title: Inhibition of vaccinia virus replication by two small interfering RNAs targeting B1R and G7L genes and their synergistic combination with cidofovir.
abstract: In view of the threat of the potential use of variola virus in a terrorist attack, considerable efforts have been performed to develop new antiviral strategies against orthopoxviruses. Here we report on the use of RNA interference, either alone or in combination with cidofovir, as an approach to inhibit orthopoxvirus replication. Two selected small interfering RNAs (siRNAs), named siB1R-2 and siG7L-1, and a previously reported siRNA, i.e., siD5R-2 (which targets the viral D5R mRNA), were evaluated for antiviral activity against vaccinia virus (VACV) by plaque reduction and virus yield assays. siB1R-2 and siG7L-1, administered before or after viral infection, reduced VACV replication by more than 90%. Also, these two siRNAs decreased monkeypox virus replication by 95% at a concentration of 1 nM. siB1R-2 and siG7L-1 were demonstrated to specifically silence their corresponding transcripts, i.e., B1R and G7L mRNAs, without induction of a beta interferon response. Strong synergistic effects were observed when siB1R-2, siG7L-1, or siD5R-2 was combined with cidofovir. In addition, the antiviral activities of these three siRNAs were evaluated against VACV resistant to cidofovir and other acyclic nucleoside phosphonates. siG7L-1 and siD5R-2 remained active against four of five VACV mutants, while siB1R-2 showed activity against only one of the mutants. Our results showed that siRNAs are potent inhibitory agents in vitro, not only against wild-type VACV but also against several cidofovir-resistant VACV. Furthermore, we showed that a combined therapy using siRNA and cidofovir may be useful in the treatment of poxvirus infections.
authors.affiliation: Laboratoire de Virologie, CRSSA Emile Pardé, 24 Avenue des Maquis du Grésivaudan, 38702 La Tronche, France.
authors.forename: Solenne
authors.initials: S
authors.lastname: Vigne
authors.forename: Sophie
authors.initials: S
authors.lastname: Duraffour
authors.forename: Graciela
authors.initials: G
authors.lastname: Andrei
authors.forename: Robert
authors.initials: R
authors.lastname: Snoeck
authors.forename: Daniel
authors.initials: D
authors.lastname: Garin
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Crance
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D000077404:Cidofovir; D003596:Cytosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D063065:Organophosphonates / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000494:pharmacology*; D014616:Vaccinia virus / Q000187:drug effects*; D014758:Viral Core Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D014764:Viral Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D063065:Organophosphonates; D034741:RNA, Small Interfering; C074058:VB1R protein, Vaccinia virus; D014758:Viral Core Proteins; D014764:Viral Proteins; D007371:Interferon-gamma; D003596:Cytosine; D004259:DNA-Directed DNA Polymerase; D000077404:Cidofovir