Molecular Basis of Cancer Virus Replication, Transformation, and Innate Defense

冠状病毒病(新冠肺炎)及其病原体严重急性呼吸综合征冠状病毒2型(SARS-CoV-2)是目前最紧迫的健康问题。需要更多地了解病毒的病理以及宿主对病毒感染的反应。急性呼吸窘迫综合征是严重新冠肺炎的最终状态，是由宿主的免疫反应失控引起的，即所谓的细胞因子释放综合征。目前尚不清楚是什么促使一些患者进展为严重新冠肺炎，但某些人群--如老年人和癌症患者--风险更高。因此，我们正在研究宿主微RNA(MiRNAs)能否作为新冠肺炎预后的生物标志物。由于miRNAs几乎控制着每一个细胞过程，在疾病期间，包括病毒感染期间，往往是不受调控的，因此SARS-CoV-2感染极有可能影响miRNA水平。已知病毒感染过程中异常的miRNA图谱既是由宿主对侵染剂的中和反应引起的，也是由病毒的故意行为引起的，通常是为了抑制免疫系统。我们的团队在认识到一些疱疹病毒转录本选择性地结合宿主miRNA并诱导其降解的过程中做出了重要贡献，这一过程被称为靶向miRNA降解(TDMD)。这种选择性的miRNA降解对病毒有利，宿主miR 27A水平的降低就是例证，它会导致T细胞的长期激活，从而帮助疱疹病毒saimiri进行致癌转化。SARS-CoV-2可能选择性地影响调节关键细胞因子的miRNAs，因为许多已知的miRNAs调节参与抗病毒防御的免疫因素。其中之一是严重COVID19期间的关键角色：白介素6(IL-6)，受miR-146a、miR-142-3p和let-7调节。因此，记录SARS-CoV-2感染过程中特定miRNAs的失调可能具有治疗潜力，并为COVID的进展提供生物标志物。我们将使用最新的小RNA测序技术，以及TaqMan反转录定量聚合酶链式反应(RT-qPCR)对RNA的检测来研究SARS-CoV-2感染几种肺细胞系后不同时间的miRNA群体。此外，我们正在使用定制的生物信息学预测来搜索可以选择性地调节宿主miRNAs的病毒转录本，并已经确定了几个潜在的候选基因。提供有关这些重要宿主非编码RNA的SARS-CoV-2生物学的基本见解，对于人类管理当前和未来大流行的能力将是重要的。

Coronavirus disease (COVID-19) and its causative agent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are currently a most pressing health concern. Much more needs to be learned about the pathology of the virus, as well as the host response to viral infection. Acute respiratory distress syndrome (ARDS), the final state of severe COVID-19, is caused by the uncontrollable immune response of the host, so called cytokine release syndrome (CRS). What predisposes some patients to progress to severe COVID-19 is not known, but certain populations – such as the elderly and cancer patients – are at higher risk. Therefore, we are investigating whether host microRNAs (miRNAs) can serve as biomarkers for COVID-19 prognosis. Since miRNAs regulate virtually every cellular process, and are often dysregulated during disease, including viral infections, it is highly likely that SARS-CoV-2 infection impacts miRNA levels. Aberrant miRNA profiles during viral infection are known to be caused both by host responses to counteract the infecting agent and by deliberate actions of the virus, usually to dampen the immune system Our group has contributed significantly to the realization that some herpesviral transcripts selectively bind host miRNAs and induce their degradation in a process known as target-directed miRNA degradation (TDMD). Such selective miRNA degradation is beneficial for the virus, as exemplified by decreased levels of host miR 27a causing prolonged T cell activation that aids oncogenic transformation by herpesvirus saimiri. It is possible that SARS-CoV-2 selectively affects the miRNAs that regulate crucial cytokines, as many miRNAs are known to regulate immune factors involved in antiviral defense. One of these is a key player during severe COVID19: interleukin 6 (IL-6), which is regulated by miR-146a, miR-142-3p and let-7. Documenting the dysregulation of particular miRNAs during infection by SARS-CoV-2 can therefore have therapeutic potential, as well as providing biomarkers for COVID progression. We will use state-of-the art small RNA sequencing, as well as RNA detection by TaqMan reverse transcription quantitative PCR (RT-qPCR) to investigate miRNA populations at various times after infection of several lung cell lines with SARS-CoV-2. In addition, we are employing custom bioinformatic predictions to search for viral transcripts that could selectively regulate host miRNAs and have already identified several potential candidates. Providing fundamental insights into the biology of SARS-CoV-2 as regards these important host noncoding RNAs will be important for mankind’s ability to manage both the current and future pandemics.