Viral Condensates and Virus Interference with Host Membraneless Organelles

Dear Colleagues,

Intrinsically disordered proteins (IDPs) or regions (IDRs) are ubiquitous functional proteins/regions devoid of stable secondary and tertiary structure. Compelling experimental evidence gathered during the last decade points to a critical role for IDPs/IDRs, either alone or in conjunction with nucleic acids, in promoting liquid–liquid phase separation (LLPS). LLPS is a physicochemical process whereby an initially homogenous solution turns into two distinct phases—a “dense” phase that contains the major portion of the dissolved macromolecules, and a “light” phase containing the solvent. LLPS is not merely an in vitro process. Rather, it also occurs in the cellular context, where it drives the formation of so-called membrane-less organelles (MLOs) (e.g., nucleoli, nuclear speckles, Cajal bodies, processing bodies, stress granules, aggresomes, centrosomes, etc). MLOs are supramolecular assemblies possessing regulatory, structural, and enzymatic functions. They are responsible for the spatial and temporal organization of the cell and play a crucial role in a number of physiological processes. Liquid biocondensates resulting from LLPS can also undergo “maturation”, developing into gelled and/or solid-like forms that can eventually nucleate amyloid-like fibrils. Protein aggregation into amyloid fibrils is the archetype of aberrant biomolecular self-assembly processes associated with uncurable neurodegenerative diseases. Likewise, phase transitions from liquid to solid are mostly associated with pathological states.

The phenomenon of LLPS is also exploited by viruses. Viruses take advantage of LLPS for their replication either by interfering with (dis)assembly and regulation of host MLOs or by eliciting the formation of viral factories, i.e., condensates made of their own proteins either alone or in association with nucleic acids. Such viral inclusions are sites where viral replication and assembly take place and where specific viral and cellular proteins, along with nucleic acids, concentrate. They serve as platforms for optimized viral replication and/or assembly via selective uptake or exclusion of specific cellular components and shielding from the host immune defense. So far, the majority of studies have focused on LLPS in relation with replication compartments, and few studies have described interference with host functions. Likewise, only a few studies have focused on the functional impact of phase transitions towards gelled and/or fibrillar states of viral condensates. Examples of fibrils made of viral proteins have just begun to be reported, and the possible implications for pathogenesis are just starting to be discussed.

This Special Issue aims at filling this gap by collecting contributions that cover different aspects of viral condensate formation with an emphasis on new promising antiviral approaches that target these processes.

Dr. Sonia Longhi
Dr. Marie Galloux
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.