Convergent evolution in nucleocapsid facilitated SARS-CoV-2 adaptation for human infection.

During the early stages of the COVID-19 pandemic, several SARS-CoV-2 variants of concern (VOCs) independently acquired mutations in the highly variable 203-205 amino acid region of the nucleocapsid (N) protein including R203K + G204R (found in the Alpha, Gamma, and Omicron variants), R203M (in Delta), and T205I (in Beta). In previous research, we demonstrated that the R203K + G204R mutation significantly enhances SARS-CoV-2 N phosphorylation, which subsequently increases viral fitness and pathogenesis. In this study, we investigated the effects of the R203M and T205I mutations on SARS-CoV-2 infection.

The furin cleavage site is required for pathogenesis, but not transmission, of SARS-CoV-2.

Unlabelled: The SARS-CoV-2 spike, key to viral entry, has two features that differentiate it from other sarbecoviruses: the presence of a furin cleavage site (FCS; PRRAR sequence) and an extended S1/S2 loop characterized by an upstream QTQTN amino acid motif. Our prior works show that shortening the S1/S2 loop by deleting either the FCS (ΔPRRA) or an upstream sequence (ΔQTQTN) ablates spike processing, alters host protease usage, and attenuates infection and . With the importance of the loop length established, we evaluated the impact of disrupting the FCS while preserving the S1/S2 loop length.

Variant mutation G215C in SARS-CoV-2 nucleocapsid enhances viral infection via altered genomic encapsidation.

The evolution of SARS-CoV-2 variants and their respective phenotypes represents an important set of tools to understand basic coronavirus biology as well as the public health implications of individual mutations in variants of concern. While mutations outside of spike are not well studied, the entire viral genome is undergoing evolutionary selection, with several variants containing mutations in the central disordered linker region of the nucleocapsid (N) protein. Here, we identify a mutation (G215C), characteristic of the Delta variant, that introduces a novel cysteine into this linker domain, which results in the formation of a more stable N-N dimer.

The furin cleavage site is required for pathogenesis, but not transmission of SARS-CoV-2.

The SARS-CoV-2 spike, key to viral entry, has two features that differentiate it from other sarbecoviruses: the presence of a furin cleavage site (FCS; PRRAR sequence) and an extended S1/S2 loop characterized by an upstream QTQTN amino acid motif. Our prior works show that shortening the S1/S2 loop by deleting either the FCS (ΔPRRA) or deleting an upstream sequence (ΔQTQTN), ablates spike processing, alters host protease usage, and attenuates infection and . With the importance of the loop length established, here we evaluated the impact of disrupting the FCS, but preserving the S1/S2 loop length.

SARS-CoV-2 EndoU-ribonuclease regulates RNA recombination and impacts viral fitness.

Coronaviruses (CoVs) maintain large RNA genomes that frequently undergoes mutations and recombination, contributing to their evolution and emergence. In this study, we find that SARS-CoV-2 has greater RNA recombination frequency than other human CoVs. In addition, coronavirus RNA recombination primarily occurs at uridine (U)-enriched RNA sequences.

Vestibular Schwannoma Koos Grade II International Study of Active Surveillance Versus Stereotactic Radiosurgery: The VISAS-K2 Study.

Background And Objectives: This study assessed the efficacy and safety of stereotactic radiosurgery (SRS) in comparison with watchful waiting for managing Koos grade II vestibular schwannomas (VS).

Methods: A retrospective, multicentric analysis was conducted, focusing on patients with Koos grade II VS who either received SRS (SRS group) or were observed (observation group). To ensure comparability between groups, propensity score matching was used, including factors such as demographic characteristics, tumor dimensions, and hearing assessments.

Vestibular Schwannoma Koos Grade I International Study of Active Surveillance Versus Stereotactic Radiosurgery: The VISAS-K1 Study.

Background And Objective: This investigation evaluates the safety and efficacy of stereotactic radiosurgery (SRS) vs observation for Koos grade I vestibular schwannomas (VS).

Methods: In a multicenter study, we retrospectively analyzed data of patients with Koos grade I VS who underwent SRS (SRS group) or were observed (observation group). Propensity score matching was used to equilibrate demographics, tumor size, and audiometric data across groups.

Vestibular Schwannoma International Study of Active Surveillance Versus Stereotactic Radiosurgery: The VISAS Study.

Purpose: The present study assesses the safety and efficacy of stereotactic radiosurgery (SRS) versus observation for Koos grade 1 and 2 vestibular schwannoma (VS), benign tumors affecting hearing and neurological function.

Methods And Materials: This multicenter study analyzed data from Koos grade 1 and 2 VS patients managed with SRS (SRS group) or observation (observation group). Propensity score matching balanced patient demographics, tumor volume, and audiometry.

SARS-CoV-2 hijacks fragile X mental retardation proteins for efficient infection.

Viruses interact with numerous host factors to facilitate viral replication and to dampen antiviral defense mechanisms. We currently have a limited mechanistic understanding of how SARS-CoV-2 binds host factors and the functional role of these interactions. Here, we uncover a novel interaction between the viral NSP3 protein and the fragile X mental retardation proteins (FMRPs: FMR1 and FXR1-2).

SARS-CoV-2 Uses Nonstructural Protein 16 To Evade Restriction by IFIT1 and IFIT3.

Understanding the molecular basis of innate immune evasion by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important consideration for designing the next wave of therapeutics. Here, we investigate the role of the nonstructural protein 16 (NSP16) of SARS-CoV-2 in infection and pathogenesis. NSP16, a ribonucleoside 2'--methyltransferase (MTase), catalyzes the transfer of a methyl group to mRNA as part of the capping process.

SARS-CoV-2 Uses Nonstructural Protein 16 to Evade Restriction by IFIT1 and IFIT3.

Unlabelled: Understanding the molecular basis of innate immune evasion by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important consideration for designing the next wave of therapeutics. Here, we investigate the role of the nonstructural protein 16 (NSP16) of SARS-CoV-2 in infection and pathogenesis. NSP16, a ribonucleoside 2'- methyltransferase (MTase), catalyzes the transfer of a methyl group to mRNA as part of the capping process.

Vaccination Decreases the Infectious Viral Load of Delta Variant SARS-CoV-2 in Asymptomatic Patients.

The Delta variant of SARS-CoV-2 has caused many breakthrough infections in fully vaccinated individuals. While vaccine status did not generally impact the number of viral RNA genome copies in nasopharyngeal swabs of breakthrough patients, as measured by Ct values, it has been previously found to decrease the infectious viral load in symptomatic patients. We quantified the viral RNA, infectious virus, and anti-spike IgA in nasopharyngeal swabs collected from individuals asymptomatically infected with the Delta variant of SARS-CoV-2.

QTQTN motif upstream of the furin-cleavage site plays a key role in SARS-CoV-2 infection and pathogenesis.

The furin cleavage site (FCS), an unusual feature in the SARS-CoV-2 spike protein, has been spotlighted as a factor key to facilitating infection and pathogenesis by increasing spike processing. Similarly, the QTQTN motif directly upstream of the FCS is also an unusual feature for group 2B coronaviruses (CoVs). The QTQTN deletion has consistently been observed in in vitro cultured virus stocks and some clinical isolates.

Nucleocapsid mutations in SARS-CoV-2 augment replication and pathogenesis.

While SARS-CoV-2 continues to adapt for human infection and transmission, genetic variation outside of the spike gene remains largely unexplored. This study investigates a highly variable region at residues 203-205 in the SARS-CoV-2 nucleocapsid protein. Recreating a mutation found in the alpha and omicron variants in an early pandemic (WA-1) background, we find that the R203K+G204R mutation is sufficient to enhance replication, fitness, and pathogenesis of SARS-CoV-2.

Delta spike P681R mutation enhances SARS-CoV-2 fitness over Alpha variant.

We report that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta spike mutation P681R plays a key role in the Alpha-to-Delta variant replacement during the coronavirus disease 2019 (COVID-19) pandemic. Delta SARS-CoV-2 efficiently outcompetes the Alpha variant in human lung epithelial cells and primary human airway tissues. The Delta spike mutation P681R is located at a furin cleavage site that separates the spike 1 (S1) and S2 subunits.

A new tool to probe SARS-CoV-2 variants.

Virus-like particles offer a new way to investigate genetic variation in SARS-CoV-2.

Analytical characterization of the SARS-CoV-2 EURM-017 reference material.

Background: Current serological methods for SARS-CoV-2 lack adequate standardization to a universal standard reference material. Standardization will allow comparison of results across various lab-developed and commercial assays and publications. SARS-CoV-2 EURM-017 is human sera reference material containing antibodies directed against SARS-CoV-2 proteins, S1/S2 (full-length spike [S]), S1 receptor-binding domain (S1 RBD), S1, S2, and nucleocapsid (N) protein.

Mouse-adapted SARS-CoV-2 protects animals from lethal SARS-CoV challenge.

The emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has resulted in a pandemic causing significant damage to public health and the economy. Efforts to understand the mechanisms of Coronavirus Disease 2019 (COVID-19) have been hampered by the lack of robust mouse models. To overcome this barrier, we used a reverse genetic system to generate a mouse-adapted strain of SARS-CoV-2.

Nucleocapsid mutations in SARS-CoV-2 augment replication and pathogenesis.

Unlabelled: While SARS-CoV-2 continues to adapt for human infection and transmission, genetic variation outside of the spike gene remains largely unexplored. This study investigates a highly variable region at residues 203-205 in the SARS-CoV-2 nucleocapsid protein. Recreating a mutation found in the alpha and omicron variants in an early pandemic (WA-1) background, we find that the R203K+G204R mutation is sufficient to enhance replication, fitness, and pathogenesis of SARS-CoV-2.

Delta spike P681R mutation enhances SARS-CoV-2 fitness over Alpha variant.

SARS-CoV-2 Delta variant has rapidly replaced the Alpha variant around the world. The mechanism that drives this global replacement has not been defined. Here we report that Delta spike mutation P681R plays a key role in the Alpha-to-Delta variant replacement.