deliver DIGs to inhibit SARS-CoV-2 variants and influenza virus in vivo,which provides the new insight into the drug delivery system for gene therapy against respiratory viruses.