Virus microRNAs
MicroRNAs (miRNAs) are a class of small (~21–25 nucleotides) single-stranded RNAs that can inhibit the expression of specific messenger RNAs by binding to complementary target sequences within the mRNAs. Given the propensity of viruses to co-opt cellular pathways and activities for their benefit, it is perhaps not surprising that several viruses have now been shown to reshape the cellular environment by reprogramming the host’s RNA-interference machinery. In particular, microRNAs are produced by the various members of the herpesvirus family during both the latent stage of the viral life cycle and the lytic (or productive) stage. Emerging data suggest that viral microRNAs are particularly important for regulating the transition from latent to lytic replication and for attenuating antiviral immune responses.
At present, there is no evidence that any vertebrate virus encodes novel miRNA-processing factors or RISC components. So it seems that, in general, viral miRNAs are transcribed and processed in the same way as cellular miRNAs. Despite our still limited knowledge of viral miRNA functions, the large number of miRNAs that are encoded by diverse members of the herpesvirus family, and their high-level expression during latent infections, suggests that these small non-coding RNAs have a key role in regulating viral pathogenesis in vivo. In particular, it will be important to test the hypothesis that herpesvirus miRNAs that are produced during latency help to maintain the latent state, which could be examined by using viral mutants and/or antisense reagents. It certainly seems possible that antisense reagents specific for particular viral miRNAs could significantly attenuate herpesvirus-induced diseases in humans, if they could be delivered effectively to infected cells in vivo – like this!
Viral and cellular messenger RNA targets of viral microRNAs. 2009 Nature 457, 421-425
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Tags: Biology, Biotechnology, Health, Medicine, Microbiology, Science, Virology
One such antisense RNA based therapy is Ganciclovir (foscarnet), approved for use in cytomegalovirus (CMV) retinitis. The antisense strand latches to the mRNA and interferes with translation, making it useless.
No Amiya, Ganciclovir is not an antisense RNA therapy, it is a conventional drug which inhibits cytomegalovirus thymidine kinase.