CNBP restricts SARS-CoV2 by regulating IFN and disrupting RNA-protein condensates

Sensing nucleotide composition in virus RNA

Nucleotide composition plays a crucial role in the structure, function and recognition of RNA molecules. During infection, virus RNA is exposed to multiple endogenous proteins that detect local or global compositional biases and interfere with virus replication. Recent advancements in RNA:protein mapping technologies have enabled the identification of general RNA-binding preferences in the human proteome at basal level and in the context of virus infection. In this review, we explore how cellular proteins recognise nucleotide composition in virus RNA and the impact these interactions have on virus replication. Protein-binding G-rich and C-rich sequences are common examples of how host factors detect and limit infection, and, in contrast, viruses may have evolved to purge their genomes from such motifs. We also give examples of how human RNA-binding proteins inhibit virus replication, not only by destabilising virus RNA, but also by interfering with viral protein translation and genome encapsidation. Understanding the interplay between cellular proteins and virus RNA composition can provide insights into host-virus interactions and uncover potential targets for antiviral strategies.

Molecular mechanisms and cellular functions of liquid-liquid phase separation during antiviral immune responses

Spatiotemporal separation of cellular components is vital to ensure biochemical processes. Membrane-bound organelles such as mitochondria and nuclei play a major role in isolating intracellular components, while membraneless organelles (MLOs) are accumulatively uncovered via liquid-liquid phase separation (LLPS) to mediate cellular spatiotemporal organization. MLOs orchestrate various key cellular processes, including protein localization, supramolecular assembly, gene expression, and signal transduction. During viral infection, LLPS not only participates in viral replication but also contributes to host antiviral immune responses. Therefore, a more comprehensive understanding of the roles of LLPS in virus infection may open up new avenues for treating viral infectious diseases. In this review, we focus on the antiviral defense mechanisms of LLPS in innate immunity and discuss the involvement of LLPS during viral replication and immune evasion escape, as well as the strategy of targeting LLPS to treat viral infectious diseases.

Considering innate immune responses in SARS-CoV-2 infection and COVID-19

During the COVID-19 pandemic, much of the media focus has been on adaptive immunity, particularly antibody levels and memory T cells. However, immunologists have been striving to decipher how SARS-CoV-2 infection impacts our first line of defence, namely the innate immune system. In early 2022, Program staff from the NIAID at the NIH organized a workshop focusing on the innate immune response to SARS-CoV-2 infection and during COVID-19, which was chaired by Ralph Baric, Jenny Ting and John Lambris. Following the meeting, Nature Reviews Immunology invited some of the organizers and speakers to share their thoughts on the key discussion points.