Molecular determinants of enterovirus 71 viral entry: cleft around GLN-172 on VP1 protein interacts with variable region on scavenge receptor B 2.

Enterovirus 71 (EV71) is one of the major pathogens that cause hand, foot, and mouth disease outbreaks in young children in the Asia-Pacific region in recent years. Human scavenger receptor class B 2 (SCARB2) is the main cellular receptor for EV71 on target cells. The requirements of the EV71-SCARB2 interaction have not been fully characterized, and it has not been determined whether SCARB2 serves as an uncoating receptor for EV71. Here we compared the efficiency of the receptor from different species including human, horseshoe bat, mouse, and hamster and demonstrated that the residues between 144 and 151 are critical for SCARB2 binding to viral capsid protein VP1 of EV71 and seven residues from the human receptor could convert murine SCARB2, an otherwise inefficient receptor, to an efficient receptor for EV71 viral infection. We also identified that EV71 binds to SCARB2 via a canyon of VP1 around residue Gln-172. Soluble SCARB2 could convert the EV71 virions from 160 S to 135 S particles, indicating that SCARB2 is an uncoating receptor of the virus. The uncoating efficiency of SCARB2 significantly increased in an acidic environment (pH 5.6). These studies elucidated the viral capsid and receptor determinants of enterovirus 71 infection and revealed a possible target for antiviral interventions.

Mutations in HA and PA affect the transmissibility of H7N9 avian influenza virus in chickens.

Low pathogenic (LP) H7N9 avian influenza virus (AIV) emerged in 2013 and had spread widely over several months in China, experienced a noteworthy reduction in isolation rate in poultry and human since 2017. Here, we examined the transmission of H7N9 viruses to better understand viral spread and dissemination mechanisms. Three out of four viruses (2013-2016) could transmit in chickens through direct contact, and airborne transmission was confirmed in the JT157 (2016) virus. However, we did not detect the transmission of the two 2017 viruses, WF69 and AH395, through either direct or airborne exposure. Molecular analysis of genome sequence of two viruses identified eleven mutations located in viral proteins (except for matrix protein), such as PA (K362R and S364N) and HA (D167N, H7 numbering), etc. We explored the genetic determinants that contributed to the difference in transmissibility of the viruses in chickens by generating a series of reassortants in the JT157 background. We found that the replacement of HA gene in JT157 by that of WF69 abrogated the airborne transmission in recipient chickens, whereas the combination of HA and PA replacement led to the loss of airborne and direct contact transmission. Failure with contact transmission of the viruses has been associated with the emergence of the mutations D167N in HA and K362R and S364N in PA. Furthermore, the HA D167N mutation significantly reduced viral attachment to chicken lung and trachea tissues, while mutations K362R and S364N in PA reduced the nuclear transport efficiency and the PA protein expression levels in both cytoplasm and nucleus of CEF cells. The D167N substitution in HA reduced the H7N9 viral acid stability and avian-like receptor binding, while enhanced human-like receptor binding. Further analysis revealed these mutants grew poorly in vitro and in vivo. To conclude, H7N9 AIVs that contain mutations in the HA and PA protein reduced the viral transmissibility in chicken, and may pose a reduced threat for poultry but remain a heightened public health risk.

Genetic and antigenic diversity of H7N9 highly pathogenic avian influenza virus in China.

Avian influenza virus (AIV) H7N9 that emerged in 2013 in eastern China is a novel zoonotic agent mainly circulating in poultry without clinical signs but causing severe disease with high fatality in humans in more than 5 waves. Since the emergence of highly pathogenic (HP) H7N9 variants in 2016, it has induced heavy losses in the poultry industry leading to the implementation of an intensive nationwide vaccination program at the end of wave 5 (September 2017). To characterize the ongoing evolution of H7N9 AIV, we conducted analyses of H7N9 glycoprotein genes obtained from 2013 to 2019. Bayesian analyses revealed a decreasing population size of HP H7N9 variants post wave 5. Phylogenetic topologies revealed that two novel small subclades were formed and carried several fixed amino acid mutations that were along HA and NA phylogenetic trees since wave 5. Some of the mutations were located at antigenic sites or receptor binding sites. The antigenic analysis may reveal a significant antigenic drift evaluated by hemagglutinin inhibition (HI) assay and the antigenicity of H7N9 AIV might evolute in large leaps in wave 7. Molecular simulations found that the mutations (V135T, S145P, and L226Q) around the HA receptor pocket increased the affinity to α2,3-linked sialic acid (SIA) while decreased to α2,6-linked SIA. Altered affinity may suggest that HP H7N9 variations aggravate the pathogenicity to poultry but lessen the threat to public health. Selection analyses showed that the HP H7N9 AIV experienced an increasing selection pressure since wave 5, and the national implementation of vaccination might intensify the role of natural selection during the evolution waves 6 and 7. In summary, our data provide important insights about the genetic and antigenic diversity of circulating HP H7N9 viruses from 2017 to 2019. Enhanced surveillance is urgently warranted to understand the current situation of HP H7N9 AIV.

Induction of cross-group broadly reactive antibody response by natural H7N9 avian influenza virus infection and immunization with inactivated H7N9 vaccine in chickens.

Pre-existing immunity against the conserved haemagglutinin (HA) stalk underlies the elicitation of cross-group antibody induced by natural H7N9 virus infection and immunization in humans. However, whether broadly reactive antibodies can be induced by H7N9 infection and immunization in the absence of pre-existing stalk-specific immunity is unclear. In this study, antibody response induced by H7N9 virus infection and immunization with inactivated and viral-vectored H7N9 vaccines in naïve chickens was analysed. The results showed that H7N9 infection and immunization with inactivated vaccine resulted in potent induction of haemagglutination-inhibition (HI), virus neutralization (VN) and HA-binding antibodies, whereas Newcastle disease virus (NDV)-vectored H7N9 vaccine induced marginal HI and VN titres but high levels of HA-binding antibody. In addition, H7N9 infection and immunization induced stalk-specific antibodies in naïve chickens and these antibodies recognized different epitopes in the stalk. Virus infection and immunization with inactivated vaccine elicited antibodies cross-reactive with both group 1 and group 2 HAs, while antibodies induced by NDV-H7N9 vaccination showed a narrower cross-reactivity within group 2. Moreover, only homologous neutralizing activity of the sera against H7N9 virus was observed, and cross-binding antibodies did not show heterosubtypic neutralizing activity. Our results indicated that cross-group binding but non-neutralizing antibodies primarily targeting the stalk can be induced by natural H7N9 infection and immunization with inactivated vaccine in naïve chickens. This suggests that at least in a naïve chicken model, pre-existing stalk-specific immunity is not required for induction of broadly reactive antibodies. Additionally, H7N9-based immunogens may be explored as vaccine candidates or as a prime component to induce broadly protective influenza immunity.

Correction: Overexpression of wildtype EGFR is tumorigenic and denotes a therapeutic target in non-small cell lung cancer.

[This corrects the article DOI: 10.18632/oncotarget.6461.].

Overexpression of wildtype EGFR is tumorigenic and denotes a therapeutic target in non-small cell lung cancer.

Current guidelines for lung cancer treatment with EGFR tyrosine kinase inhibitors (TKI) include only patients with mutated EGFR, although some patients with wildtype EGFR (wt-EGFR) have exhibited positive responses to this therapy as well. Biomarkers predicting the benefit from EGFR-TKIs treatment remain to be determined for patients with wild-type EGFR.Here, we report that wt-EGFR overexpression transformed cells in vitro and induced tumorigenesis in vivo in transgenic mouse models. Wt-EGFR driven lung cancer was hypersensitive to TKI treatment in mouse model. Lung cancer patients with high-expression of wt-EGFR showed longer Overall Survival in comparison to low-expression patients after TKI treatment. Our data therefore suggest that treatment with EGFR inhibitors should be extended to include not only patients with mutated EGFR but also a subset of patients with overexpression of wt-EGFR.

Transcriptomic characterization of hepatocellular carcinoma with CTNNB1 mutation.

PURPOSE: Hepatocellular carcinoma (HCC) is the sixth most common solid tumor worldwide and the third leading cause of cancer-related death. HCC is a particularly serious threat to the Chinese population. Although many molecular alterations are known to be involved in the tumorigenesis of hepatocytes, no systemic survey has examined the somatic mutations in HCC samples from Chinese patients. Our goal was to elucidate somatic mutations in Chinese HCC patients and investigate the possible molecular mechanisms involved in tumorigenesis. EXPERIMENTAL DESIGN: A total of 110 hepatitis B virus (HBV)-positive HCC samples and 46 HBV-negative HCC samples were genotyped for hot-spot mutations in the CSF1R, CTNNB1, KRAS, BRAF, NRAS, ERBB2, MET, PIK3CA, JAK1, and SMO genes. The transcriptomes of the CTNNB1 mutation-positive HCC samples from the HBV-positive patients (CB+ HCC) were compared to adjacent non-cancerous livers, and significantly altered genes were functionally validated in vitro. RESULTS: CTNNB1 mutations accounted for the majority of the mutations detected in our study. A slightly higher mutation rate was found in the HBV-positive patients than in their negative counterparts. A distinct pattern of CTNNB1 mutation was detected in these two populations, and drastic changes at the transcriptomic level were detected in the CB+ tumors compared to adjacent non-cancerous livers. Potential tumor suppressors (FoxA3 and Onecut1) and oncogenes (MAFG and SSX1) were functionally validated. CONCLUSIONS: Our work is the first systemic characterization of oncogenic mutations in HCC samples from Chinese patients. Targeting the Wnt-ß-catenin pathway may represent a valid treatment option for Chinese HCC patients. Our work also suggests that targeting ONECUT1, FOXA3, SSX1, and MAFG may be a valid treatment option for CTNNB1 mutation positive HCC patients.