Publisher Correction: Sudden emergence of human infections with H7N9 avian influenza A virus in Hubei province, central China.

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Bat-Origin Coronaviruses Expand Their Host Range to Pigs.

Infections with bat-origin coronaviruses have caused severe illness in humans by 'host jump'. Recently, novel bat-origin coronaviruses were found in pigs. The large number of mutations on the receptor-binding domain allowed the viruses to infect the new host, posing a potential threat to both agriculture and public health.

Two genetically diverse H7N7 avian influenza viruses isolated from migratory birds in central China.

After the emergence of H7N9 avian influenza viruses (AIV) in early 2013 in China, active surveillance of AIVs in migratory birds was undertaken, and two H7N7 strains were subsequently recovered from the fresh droppings of migratory birds; the strains were from different hosts and sampling sites. Phylogenetic and sequence similarity network analyses indicated that several genes of the two H7N7 viruses were closely related to those in AIVs circulating in domestic poultry, although different gene segments were implicated in the two isolates. This strongly suggested that genes from viruses infecting migratory birds have been introduced into poultry-infecting strains.

New Threats from H7N9 Influenza Virus: Spread and Evolution of High- and Low-Pathogenicity Variants with High Genomic Diversity in Wave Five.

H7N9 virus has caused five infection waves since it emerged in 2013. The highest number of human cases was seen in wave 5; however, the underlying reasons have not been thoroughly elucidated. In this study, the geographical distribution, phylogeny, and genetic evolution of 240 H7N9 viruses in wave 5, including 35 new isolates from patients and poultry in nine provinces, were comprehensively analyzed together with strains from first four waves.

Crystal Structure of the Capsid Protein from Zika Virus.

Recently, Zika virus (ZIKV) emerged as a global public health concern and is distinct from other flaviviruses in many aspects, for example, causing transplacental infection, fetal abnormalities and vector-independent transmission through body fluids in humans. The capsid (C) protein is a multifunctional protein, since it binds to viral RNA in the process of nucleocapsid assembly and plays important roles in virus infection processes by interacting with cellular proteins, modulating cellular metabolism, apoptosis and immune response. Here we solved the crystal structure of ZIKV C protein at a resolution of 1.

Sudden emergence of human infections with H7N9 avian influenza A virus in Hubei province, central China.

There have been five waves of H7N9 avian influenza virus (AIV) infection in humans since its initial emergence in China in 2013, posing a significant threat to public health. Hubei province was free local transmission during the first four waves of H7N9 AIV. However, multiple cases of human H7N9 infection were reported in Hubei during January 2017.

Two reassortant types of highly pathogenic H5N8 avian influenza virus from wild birds in Central China in 2016.

Since 2016, the highly pathogenic avian influenza H5N8 virus has emerged in the Central Asian flyway and Europe, causing massive deaths in poultry and wild birds. In this study, we isolated and identified three H5N8 viruses from swan goose and black swans in Hubei province during the 2016/2017 winter season. Whole-genome sequencing and phylogenetic analysis revealed that the three viruses clustered into a group of H5N8 viruses from Qinghai Lake and Europe.

Characterization of avian influenza H9N2 viruses isolated from ostriches (Struthio camelus).

H9N2 subtype avian influenza viruses (AIVs) have been isolated from various species of wild birds and domestic poultry in the world, and occasionally transmitted to humans. Although H9N2 AIVs are seldom isolated from ostriches, seven such strains were isolated from sick ostriches in China between 2013 and 2014. Sequence analysis showed several amino acid changes relating to viral adaptation in mammals were identified.

Hemagglutinin-specific CD4 T-cell responses following 2009-pH1N1 inactivated split-vaccine inoculation in humans.

Influenza A virus remains a major threat to public health, and the inactivated split-virus vaccine is the most prevalent vaccine used worldwide. However, our knowledge about cellular immune responses to the inactivated influenza virus vaccine and its correlation with humoral responses are yet limited, which has restricted our understanding of the vaccine's protective mechanisms. Herein, in two clinical trials, T-cell responses specific for both previously identified human leucocyte antigen (HLA)-I-restricted epitopes from influenza virus and hemagglutinin (HA) protein were longitudinally investigated before, during, and after a two-dose vaccination with the inactivated 2009 pandemic H1N1 (2009-pH1N1) vaccine.

Synthesis of Sialic Acids, Their Derivatives, and Analogs by Using a Whole-Cell Catalyst.

Sialic acids (Sias) are important constituents of cell surface glycans. Ready access to Sias in large quantities would facilitate the development of carbohydrate-based vaccines and small-molecule drugs. We now present a facile method for synthesizing various natural forms and non-natural derivatives or analogs of Sias by using a whole-cell catalyst, which is constructed by adding a plasmid containing necessary enzyme genes into a metabolically engineered strain of Escherichia coli.

Monoclonal Antibodies against Zika Virus: Therapeutics and Their Implications for Vaccine Design.

Zika virus (ZIKV) has caused global concern due to its association with neurological complications in newborns and adults. Although no vaccines or antivirals against ZIKV infection have been approved to date, hundreds of monoclonal antibodies (MAbs) have been developed in a short period. Here, we first present a complete picture of the ZIKV MAbs and then focus on the neutralizing mechanisms and immune hot spots uncovered through structural studies, which provide insight for therapeutics and vaccine design.

Avian-to-Human Receptor-Binding Adaptation by Influenza A Virus Hemagglutinin H4.

Low-pathogenicity avian influenza viruses (LPAIVs) have caused a global concern to public health since the first novel LPAIV H7N9 outbreak occurred. The receptor-binding properties of the viral hemagglutinin are one key factor for efficient transmission and infection in humans. Recent evidence shows that H4 subtype viruses have been widely circulating in domestic poultry and human asymptomatic infections might have occurred.

Crystal Structure of the Marburg Virus Nucleoprotein Core Domain Chaperoned by a VP35 Peptide Reveals a Conserved Drug Target for Filovirus.

Filovirus nucleoprotein (NP), viral protein 35 (VP35), and polymerase L are essential for viral replication and nucleocapsid formation. Here, we identify a 28-residue peptide (NP binding peptide [NPBP]) from Marburg virus (MARV) VP35 through sequence alignment with previously identified Ebola virus (EBOV) NPBP, which bound to the core region (residues 18 to 344) of the N-terminal portion of MARV NP with high affinity. The crystal structure of the MARV NP core/NPBP complex at a resolution of 2.

Conserved Vδ1 Binding Geometry in a Setting of Locus-Disparate pHLA Recognition by δ/αβ T Cell Receptors (TCRs): Insight into Recognition of HIV Peptides by TCRs.

Given the limited set of T cell receptor (TCR) V genes that are used to create TCRs that are reactive to different ligands, such as major histocompatibility complex (MHC) class I, MHC class II, and MHC-like proteins (for example, MIC molecules and CD1 molecules), the Vδ1 segment can be rearranged with Dδ-Jδ-Cδ or Jα-Cα segments to form classical γδTCRs or uncommon αβTCRs using a Vδ1 segment (δ/αβTCR). Here we have determined two complex structures of the δ/αβTCRs (S19-2 and TU55) bound to different locus-disparate MHC class I molecules with HIV peptides (HLA-A*2402-Nef138-10 and HLA-B*3501-Pol448-9). The overall binding modes resemble those of classical αβTCRs but display a strong tilt binding geometry of the Vδ1 domain toward the HLA α1 helix, due to a conserved extensive interaction between the CDR1δ loop and the N-terminal region of the α1 helix (mainly in position 62).

Alternate binding modes of anti-CRISPR viral suppressors AcrF1/2 to Csy surveillance complex revealed by cryo-EM structures.

Bacteriophages encode anti-CRISPR suppressors to counteract the CRISPR/Cas immunity of their bacterial hosts, thus facilitating their survival and replication. Previous studies have shown that two phage-encoded anti-CRISPR proteins, AcrF1 and AcrF2, suppress the type I-F CRISPR/Cas system of Pseudomonas aeruginosa by preventing target DNA recognition by the Csy surveillance complex, but the precise underlying mechanism was unknown. Here we present the structure of AcrF1/2 bound to the Csy complex determined by cryo-EM single-particle reconstruction.

Development of a reverse transcription quantitative polymerase chain reaction-based assay for broad coverage detection of African and Asian Zika virus lineages.

The Zika virus (ZIKV) is an arbovirus that has spread rapidly worldwide within recent times. There is accumulating evidence that associates ZIKV infections with Guillain-Barré Syndrome (GBS) and microcephaly in humans. The ZIKV is genetically diverse and can be separated into Asian and African lineages.

Structure of the S1 subunit C-terminal domain from bat-derived coronavirus HKU5 spike protein.

Accumulating evidence indicates that MERS-CoV originated from bat coronaviruses (BatCoVs). Previously, we demonstrated that both MERS-CoV and BatCoV HKU4 use CD26 as a receptor, but how the BatCoVs evolved to bind CD26 is an intriguing question. Here, we solved the crystal structure of the S1 subunit C-terminal domain of HKU5 (HKU5-CTD), another BatCoV that is phylogenetically related to MERS-CoV but cannot bind to CD26.

Structural Biology of the Zika Virus.

Zika virus (ZIKV), a Flaviviridae family member transmitted to humans by mosquitoes, has emerged as a major health concern. ZIKV infections can cause serious neurological complications in adults, and infection in pregnant women can cause congenital malformations, including fetal and newborn microcephaly. In response to this emerging concern, the structural virology field was quick to explore the features of ZIKV.

The crystal structure of Zika virus NS5 reveals conserved drug targets.

Zika virus (ZIKV) has emerged as major health concern, as ZIKV infection has been shown to be associated with microcephaly, severe neurological disease and possibly male sterility. As the largest protein component within the ZIKV replication complex, NS5 plays key roles in the life cycle and survival of the virus through its N-terminal methyltransferase (MTase) and C-terminal RNA-dependent RNA polymerase (RdRp) domains. Here, we present the crystal structures of ZIKV NS5 MTase in complex with an RNA cap analogue (GpppA) and the free NS5 RdRp.

Ultrasensitive Ebola Virus Detection Based on Electroluminescent Nanospheres and Immunomagnetic Separation.

The 2014-16 Ebola virus (EBOV) outbreak in West Africa has attracted widespread concern. Rapid and sensitive detection methods are urgently needed for diagnosis and treatment of the disease. Here, we propose a novel method for EBOV detection based on efficient amplification of electroluminescent nanospheres (ENs) coupled with immunomagnetic separation.