Inhibition of enterovirus 71 infection by antisense octaguanidinium dendrimer-conjugated morpholino oligomers.
Enterovirus 71 (EV-71) infections are generally manifested as mild hand, foot and mouth disease, but have been reported to cause severe neurological complications with high mortality rates. Treatment options remain limited due to the lack of antivirals. Octaguanidinium-conjugated morpholino oligomers (vivo-MOs) are single-stranded DNA-like antisense agents that can readily penetrate cells and reduce gene expression by steric blocking of complementary RNA sequences. In this study, inhibitory effects of three vivo-MOs that are complementary to the EV-71 internal ribosome entry site (IRES) and the RNA-dependent RNA polymerase (RdRP) were tested in RD cells. Vivo-MO-1 and vivo-MO-2 targeting the EV-71 IRES showed significant viral plaque reductions of 2.5 and 3.5 log10PFU/ml, respectively. Both vivo-MOs reduced viral RNA copies and viral capsid expression in RD cells in a dose-dependent manner. In contrast, vivo-MO-3 targeting the EV-71 RdRP exhibited less antiviral activity. Both vivo-MO-1 and 2 remained active when administered either 4h before or within 6h after EV-71 infection. Vivo-MO-2 exhibited antiviral activities against poliovirus (PV) and coxsackievirus A16 but vivo-MO-1 showed no antiviral activities against PV. Both the IRES-targeting vivo-MO-1 and vivo-MO-2 inhibit EV-71 RNA translation. Resistant mutants arose after serial passages in the presence of vivo-MO-1, but none were isolated against vivo-MO-2. A single T to C substitution at nucleotide position 533 was sufficient to confer resistance to vivo-MO-1. Our findings suggest that IRES-targeting vivo-MOs are good antiviral candidates for treating early EV-71 infection, and vivo-MO-2 is a more favorable candidate with broader antiviral spectrum against enteroviruses and are refractory to antiviral resistance.
Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Chee Wah
CW
Tan
Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Tropical Infectious Disease Research and Education Center, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Yoke Fun
YF
Chan
Faculty of Science and Technology, Sunway University, 46150 Petaling Jaya, Selangor, Malaysia.
Yi Wan
YW
Quah
Faculty of Science and Technology, Sunway University, 46150 Petaling Jaya, Selangor, Malaysia. Electronic address: pohcl@sunway.edu.my.
Chit Laa
CL
Poh
D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D050091:Dendrimers / Q000494:pharmacology*; D024882:Drug Resistance, Viral; D004770:Enterovirus / Q000187:drug effects; D029821:Enterovirus A, Human / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D060172:Morpholinos / Q000494:pharmacology*; D017955:Poliovirus / Q000187:drug effects; D012692:Serial Passage; D010948:Viral Plaque Assay; D014779:Virus Replication / Q000187:drug effects*
D000998:Antiviral Agents; D050091:Dendrimers; D060172:Morpholinos
Antiviral agent; Enterovirus; Enterovirus 71; Hand, foot and mouth disease; Morpholino oligomers