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Ectromelia virus accumulates less double-stranded RNA compared to vaccinia virus in BS-C-1 cells.

ABSTRACT: Most orthopoxviruses, including vaccinia virus (VACV), contain genes in the E3L and K3L families. The protein products of these genes have been shown to combat PKR, a host defense pathway. Interestingly, ectromelia virus (ECTV) contains an E3L ortholog but does not possess an intact K3L gene. Here, we gained insight into how ECTV can still efficiently evade PKR despite lacking K3L. Relative to VACV, we found that ECTV-infected BS-C-1 cells accumulated considerably less double-stranded (ds) RNA, which was due to lower mRNA levels and less transcriptional read-through of some genes by ECTV. The abundance of dsRNA in VACV-infected cells, detected using a monoclonal antibody, was able to activate the RNase L pathway at late time points post-infection. Historically, the study of transcription by orthopoxviruses has largely focused on VACV as a model. Our data suggest that there could be more to learn by studying other members of this genus.

SUBMITTER: Frey TR

PROVIDER: S-EPMC5541908 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Ectromelia virus accumulates less double-stranded RNA compared to vaccinia virus in BS-C-1 cells.

Frey Tiffany R TR Lehmann Michael H MH Ryan Colton M CM Pizzorno Marie C MC Sutter Gerd G Hersperger Adam R AR

Virology 20170901

Most orthopoxviruses, including vaccinia virus (VACV), contain genes in the E3L and K3L families. The protein products of these genes have been shown to combat PKR, a host defense pathway. Interestingly, ectromelia virus (ECTV) contains an E3L ortholog but does not possess an intact K3L gene. Here, we gained insight into how ECTV can still efficiently evade PKR despite lacking K3L. Relative to VACV, we found that ECTV-infected BS-C-1 cells accumulated considerably less double-stranded (ds) RNA, ...[more]

PMID: 28628829

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Project description:Vaccinia virus has recently been used as an expression vector for gene delivery and an oncolytic agent for cancer therapy. Although it has been established that interferon-induced double-stranded RNA (dsRNA)-activated protein kinase (PKR) and RNase L interfere with viral replication, little else is known about the other host factors that might affect viral replication and virus-mediated host cell killing. In this study, we evaluated the roles of c-Jun NH2-terminal kinase (JNK) in oncolytic vaccinia virus replication and vaccinia virus-mediated host cell killing. We found that JNK knockout mouse embryonic fibroblasts (MEFs) were more susceptible to oncolytic vaccinia virus infection than wild-type MEFs. Moreover, viral replication and the production of infectious viral progeny were up to 100-fold greater in JNK-deficient MEFs than in wild-type MEFs. A similar result was observed for wild-type vaccinia virus. The increased killing of infected cells and the production of viral progeny was also observed in wild-type MEFs that had been treated with JNK inhibitors and in human colon cancer cells that had been transfected with dominant-negative JNK constructs. Moreover, testing on several human lung cancer cell lines and HeLa cells showed an inverse correlation between levels of JNK expression and susceptibility to oncolytic vaccinia virus. Our study also revealed that oncolytic virus infection-mediated PKR activation was blocked or diminished in JNK-deficient MEFs. The adenovirus-mediated ectopic expression of human PKR in JNK-deficient MEFs reduced vaccinia virus replication to the levels observed in wild-type MEFs, indicating that JNK is required for vaccinia virus to efficiently activate PKR. Our results demonstrated that the cellular status of JNK function can dramatically affect oncolytic vaccinia virus replication and vaccinia virus-mediated host cell killing. This finding may enable further improvements in oncolytic virotherapy using vaccinia virus.

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Ectromelia virus accumulates less double-stranded RNA compared to vaccinia virus in BS-C-1 cells.

Publications

Ectromelia virus accumulates less double-stranded RNA compared to vaccinia virus in BS-C-1 cells.

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