Early Introduction and Community Transmission of SARS-CoV-2 Omicron Variant, New York, New York, USA.

The Omicron variant of SARS-CoV-2 has become dominant in most countries and has raised significant global health concerns. As a global commerce center, New York, New York, USA, constantly faces the risk for multiple variant introductions of SARS-CoV-2. To elucidate the introduction and transmission of the Omicron variant in the city of New York, we created a comprehensive genomic and epidemiologic analysis of 392 Omicron virus specimens collected during November 25-December 11, 2021. We found evidence of 4 independent introductions of Omicron subclades, including the Omicron subclade BA.1.1 with defining substitution of R346K in the spike protein. The continuous genetic divergence within each Omicron subclade revealed their local community transmission and co-circulation in New York, including both household and workplace transmissions supported by epidemiologic evidence. Our study highlights the urgent need for enhanced genomic surveillance and effective response planning for better prevention and management of emerging SARS-CoV-2 variants.

Genomic annotation and molecular evolution of monkeypox virus outbreak in 2022.

Monkeypox virus (MPXV) has generally circulated in West and Central Africa since its emergence. Recently, sporadic MPXV infections in several nonendemic countries have attracted widespread attention. Here, we conducted a systematic analysis of the recent outbreak of MPXV-2022, including its genomic annotation and molecular evolution. The phylogenetic analysis indicated that the MPXV-2022 strains belong to the same lineage of the MPXV strain isolated in 2018. However, compared with the MPXV strain in 2018, in total 46 new consensus mutations were observed in the MPXV-2022 strains, including 24 nonsynonymous mutations. By assigning mutations to 187 proteins encoded by the MPXV genome, we found that 10 proteins in the MPXV are more prone to mutation, including D2L-like, OPG023, OPG047, OPG071, OPG105, OPG109, A27L-like, OPG153, OPG188, and OPG210 proteins. In the MPXV-2022 strains, four and three nucleotide substitutions are observed in OPG105 and OPG210, respectively. Overall, our studies illustrated the genome evolution of the ongoing MPXV outbreak and pointed out novel mutations as a reference for further studies.

The battle between host and SARS-CoV-2: Innate immunity and viral evasion strategies.

The SARS-CoV-2 virus, the pathogen causing COVID-19, has caused more than 200 million confirmed cases, resulting in more than 4.5 million deaths worldwide by the end of August, 2021. Upon detection of SARS-CoV-2 infection by pattern recognition receptors (PRRs), multiple signaling cascades are activated, which ultimately leads to innate immune response such as induction of type I and III interferons, as well as other antiviral genes that together restrict viral spread by suppressing different steps of the viral life cycle. Our understanding of the contribution of the innate immune system in recognizing and subsequently initiating a host response to an invasion of SARS-CoV-2 has been rapidly expanding from 2020. Simultaneously, SARS-CoV-2 has evolved multiple immune evasion strategies to escape from host immune surveillance for successful replication. In this review, we will address the current knowledge of innate immunity in the context of SARS-CoV-2 infection and highlight recent advances in the understanding of the mechanisms by which SARS-CoV-2 evades a host's innate defense system.

Cryo-EM structure of influenza virus RNA polymerase complex at 4.3 Å resolution.

Replication and transcription of influenza virus genome mainly depend on its RNA-dependent RNA polymerase (RdRP), composed of the PA, PB1, and PB2 subunits. Although extensively studied, the underlying mechanism of the RdRP complex is still unclear. Here we report the biochemical characterization of influenza RdRP subcomplex comprising PA, PB1, and N terminus of PB2, which exist as dimer in solution and can assemble into a tetramer state, regulated by vRNA promoter. Using single-particle cryo-electron microscopy, we have reconstructed the RdRP tetramer complex at 4.3 Å, highlighting the assembly and interfaces between monomers within the tetrameric structure. The individual RdRP subcomplex contains all the characterized motifs and appears as a cage-like structure. High-throughput mutagenesis profiling revealed that residues involved in the oligomer state formation are critical for viral life cycle. Our results lay a solid base for understanding the mechanism of replication of influenza and other negative-stranded RNA viruses.

Sequence analysis of the emerging SARS-CoV-2 variant Omicron in South Africa.

Despite the worldwide vaccination, the COVID-19 pandemic continues as SARS-CoV-2 evolves into numerous variants. Since the first identification of the novel SARS-CoV-2 variant of concern (VOC) Omicron on November 24th, 2021, from an immunocompromised patient in South Africa, the variant has overtaken Delta as the predominant lineage in South Africa and has quickly spread to over 40 countries. Here, we provide an initial molecular characterization of the Omicron variant through analyzing a large number of mutations, especially in the spike protein receptor-binding domain with their potential effects on viral infectivity and host immunity. Our analysis indicates that the Omicron variant has two subclades and may evolve from clade 20B instead of the currently dominant Delta variant. In addition, we have also identified mutations that may affect the ACE2 receptor and/or antibody bindings. Our study has raised additional questions on the evolution, transmission, virulence, and immune escape properties of this new Omicron variant.

Potential intervariant and intravariant recombination of Delta and Omicron variants.

Among numerous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concerns, Omicron is more infectious and immune-escaping, while Delta is more pathogenic. Here, we provide evidence for both intervariant and intravariant recombination of the rapidly evolving new SARS-CoV-2 genomes, including XD/XE/XF and BA.3, raising concerns of potential more infectious, immune-escaping, and disease-causing Omicron and Delta-Omicron variants.

Co-Infection with 4 Species of Mycobacteria Identified by Using Next-Generation Sequencing.

We identified co-infection with 4 species of mycobacteria in a woman in New York, New York, USA, by using next-generation sequencing. This procedure is useful for identifying co-infections with multiple mycobacteria, tracing the geographic origin of strains, investigating transmission dynamics in susceptible populations, and gaining insight into prevention and control.

Screening for Novel Small-Molecule Inhibitors Targeting the Assembly of Influenza Virus Polymerase Complex by a Bimolecular Luminescence Complementation-Based Reporter System.

Influenza virus RNA-dependent RNA polymerase consists of three viral protein subunits: PA, PB1, and PB2. Protein-protein interactions (PPIs) of these subunits play pivotal roles in assembling the functional polymerase complex, which is essential for the replication and transcription of influenza virus RNA. Here we developed a highly specific and robust bimolecular luminescence complementation (BiLC) reporter system to facilitate the investigation of influenza virus polymerase complex formation. Furthermore, by combining computational modeling and the BiLC reporter assay, we identified several novel small-molecule compounds that selectively inhibited PB1-PB2 interaction. Function of one such lead compound was confirmed by its activity in suppressing influenza virus replication. In addition, our studies also revealed that PA plays a critical role in enhancing interactions between PB1 and PB2, which could be important in targeting sites for anti-influenza intervention. Collectively, these findings not only aid the development of novel inhibitors targeting the formation of influenza virus polymerase complex but also present a new tool to investigate the exquisite mechanism of PPIs. IMPORTANCE Formation of the functional influenza virus polymerase involves complex protein-protein interactions (PPIs) of PA, PB1, and PB2 subunits. In this work, we developed a novel BiLC assay system which is sensitive and specific to quantify both strong and weak PPIs between influenza virus polymerase subunits. More importantly, by combining in silico modeling and our BiLC assay, we identified a small molecule that can suppress influenza virus replication by disrupting the polymerase assembly. Thus, we developed an innovative method to investigate PPIs of multisubunit complexes effectively and to identify new molecules inhibiting influenza virus polymerase assembly.

Potential for treatment and a Zika virus vaccine.

PURPOSE OF REVIEW: Zika virus (ZIKV) has only recently been exposed as a significant public health threat, and much of our limited knowledge of its pathogenesis and triggered immune responses were discovered in only the last few years. There are currently no ZIKV-specific therapeutics or vaccines available. This review seeks to bring the reader up-to-date with the latest developments in finding a way to combat this emerging infectious disease. RECENT FINDINGS: Current strategies used for developing ZIKV vaccines or treatments follow proven methods used against other flaviviruses. Unfortunately, ZIKV carries many unique challenges, such as the need to target drugs and vaccines towards immunocompromised populations (pregnant mothers and fetuses), the risk of stimulating harmful immune responses (either autoimmune or antibody-dependent enhancement of infection in those with previous flavivirus exposure), frequently silent infection that may delay treatment and increase risk of transmission to others, and multiple routes of transmission (arthropod vector, sexual, bloodborne, and potentially other body fluids). SUMMARY: Current medical recommendations are directed towards resolving symptoms and not the actual infection; however, ZIKV treatments and vaccines are in development. Vector control and travel restrictions to endemic areas may remain our only available interventions for some time.

Functional Genomics Reveals Linkers Critical for Influenza Virus Polymerase.

UNLABELLED: Influenza virus mRNA synthesis by the RNA-dependent RNA polymerase involves binding and cleavage of capped cellular mRNA by the PB2 and PA subunits, respectively, and extension of viral mRNA by PB1. However, the mechanism for such a dynamic process is unclear. Using high-throughput mutagenesis and sequencing analysis, we have not only generated a comprehensive functional map for the microdomains of individual subunits but also have revealed the PA linker to be critical for polymerase activity. This PA linker binds to PB1 and also forms ionic interactions with the PA C-terminal channel. Nearly all mutants with five-amino-acid insertions in the linker were nonviable. Our model further suggests that the PA linker plays an important role in the conformational changes that occur between stages that favor capped mRNA binding and cleavage and those associated with viral mRNA synthesis. IMPORTANCE: The RNA-dependent RNA polymerase of influenza virus consists of the PB1, PB2, and PA subunits. By combining genome-wide mutagenesis analysis with the recently discovered crystal structure of the influenza polymerase heterotrimer, we generated a comprehensive functional map of the entire influenza polymerase complex. We identified the microdomains of individual subunits, including the catalytic domains, the interaction interfaces between subunits, and nine linkers interconnecting different domains. Interestingly, we found that mutants with five-amino-acid insertions in individual linkers were nonviable, suggesting the critical roles these linkers play in coordinating spatial relationships between the subunits. We further identified an extended PA linker that binds to PB1 and also forms ionic interactions with the PA C-terminal channel.

A human antibody recognizing a conserved epitope of H5 hemagglutinin broadly neutralizes highly pathogenic avian influenza H5N1 viruses.

Influenza A virus infection is a persistent threat to public health worldwide due to its ability to evade immune surveillance through rapid genetic drift and shift. Current vaccines against influenza A virus provide immunity to viral isolates that are similar to vaccine strains. High-affinity neutralizing antibodies against conserved epitopes could provide immunity to diverse influenza virus strains and protection against future pandemic viruses. In this study, by using a highly sensitive H5N1 pseudotype-based neutralization assay to screen human monoclonal antibodies produced by memory B cells from an H5N1-infected individual and molecular cloning techniques, we developed three fully human monoclonal antibodies. Among them, antibody 65C6 exhibited potent neutralization activity against all H5 clades and subclades except for subclade 7.2 and prophylactic and therapeutic efficacy against highly pathogenic avian influenza H5N1 viruses in mice. Studies on hemagglutinin (HA)-antibody complexes by electron microscopy and epitope mapping indicate that antibody 65C6 binds to a conformational epitope comprising amino acid residues at positions 118, 121, 161, 164, and 167 (according to mature H5 numbering) on the tip of the membrane-distal globular domain of HA. Thus, we conclude that antibody 65C6 recognizes a neutralization epitope in the globular head of HA that is conserved among almost all divergent H5N1 influenza stains.

Constructing interface engineering and tailoring a nanoflower-like FeP/CoP heterostructure for enhanced oxygen evolution reaction.

The inexpensive and highly efficient electrocatalysts toward oxygen evolution reaction (OER) in water splitting electrolysis have displayed promising practical applications to relieve energy crisis. Herein, we prepared a high-yield and structurally regulated bimetallic cobalt-iron phosphide electrocatalyst by a facile one-pot hydrothermal reaction and subsequent low-temperature phosphating treatment. The tailoring of nanoscale morphology was achieved by varying the input ratio and phosphating temperature. Thus, an optimized FeP/CoP-1-350 sample with the ultra-thin nanosheets assembled into a nanoflower-like structure was obtained. FeP/CoP-1-350 heterostructure displayed remarkable activity toward the OER with a low overpotential of 276 mV at a current density of 10 mA cm-2, and a low Tafel slope of only 37.71 mV dec-1. Long-lasting durability and stability were maintained with the current with almost no obvious fluctuation. The enhanced OER activity was attributed to the presence of copious active sites from the ultra-thin nanosheets, the interface between CoP and FeP components, and the synergistic effect of Fe-Co elements in the FeP/CoP heterostructure. This study provides a feasible strategy to fabricate highly efficient and cost-effective bimetallic phosphide electrocatalysts.

SARS-CoV-2 virus NSP14 Impairs NRF2/HMOX1 activation by targeting Sirtuin 1.

Most deaths from the COVID-19 pandemic are due to acute respiratory distress syndrome (ARDS)-related respiratory failure. Cytokine storms and oxidative stress are the major players in ARDS development during respiratory virus infections. However, it is still unknown how oxidative stress is regulated by viral and host factors in response to SARS-CoV-2 infection. Here, we found that activation of NRF2/HMOX1 significantly suppressed SARS-CoV-2 replication in multiple cell types by producing the metabolite biliverdin, whereas SARS-CoV-2 impaired the NRF2/HMOX1 axis through the action of the nonstructural viral protein NSP14. Mechanistically, NSP14 interacts with the catalytic domain of the NAD-dependent deacetylase Sirtuin 1 (SIRT1) and inhibits its ability to activate the NRF2/HMOX1 pathway. Furthermore, both genetic and pharmaceutical evidence corroborated the novel antiviral activity of SIRT1 against SARS-CoV-2. Therefore, our findings reveal a novel mechanism by which SARS-CoV-2 dysregulates the host antioxidant defense system and emphasize the vital role played by the SIRT1/NRF2 axis in host defense against SARS-CoV-2.

The Evolutionary Dance between Innate Host Antiviral Pathways and SARS-CoV-2.

Compared to what we knew at the start of the SARS-CoV-2 global pandemic, our understanding of the interplay between the interferon signaling pathway and SARS-CoV-2 infection has dramatically increased. Innate antiviral strategies range from the direct inhibition of viral components to reprograming the host's own metabolic pathways to block viral infection. SARS-CoV-2 has also evolved to exploit diverse tactics to overcome immune barriers and successfully infect host cells. Herein, we review the current knowledge of the innate immune signaling pathways triggered by SARS-CoV-2 with a focus on the type I interferon response, as well as the mechanisms by which SARS-CoV-2 impairs those defenses.

One year of SARS-CoV-2 evolution.

Since the outbreak of SARS-CoV-2, the etiologic agent of the COVID-19 pandemic, the viral genome has acquired numerous mutations with the potential to increase transmission. One year after its emergence, we now further analyze emergent SARS-CoV-2 genome sequences in an effort to understand the evolution of this virus.

Mutations, Recombination and Insertion in the Evolution of 2019-nCoV.

Background: The 2019 novel coronavirus (2019-nCoV or SARS-CoV-2) has spread more rapidly than any other betacoronavirus including SARS-CoV and MERS-CoV. However, the mechanisms responsible for infection and molecular evolution of this virus remained unclear. Methods: We collected and analyzed 120 genomic sequences of 2019-nCoV including 11 novel genomes from patients in China. Through comprehensive analysis of the available genome sequences of 2019-nCoV strains, we have tracked multiple inheritable SNPs and determined the evolution of 2019-nCoV relative to other coronaviruses. Results: Systematic analysis of 120 genomic sequences of 2019-nCoV revealed co-circulation of two genetic subgroups with distinct SNPs markers, which can be used to trace the 2019-nCoV spreading pathways to different regions and countries. Although 2019-nCoV, human and bat SARS-CoV share high homologous in overall genome structures, they evolved into two distinct groups with different receptor entry specificities through potential recombination in the receptor binding regions. In addition, 2019-nCoV has a unique four amino acid insertion between S1 and S2 domains of the spike protein, which created a potential furin or TMPRSS2 cleavage site. Conclusions: Our studies provided comprehensive insights into the evolution and spread of the 2019-nCoV. Our results provided evidence suggesting that 2019-nCoV may increase its infectivity through the receptor binding domain recombination and a cleavage site insertion. One Sentence Summary: Novel 2019-nCoV sequences revealed the evolution and specificity of betacoronavirus with possible mechanisms of enhanced infectivity.

Zika virus vertical transmission in children with confirmed antenatal exposure.

We report Zika virus (ZIKV) vertical transmission in 130 infants born to PCR+ mothers at the time of the Rio de Janeiro epidemic of 2015-2016. Serum and urine collected from birth through the first year of life were tested by quantitative reverse transcriptase polymerase chain reaction (PCR) and/or IgM Zika MAC-ELISA. Four hundred and seven specimens are evaluated; 161 sera tested by PCR and IgM assays, 85 urines by PCR. Sixty-five percent of children (N = 84) are positive in at least one assay. Of 94 children tested within 3 months of age, 70% are positive. Positivity declines to 33% after 3 months. Five children are PCR+ beyond 200 days of life. Concordance between IgM and PCR results is 52%, sensitivity 65%, specificity 40% (positive PCR results as gold standard). IgM and serum PCR are 61% concordant; serum and urine PCR 55%. Most children (65%) are clinically normal. Equal numbers of children with abnormal findings (29 of 45, 64%) and normal findings (55 of 85, 65%) have positive results, p = 0.98. Earlier maternal trimester of infection is associated with positive results (p = 0.04) but not clinical disease (p = 0.98). ZIKV vertical transmission is frequent but laboratory confirmed infection is not necessarily associated with infant abnormalities.

Generation of a Live Attenuated Influenza Vaccine that Elicits Broad Protection in Mice and Ferrets.

New influenza vaccines that provide effective and broad protection are desperately needed. Live attenuated viruses are attractive vaccine candidates because they can elicit both humoral and cellular immune responses. However, recent formulations of live attenuated influenza vaccines (LAIVs) have not been protective. We combined high-coverage transposon mutagenesis of influenza virus with a rapid high-throughput screening for attenuation to generate W7-791, a live attenuated mutant virus strain. W7-791 produced only a transient asymptomatic infection in adult and neonatal mice even at doses 100-fold higher than the LD50 of the parent strain. A single administration of W7-791 conferred full protection to mice against lethal challenge with H1N1, H3N2, and H5N1 strains, and improved viral clearance in ferrets. Adoptive transfer of T cells from W7-791-immunized mice conferred heterologous protection, indicating a role for T cell-mediated immunity. These studies present an LAIV development strategy to rapidly generate and screen entire libraries of viral clones.

From Mosquitos to Humans: Genetic Evolution of Zika Virus.

Initially isolated in 1947, Zika virus (ZIKV) has recently emerged as a significant public health concern. Sequence analysis of all 41 known ZIKV RNA open reading frames to date indicates that ZIKV has undergone significant changes in both protein and nucleotide sequences during the past half century.