Viral lncRNA: A regulatory molecule for controlling virus life cycle

Wang, Ziqiang; Zhao, Yiwan; Zhang, Yaou

Additionally, some non-coding genes can act as bi-functional factors to promote viral entry or the maintenance of a latent state. The non-coding gene Pag1 blocks the HzNV-1 gene hhi to establish viral latency by encoding two miRNAs that target and degrade the hhi1 transcript, which is a stimulator of apoptosis [29, 30] . PAT1, which is another non-coding transcript encoded by pag1, has also been verified to be involved in persistent infection in cells. However, whether PAT1 is directly responsible for the establishment of persistent infection or only enhances this process is unknown [31] . For HSV-1, the latency-associated non-coding transcript (LAT) is the only viral gene that is expressed during latent infection in neurons. In these cells, LAT exerts its anti-apoptotic effect [32] and blocks the function of early genes to maintain latency by proceeding into and functioning as a microRNA (miR-LAT) that down-regulates transforming growth factor-beta 1 and SMAD3 expression [33] . Moreover, adenovirus virus-associated RNAs (VA RNAs) are processed into small RNAs that are expressed at high levels and may be associated with the ability of this virus to efficiently establish a persistent infection [34] . One VA RNA-derived small RNAs (mivaRNA), mivaRNAI-138 can inhibit cell apoptosis by targeting and binding TIA-1, which is a well-characterized factor that activates apoptosis [35, 36] . Importantly, mRNAs associated with viral replication are essentially unaffected by these small noncoding RNAs [37] .