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

冠状病毒病（COVID-19）及其病原体严重急性呼吸综合征冠状病毒2 （SARS-CoV-2）是目前最紧迫的健康问题。关于这种病毒的病理学，以及宿主对病毒感染的反应，还需要了解更多。急性呼吸窘迫综合征（Acute respiratory distress syndrome， ARDS）是COVID-19重症患者的最终状态，是由宿主不可控的免疫反应引起的，称为细胞因子释放综合征（cytokine release syndrome， CRS）。目前尚不清楚是什么导致一些患者发展为严重的COVID-19，但某些人群（如老年人和癌症患者）的风险更高。因此，我们正在研究宿主microRNAs （miRNAs）是否可以作为COVID-19预后的生物标志物。由于miRNA几乎调节所有细胞过程，并且在疾病期间（包括病毒感染）经常失调，因此SARS-CoV-2感染极有可能影响miRNA水平。在病毒感染期间，异常的miRNA谱已知是由宿主对抗感染因子的反应和病毒的故意行为引起的，通常是为了抑制免疫系统。我们的研究小组在认识到一些疱疹病毒转录物选择性地结合宿主miRNA并诱导其降解的过程中做出了重大贡献，这一过程被称为靶向miRNA降解（TDMD）。这种选择性miRNA降解对病毒是有益的，例如，宿主miR 27a水平的降低导致T细胞激活时间延长，从而有助于猴疱疹病毒的致癌转化。SARS-CoV-2可能选择性地影响调节关键细胞因子的mirna，因为已知许多mirna调节参与抗病毒防御的免疫因子。其中一种是严重covid - 19期间的关键参与者：白细胞介素6 (IL-6)，它由miR-146a、miR-142-3p和let-7调节。因此，记录SARS-CoV-2感染期间特定mirna的失调可能具有治疗潜力，并为COVID的进展提供生物标志物。我们将使用最先进的小RNA测序以及TaqMan反转录定量PCR （RT-qPCR）的RNA检测来研究几种肺细胞系感染SARS-CoV-2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调节宿主mirna的病毒转录本，并已经确定了几个潜在的候选病毒转录本。就这些重要的宿主非编码rna提供对SARS-CoV-2生物学的基本见解，对人类管理当前和未来大流行的能力至关重要。

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.