Periodic Reporting for period 4 - Profile Infection (Unraveling changes in cellular gene expression during viral infection)
Reporting period: 2019-12-01 to 2020-05-31
This allowed us to uncover multiple novel layers of cellular gene regulation that HCMV is utilizing to modulate the host cell. These findings enhance our understanding of this sophisticated pathogen, reveal general principles in cell biology and can help to facilitate the development of novel anti-viral strategies. Furthermore, our work revealed HCMV latency is mostly driven by the host cell environment and we have characterized cell surface markers that allow enrichment of latent cells as well as the changes that occur in cells during latency. These findings provide a potential new context for deciphering virus-host interactions underlying HCMV lifelong persistence and can provide novel means to identify latent cells to prevent reactivation and disease.
Although reactivation from latency causes serious disease in immunocompromised individuals, our molecular understanding of latency and ability to detect latent cells are still very limited. We utilized the power of single-cell RNA-seq (scRNA-seq) to unbiasedly examine the viral transcriptome in latency and made the ground-breaking observation that in latency there are mostly quantitative but not qualitative changes in viral gene expression (Shnayder et al. mBio, 2018). Furthermore, by exploiting the ability of scRNA-seq to tackle heterogeneity in infection level, we characterized specific changes that occur in cellular gene expression during latency. This analysis revealed that regardless of the differentiation state of the infected cells, HCMV latency drives cells towards an anergic-like monocyte state (Shnayder et al., eLife 2020).
With regard to full characterization of the latency state, one of the obstacles in studying HCMV latency is the heterogeneity in the cell culture models that are being used. We utilized the power of single-cell RNA-seq (scRNA-seq) to unbiasedly examine the viral transcriptome in latency and made the ground-breaking observation that in latency there are mostly quantitative but not qualitative changes in viral gene expression (Shnayder et al. mBio, 2018). This analysis emphasizes undeniable surprising similarity between latent and late lytic transcriptional programs. These results, together with additional analysis we conducted in natural samples, challenge the view of a well-defined HCMV latency-specific transcriptional program that is composed of few selective functional genes. Instead, these measurements raise the possibility of a gradual repression of viral gene expression resulting in low-level expression of a program that resembles late lytic infection stage.
a central withstanding question is- what are the molecular events leading to the viral transcriptional state during latency? We are currently conducting high temporal resolution measurements, at single cell level, of the early steps during latent and infection of different myeloid populations in order to shed light on the molecular events that lead to the wide but repressed viral gene expression in latent cells.