Preparation of polyethyleneimine-modified chitosan/Ce-UIO-66 composite hydrogel for the adsorption of methyl orange.

In this work, a polyethyleneimine-modified chitosan/Ce-UIO-66 composite hydrogel (PEI-CS/Ce-UIO-66) was prepared using the ex-situ blend method. The synthesized composite hydrogel was characterized by SEM, EDS, XRD, FTIR, BET, XPS, and TG techniques, while the zeta potential was recorded for sample analysis. The adsorbent performance was studied by conducting adsorption experiments using methyl orange (MO), which showed that PEI-CS/Ce-UIO-66 exhibited excellent MO adsorption properties (900.5 ± 19.09 mg/g). The adsorption kinetics of PEI-CS/Ce-UIO-66 could be explained by the pseudo-second-order kinetic model, and its isothermal adsorption followed the Langmuir model. Thermodynamics showed that the adsorption was spontaneous and exothermic at low temperatures. MO could interact with PEI-CS/Ce-UIO-66 via electrostatic interaction, π-π stacking, and hydrogen bonding. The results indicated that the PEI-CS/Ce-UIO-66 composite hydrogel could potentially be used for the adsorption of anionic dyes.

Pollen tube emergence is mediated by ovary-expressed ALCATRAZ in cucumber.

Pollen tube guidance within female tissues of flowering plants can be divided into preovular guidance, ovular guidance and a connecting stage called pollen tube emergence. As yet, no female factor has been identified to positively regulate this transition process. In this study, we show that an ovary-expressed bHLH transcription factor Cucumis sativus ALCATRAZ (CsALC) functions in pollen tube emergence in cucumber. CsALC knockout mutants showed diminished pollen tube emergence, extremely reduced entry into ovules, and a 95% reduction in female fertility. Further examination showed two rapid alkalinization factors CsRALF4 and CsRALF19 were less expressed in Csalc ovaries compared to WT. Besides the loss of male fertility derived from precocious pollen tube rupture as in Arabidopsis, Csralf4 Csralf19 double mutants exhibited a 60% decrease in female fertility due to reduced pollen tube distribution and decreased ovule targeting efficiency. In brief, CsALC regulates female fertility and promotes CsRALF4/19 expression in the ovary during pollen tube guidance in cucumber.

Steric effects of CN vacancies for boosting CO2 electroreduction to CO with ultrahigh selectivity.

In the electrochemical reduction of CO2 to CO, controlling the binding of the *COOH intermediate is key to adjusting the selectivity and catalytic activity of the CO product. Herein, we report that CN vacancies were used to control the binding of the *COOH intermediate on a Co PBA-VCN catalyst treated by H2 cold plasma bombardment to improve the CO2RR into CO. The CN vacancies can tune the local electronic structure and coordination environment of CoIII-CN-CoII (Co-PBA-VCN) with a high CO faradaic efficiency close to 100% with remarkable durability (>87 h), and a low onset overpotential of 0.17 V in CO2RR. The steric effects of the VCN can decrease the free energy barrier of the rate limiting step for the formation of *COOH which can further crack into *CO on the active site of the Co near the VCN. This work provides a new strategy to tune the binding of the *COOH intermediate on the catalyst surface by new vacancies of VCN to enhance the CO2RR into a single product.

Genotype distribution and evolutionary analysis of rotavirus associated with acute diarrhea outpatients in Hubei, China, 2013-2016.

Group A human rotaviruses (RVAs) annually cause the deaths of 215,000 infants and young children. To understand the epidemiological characteristics and genetic evolution of RVAs, we performed sentinel surveillance on RVA prevalence in a rotavirus-surveillance network in Hubei, China. From 2013 to 2016, a total of 2007 fecal samples from hospital outpatients with acute gastroenteritis were collected from four cities of Hubei Province. Of the 2007 samples, 153 (7.62%) were identified positive for RVA by real-time RT-PCR. RVA infection in Hubei mainly occurred in autumn and winter. The highest detection rate of RVA infection was in 1-2 years old of outpatients (16.97%). No significant difference of RVA positive rate was observed between females and males. We performed a phylogenetic analysis of the G/P genotypes based on the partial VP7/VP4 gene sequences of RVAs. G9P[8] was the most predominant strain in all four years but the prevalence of G2P[4] genotype increased rapidly since 2014. We reconstructed the evolutionary time scale of RVAs in Hubei, and found that the evolutionary rates of the G9, G2, P[8], and P[4] genotypes of RVA were 1.069 â€‹× â€‹10-3, 1.029 â€‹× â€‹10-3, 1.283 â€‹× â€‹10-3 and 1.172 â€‹× â€‹10-3 nucleotide substitutions/site/year, respectively. Importantly, using a molecular clock model, we showed that most G9, G2, P[8], and P[4] genotype strains dated from the recent ancestor in 2005, 2005, 1993, and 2013, respectively. The finding of the distribution of RVAs in infants and young children in Hubei Province will contribute to the understanding of the epidemiological characteristics and genetic evolution of RVAs in China.

Preparation and application of polyethyleneimine-modified corncob magnetic gel for removal of Pb(ii) and Cu(ii) ions from aqueous solution.

As a biomass resource, corncob is a kind of agricultural by-product with wide sources and low cost. Because its composition contains a large number of functional polymers such as cellulose, chitosan, and semi chitosan, corncob can be chemically modified to prepare a variety of adsorption materials. In this study, a magnetic gel material (PEI-CC@Fe3O4) consisting of corncob modified by glutaraldehyde-crosslinked polyethyleneimine (PEI) was successfully prepared and applied to the adsorption of heavy metal ions in aqueous solutions. The structure, thermal stability, and adsorption of heavy metal ions of the magnetic gel material (PEI-CC@Fe3O4) were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction phase analysis (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The results showed that PEI was crosslinked to the corncob through Aldol reaction and Schiff-base reaction. The heavy metal ion adsorption experiment showed that the PEI-CC@Fe3O4 had better adsorption toward divalent copper ions and divalent lead ions at 303 K, and the maximum adsorption capacities reached 459.4 mg g-1 and 290.8 mg g-1, respectively. Moreover, the study of isothermal adsorption and adsorption kinetics shows that the adsorption process is pseudo-second-order kinetics model adsorption, which belongs to Langmuir isothermal adsorption. Such excellent adsorption performance will contribute to the application of corncob biomass materials in industrial polluted wastewater.

As(III) Exposure Induces a Zinc Scarcity Response and Restricts Iron Uptake in High-Level Arsenic-Resistant Paenibacillus taichungensis Strain NC1.

The Gram-positive bacterium Paenibacillus taichungensis NC1 was isolated from the Zijin gold-copper mine and shown to display high resistance to arsenic (MICs of 10 mM for arsenite in minimal medium). Genome sequencing indicated the presence of a number of potential arsenic resistance determinants in NC1. Global transcriptomic analysis under arsenic stress showed that NC1 not only directly upregulated genes in an arsenic resistance operon but also responded to arsenic toxicity by increasing the expression of genes encoding antioxidant functions, such as cat, perR, and gpx. In addition, two highly expressed genes, marR and arsV, encoding a putative flavin-dependent monooxygenase and located adjacent to the ars resistance operon, were highly induced by As(III) exposure and conferred resistance to arsenic and antimony compounds. Interestingly, the zinc scarcity response was induced under exposure to high concentrations of arsenite, and genes responsible for iron uptake were downregulated, possibly to cope with oxidative stress associated with As toxicity. IMPORTANCE Microbes have the ability to adapt and respond to a variety of conditions. To better understand these processes, we isolated the arsenic-resistant Gram-positive bacterium Paenibacillus taichungensis NC1 from a gold-copper mine. The transcriptome responding to arsenite exposure showed induction of not only genes encoding arsenic resistance determinants but also genes involved in the zinc scarcity response. In addition, many genes encoding functions involved in iron uptake were downregulated. These results help to understand how bacteria integrate specific responses to arsenite exposure with broader physiological responses.

Formation of protonated water-hydrogen clusters in an ion trap mass spectrometer at room temperature.

Protonated water-hydrogen clusters [H+(H2O)n·m(H2)] present an interesting model for fundamental water research, but their formation and isolation presents considerable experimental challenges. Here, we report the detection of [H+(H2O)n·m(H2)] (2 ≤ n ≤ 3, m ≤ 2) clusters alongside protonated water clusters H+(H2O)n (2 ≤ n ≤ 3) in a linear ion trap mass spectrometer under two different experimental conditions: (1) when water vapor was ionized by +5.5 kV ambient corona discharge in front of the mass spectrometer inlet; (2) when isolated H+(H2O)n clusters were exposed to H2 gas inside the linear trap. Chemical assignment of [H+(H2O)n·m(H2)] clusters was confirmed using reference experiments with isotopically labeled water and deuterium. Also, the formation of H2 gas in the corona discharge area was indicated by a flame test. Overall, our findings clearly indicate that [H+(H2O)n·m(H2)] clusters can be produced at room temperature through the association of protonated water clusters H+(H2O)n with H2 gas, without any cooling necessary. A mechanism for the formation of the protonated water-hydrogen complexes was proposed. Our results also suggest that the association of water ions with H2 gas may play a notable role in corona discharge ionization processes, such as atmospheric pressure chemical ionization, and may be partially responsible for the stabilization of reactive radical species occasionally reported in corona discharge ionization experiments.

Acute pancreatitis, a rare complication of afferent loop obstruction: A case report.

Afferent loop (A-loop) obstruction presenting as acute pancreatitis is a rare clinical entity. We report a case of A-loop obstruction that occurred 15 years after Billroth II gastrectomy, leading to acute pancreatitis and accompanied by duodenal perforation and peritonitis. A 63-year-old man complaining of upper abdominal pain, distention, and nausea was referred to our hospital. The patient was previously treated with antibiotics and gastrointestinal decompression at the primary healthcare institute after being diagnosed with acute pancreatitis. However, the symptoms did not improve. Upon inter-hospital transportation, he experienced a period of relief from the pain but soon developed signs of diffuse peritonitis. Laboratory examination showed elevated serum amylase and lipase. A computed tomography scan revealed slight edema of the pancreas, a dilated and fluid-filled bowel loop across the mid-abdomen, and fluid accumulation in the abdominal cavity and pelvis. An emergency laparotomy was conducted, followed by symptomatic treatments. The patient had an uneventful recovery and was discharged in 4 weeks.

Drastic decline in sera neutralization against SARS-CoV-2 Omicron variant in Wuhan COVID-19 convalescents.

Global concern has been raised by the emergence and rapid transmission of the heavily mutated SARS-CoV-2 Omicron variant (B.1.1.529). So far, the infection features and immune escape ability of the Omicron variant have not been extensively studied. Here, we produced the Omicron pseudovirus and compared its entry, membrane fusion, and immune escape efficiency with the original strain and the dominating Delta variant. We found the Omicron variant showed slightly higher infectivity than the Delta variant and a similar ability to compete with the Delta variant in using Angiotensin-converting enzyme 2 (ACE2) in a BHK21-ACE2 cell line. However, the Omicron showed a significantly reduced fusogenicity than the original strain and the Delta variant in both BHK21-ACE2 and Vero-E6 cells. The neutralization assay testing the Wuhan convalescents' sera one-year post-infection showed a more dramatic reduction (10.15 fold) of neutralization against the Omicron variant than the Delta variant (1.79 fold) compared with the original strain with D614G. Notably, immune-boosting through three vaccine shots significantly improved the convalescents' immunity against the Omicron variants. Our results reveal a reduced fusogenicity and a striking immune escape ability of the Omicron variant, highlighting the importance of booster shots against the challenge of the SARS-CoV-2 antigenic drift.

Antibody neutralization to SARS-CoV-2 and variants after 1 year in Wuhan, China.

Most COVID-19 convalescents can build effective anti-SARS-CoV-2 humoral immunity, but it remains unclear how long it can maintain and how efficiently it can prevent the reinfection of the emerging SARS-CoV-2 variants. Here, we tested the sera from 248 COVID-19 convalescents around 1 year post-infection in Wuhan, the earliest known epicenter. SARS-CoV-2 immunoglobulin G (IgG) was well maintained in most patients and potently neutralizes the infection of the original strain and the B.1.1.7 variant. However, varying degrees of immune escape was observed on the other tested variants in a patient-specific manner, with individuals showing remarkably broad neutralization potency. The immune escape can be largely attributed to several critical spike mutations. These results suggest that SARS-CoV-2 can elicit long-lasting immunity but this is escaped by the emerging variants.

Co-selection of antibiotic resistance genes, and mobile genetic elements in the presence of heavy metals in poultry farm environments.

Environmental selection of antibiotic resistance genes (ARGs) is considered to be caused by antibiotic or metal residues, frequently used in livestock. In this study we examined three commercial poultry farms to correlate the co-occurrence patterns of antibiotic and metal residues to the presence of ARGs. We quantified 283 ARGs, 12 mobile genetic elements (MGEs), 49 targeted antibiotics, 7 heavy metals and sequenced 16S rRNA genes. The abundance and type of ARG were significantly enriched in manure while soil harbored the most diverse bacterial community. Procrustes analysis displayed significant correlations between ARGs/MGEs and the microbiome. Cadmium (Cd), arsenic (As), zinc (Zn), copper (Cu) and lead (Pb) were responsible for a majority of positive correlations to ARGs when compared to antibiotics. Integrons and transposons co-occurred with ARGs corresponding to 9 classes of antibiotics, especially Class1 integrase intI-1LC. Redundancy analysis (RDA) and Variance partitioning analysis (VPA) showed that antibiotics, metals, MGEs and bacteria explain solely 0.7%, 5.7%, 12.4%, and 21.9% of variances of ARGs in the microbial community, respectively. These results suggested that bacterial composition and horizontal gene transfer were the major factors shaping the composition of ARGs; Metals had a bigger effect on ARG profile than detected antibiotics in this study.

Angiotensin-Converting Enzyme Genotype-Specific Immune Response Contributes to the Susceptibility of COVID-19: A Nested Case-Control Study.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of coronavirus disease 2019 (COVID-19), which has resulted in a global pandemic. Methodology: We used a two-step polymerase chain reaction to detect the ACE genotype and ELISA kits to detect the cytokine factor. We also used proteomics to identify the immune pathway related to the ACE protein expression. Result: In this study, we found that the angiotensin-converting enzyme (ACE) deletion polymorphism was associated with the susceptibility to COVID-19 in a risk-dependent manner among the Chinese population. D/D genotype distributions were higher in the COVID-19 disease group than in the control group (D/D odds ratio is 3.87 for mild (p value < 0.0001), 2.59 for moderate (p value = 0.0002), and 4.05 for severe symptoms (p value < 0.0001), logic regression analysis. Moreover, genotype-specific cytokine storms and immune responses were found enriched in patients with the ACE deletion polymorphism, suggesting the contribution to the susceptibility to COVID-19. Finally, we identified the immune pathway such as the complement system related to the ACE protein expression of patients by lung and plasma proteomics. Conclusion: Our results demonstrated that it is very important to consider gene polymorphisms in the population to discover a host-based COVID-19 vaccine and drug design for preventive and precision medicine.

Efficient COI barcoding using high throughput single-end 400 bp sequencing.

BACKGROUND: Over the last decade, the rapid development of high-throughput sequencing platforms has accelerated species description and assisted morphological classification through DNA barcoding. However, the current high-throughput DNA barcoding methods cannot obtain full-length barcode sequences due to read length limitations (e.g. a maximum read length of 300 bp for the Illumina's MiSeq system), or are hindered by a relatively high cost or low sequencing output (e.g. a maximum number of eight million reads per cell for the PacBio's SEQUEL II system). RESULTS: Pooled cytochrome c oxidase subunit I (COI) barcodes from individual specimens were sequenced on the MGISEQ-2000 platform using the single-end 400 bp (SE400) module. We present a bioinformatic pipeline, HIFI-SE, that takes reads generated from the 5' and 3' ends of the COI barcode region and assembles them into full-length barcodes. HIFI-SE is written in Python and includes four function modules of filter, assign, assembly and taxonomy. We applied the HIFI-SE to a set of 845 samples (30 marine invertebrates, 815 insects) and delivered a total of 747 fully assembled COI barcodes as well as 70 Wolbachia and fungi symbionts. Compared to their corresponding Sanger sequences (72 sequences available), nearly all samples (71/72) were correctly and accurately assembled, including 46 samples that had a similarity score of 100% and 25 of ca. 99%. CONCLUSIONS: The HIFI-SE pipeline represents an efficient way to produce standard full-length barcodes, while the reasonable cost and high sensitivity of our method can contribute considerably more DNA barcodes under the same budget. Our method thereby advances DNA-based species identification from diverse ecosystems and increases the number of relevant applications.

Effect of fermentation and postcooking procedure on quality parameters and volatile compounds of beef jerky.

In this study, jerky samples were prepared from seasoned beef with and without the addition of starter culture. They were then dried or fried and analyzed to identify the quality parameters and volatile flavor compounds. Samples (starter and control) were divided into drying (inoculated-drying, I-D; noninoculated-drying, N-D) and frying (inoculated-frying, I-F; noninoculated-frying, N-F) groups. Water activity (a w), lightness (L*), and redness (a*) values were significantly affected (p < .001) by the postcooking procedures (drying or frying). Hardness, chewiness, and resilience were significantly lower in the dried groups than in the fried groups (p < .05). The formation of volatile compounds was affected by cooking treatment, with the highest levels observed in the I-F group. After frying, the most abundant flavor compounds in the I-D and N-D groups were terpenes and sulfur-containing compounds, followed by aromatic hydrocarbons, ketones, and alcohols. The most common compounds among all groups were acetoin, D-limonene, anethole, styrene, and tetramethylpyrazine. Overall, the jerky in the I-F group had the best color and tenderness scores among all groups.

Novel One-Step Single-Tube Nested Quantitative Real-Time PCR Assay for Highly Sensitive Detection of SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) has become a public health emergency. The reverse transcriptase real-time quantitative PCR (qRT-PCR) test is currently considered as the gold standard in the laboratory for the etiological detection of COVID-19. However, qRT-PCR results could be false-negative due to the inadequate sensitivity of qRT-PCR. In this study, we have developed and evaluated a novel one-step single-tube nested quantitative real-time PCR (OSN-qRT-PCR) assay for the highly sensitive detection of SARS-CoV-2 targeting the ORF1ab and N genes. The sensitivity of the OSN-qRT-PCR assay was 1 copy/reaction and 10-fold higher than that of the commercial qRT-PCR kit (10 copies/reaction). The clinical performance of the OSN-qRT-PCR assay was evaluated using 181 clinical samples. Among them, 14 qRT-PCR-negative samples (7 had no repetitive results and 7 had no cycle threshold (CT) values) were detected by OSN-qRT-PCR. Moreover, the 7 qRT-PCR-positives in the qRT-PCR gray zone (CT values of ORF1ab ranged from 37.48 to 39.07, and CT values of N ranged from 37.34 to 38.75) were out of the gray zone and thus were deemed to be positive by OSN-qRT-PCR, indicating that the positivity of these samples is confirmative. Compared to the qRT-PCR kit, the OSN-qRT-PCR assay revealed higher sensitivity and specificity, showing better suitability to clinical applications for the detection of SARS-CoV-2 in patients with low viral load.

Comparative Insights Into the Complete Genome Sequence of Highly Metal Resistant Cupriavidus metallidurans Strain BS1 Isolated From a Gold-Copper Mine.

The highly heavy metal resistant strain Cupriavidus metallidurans BS1 was isolated from the Zijin gold-copper mine in China. This was of particular interest since the extensively studied, closely related strain, C. metallidurans CH34 was shown to not be only highly heavy metal resistant but also able to reduce metal complexes and biomineralizing them into metallic nanoparticles including gold nanoparticles. After isolation, C. metallidurans BS1 was characterized and complete genome sequenced using PacBio and compared to CH34. Many heavy metal resistance determinants were identified and shown to have wide-ranging similarities to those of CH34. However, both BS1 and CH34 displayed extensive genome plasticity, probably responsible for significant differences between those strains. BS1 was shown to contain three prophages, not present in CH34, that appear intact and might be responsible for shifting major heavy metal resistance determinants from plasmid to chromid (CHR2) in C. metallidurans BS1. Surprisingly, the single plasmid - pBS1 (364.4 kbp) of BS1 contains only a single heavy metal resistance determinant, the czc determinant representing RND-type efflux system conferring resistance to cobalt, zinc and cadmium, shown here to be highly similar to that determinant located on pMOL30 in C. metallidurans CH34. However, in BS1 another homologous czc determinant was identified on the chromid, most similar to the czc determinant from pMOL30 in CH34. Other heavy metal resistance determinants such as cnr and chr determinants, located on megaplasmid pMOL28 in CH34, were shown to be adjacent to the czc determinant on chromid (CHR2) in BS1. Additionally, other heavy metal resistance determinants such as pbr, cop, sil, and ars were located on the chromid (CHR2) and not on pBS1 in BS1. A diverse range of genomic rearrangements occurred in this strain, isolated from a habitat of constant exposure to high concentrations of copper, gold and other heavy metals. In contrast, the megaplasmid in BS1 contains mostly genes encoding unknown functions, thus might be more of an evolutionary playground where useful genes could be acquired by horizontal gene transfer and possibly reshuffled to help C. metallidurans BS1 withstand the intense pressure of extreme concentrations of heavy metals in its environment.

Atraumatic splenic rupture was attributed to intra-cystic haemorrhage and hypersplenism in a patient with cirrhosis and portal hypertension: A case report.

Liver cirrhosis with splenomegaly and portal hypertension has been described in the medical literature as increasing the risk of splenic rupture. We report a case of atraumatic splenic rupture in a male with liver cirrhosis associated with splenomegaly, which was further complicated by hypersplenism and intra-cystic haemorrhage in the spleen. The 56-year-old man was hospitalized because of sudden onset of intermittent pain in the left quadrant abdomen with no history of trauma. Upon admission, the patient presented no fever, palpable abdominal tenderness, splenomegaly, and hypersplenism. Enhanced computed tomography revealed a splenic subcapsular haematoma connected to a cystic mass located at the splenic hilum and free fluid in the abdomen, which is indicative of splenic rupture. The patient underwent immediate laparotomy and splenectomy followed by proper management. Post-surgery diagnostic microscopy indicated liver steatosis, perivenular fibrosis, and regenerative nodules, which are suggestive of cirrhosis. The patient was discharged from the hospital with an uneventful recovery.

Preparation of the Coupling Co-Precipitation and Impregnation Catalyst Ag/Al2O3 with High Catalytic Performance in Selective Catalytic Reduction of NO with C3H6.

This brief paper reported an Ag/Al2O3 catalyst of high catalytic performance in C3H6-SCR (selective catalytic reduction with C3H6 as the reducer), and demonstrated a new strategy for the preparation of high active Ag/Al2O3 catalyst by the coupling co-precipitation and impregnation method. The results show that the coupling co-precipitation and impregnation catalyst was higher active than the usual impregnated catalyst in C3H6-SCR of NO with broad active temperature window (420-600 °C), and the highest conversions of NO achieved 91% over the coupling co-precipitation and impregnation catalyst at 500 °C. The porous structure parameter, crystal phase structure, surface acidity property and particle morphology of the Ag/Al2O3 catalyst were characterized by the Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectra and temperature programmed desorption of ammonia (NH3-TPD), respectively. Based on the characterization, it is found that the catalyst prepared by the coupling co-precipitation and impregnation method has smaller particles and better dispersion than the usual impregnated catalyst, and so the catalyst exhibited excellent catalytic activity. NH3-TPD results illustrate that the weak and medium-strong acid sites is conducive to the reactivity of catalyst.

A cross-reactive human monoclonal antibody targets the conserved H7 antigenic site A from fifth wave H7N9-infected humans.

Subtype H7 avian influenza viruses have been found to be associated with human infection and represent a risk for global public health. In 2013, the emergence of H7N9 virus in human beings and persistent human infection in China raised the most serious pandemic threat. Here we identified a human monoclonal antibody, P52E03, targeting the hemagglutinin (HA) of subtype H7 influenza viruses (H7 antigen), from a convalescent patient infected with H7N9 in 2017. P52E03 showed in vitro hemagglutination inhibiting (HI) and neutralizing activity against subtype H7 viruses belonging to both North American and Eurasian lineages. Moreover, it could prophylactically protect mice against weight loss and death caused by challenge with lethal H7N9 viruses in vivo and, therefore, is a candidate for development of antiviral agent against H7N9 infection. By generating escape mutant variants, we found that a single G151E substitution in the viral H7 antigenic site A could abort the neutralizing activity. Computational structural prediction of the P52E03/H7 complex revealed that residues including G151 in and around the conserved antigenic site A region are important for antigen recognition by the H7 cross-reactive antibody. Finally, we found that the P52E03 germline precursor (gHgL) antibody recognizes HA with measurable affinity, suggesting that its epitope is vulnerable to the human immune system and might elicit neutralizing antibodies (nAbs) in vivo after vaccination.