Search

Abstract: The genus Alphavirus contains members that threaten human health, both as natural pathogens and as potential biological weapons. Peptide-conjugated phosphorodiamidate morpholino oligomers (PPMO) enter cells readily and can inhibit viral replication through sequence-specific steric blockade of viral RNA. Sindbis virus (SINV) has low pathogenicity in humans and is regularly utilized as a model alphavirus. PPMO targeting the 5′-terminal and AUG translation start site regions of the SINV genome blocked the production of infectious SINV in tissue culture. PPMO designed against corresponding regions in Venezuelan equine encephalitis virus (VEEV) were likewise found to be effective in vitro against several strains of VEEV. Mice treated with PPMO before and after VEEV infection were completely protected from lethal outcome while mice receiving only post-infection PPMO treatment were partially protected. Levels of virus in tissue samples correlated with animal survival. Uninfected mice suffered no apparent ill-effects from PPMO treatment. Thus, PPMO appear promising as candidates for therapeutic development against alphaviruses. [Copyright &y& Elsevier]

Abstract: West Nile virus (WNV) genome cyclization and replication require two pairs of long-distance RNA interactions. Besides the previously reported 5′CS/3′CSI (conserved sequence) interaction, a 5′UAR/3′UAR (upstream AUG region) interaction also contributes to genome cyclization and replication. WNVs containing mutant 5′UARs capable of forming the 5′/3′ viral RNA interaction were replicative. In contrast, WNV containing a 5′UAR mutation that abolished the 5′/3′ viral RNA interaction was non-replicative; however, the replication defect could be rescued by a single-nucleotide adaptation that restored the 5′/3′ RNA interaction. The 5′UAR/3′UAR interaction is critical for RNA synthesis, but not for viral translation. Antisense oligomers targeting the 5′UAR/3′UAR interaction effectively inhibited WNV replication. Phylogenic analysis showed that the 3′UAR could alternate between pairing with the 5′UAR or with the 3′ end of the flaviviral genome. Therefore, the 5′UAR/3′UAR pairing may release the 3′ end of viral genome (as a template) during the initiation of minus-strand RNA synthesis. [Copyright &y& Elsevier]