(541c) Interferon-Mediated Innate Immune Responses to Virus Infection

Vesicular Stomatitis Virus (VSV) is an important vaccine vector and also has potential applications as an oncolytic (tumor-killing) virus. Strains of VSV that stimulate a type I interferon (IFN) response are an important hallmark in the design of RNA-virus based therapeutic strategies. VSV wild type can shutdown its host innate immune response. VSV matrix (M) protein blocks the cellular antiviral response by interrupting the cellular transcription machinery and blockading nucleocytoplasmic mRNA transport through cellular nucleopore protein 98 (Nup98). Here, we used different VSV mutants in which the N gene, encoding the viral nucleocapside protein), was moved from its 3` promoter proximal position in the wild-type virus (N1), toward the 5` distal end, defining mutants N2, N3 and N4. We also studied M protein mutant (M51R) in which Methionine (M) 51 is converted to Arginine(A), where the mutation inactivates M-protein-mediated blocking of the cellular antiviral response. We found that VSV-N3 induced several genes involved in innate immune response with a similar profile to VSV-M51R; both strains induced the expression of key transcriptional factors like STAT1. In our global study of gene expression by RNA microarray, we observed broad patterns of differential gene expression that reflected differences in viral strains: genes 2 fold up regulated (N1≥1617, N2≥344, N3≥627, N4≥50, M51R≥891) and 2 fold down regulated (N1≥3839, N2≥223, N3≥558, N4≥46 and M51R≥741). VSV transcription is sequential process under the control of single 3` transcription initiation site, where polymerase enter and transcribe viral mRNAs as a gene order N>P>M>G>L. Surprisingly, the expression of VSV-G reflects a different pattern in all mutants (N>G>P>M>L),. These studies begin to highlight how subtle and not-so-subtle changes in the timing and level of viral gene expression can impact the pattern of host defensive responses.