Key result
Mutations in the seed sequence of the mivaRNAI duplex did not affect late viral protein synthesis or new virus progeny formation under lytic replicative conditions in HeLa or HEK293 cells.
The mivaRNAI duplex seed sequences are not essential for adenovirus lytic growth in tissue culture, whereas the suppressive effect of VA RNAI on the PKR pathway is critical for late gene expression.
mivaRNAI seed mutations spare adenovirus lytic growth in culture; leaves open essential roles in vivo or non-lytic settings.
At late times during a lytic infection human adenovirus type 5 produces ∼10(8) copies per cell of virus-associated RNA I (VA RNAI). This short highly structured RNA polymerase III transcript has previously been shown to be essential for lytic virus growth. A fraction of VA RNAI is processed by Dicer into small RNAs, so-called mivaRNAIs, which are efficiently incorporated into the RNA-induced silencing complex. Here, we constructed recombinant adenoviruses with mutations in the seed sequence of both the 5'- and the 3'-strand of the mivaRNAI duplex. The results showed that late viral protein synthesis, as well as new virus progeny formation, was essentially unaffected by the seed sequence mutations under lytic replicative conditions in HeLa or HEK293 cells. Collectively, our results suggest that either strand of the mivaRNAI duplex does not have target mRNA interactions that are critical for the establishment of virus growth under lytic conditions. Further, by depletion of protein kinase R (PKR) in HEK293 cells, we show that the suppressive effect of VA RNAI on the interferon-induced PKR pathway is most critical for late gene expression.
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Kamel et al. (2013) studied Human adenovirus type 5 lytic infection. Mutations in the seed sequence of the mivaRNAI duplex was evaluated on Late viral protein synthesis and new virus progeny formation. Mutations in the seed sequence of the mivaRNAI duplex did not affect late viral protein synthesis or new virus progeny formation under lytic replicative conditions in HeLa or HEK293 cells.
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