Insect Cell-Based Quadrivalent Seasonal Influenza Virus-like Particles Vaccine Elicits Potent Immune Responses in Mice.

Influenza viruses can cause highly infectious respiratory diseases, posing noteworthy epidemic and pandemic threats. Vaccination is the most cost-effective intervention to prevent influenza and its complications. However, reliance on embryonic chicken eggs for commercial influenza vaccine production presents potential risks, including reductions in efficacy due to HA gene mutations and supply delays due to scalability challenges. Thus, alternative platforms are needed urgently to replace egg-based methods and efficiently meet the increasing demand for vaccines. In this study, we employed a baculovirus expression vector system to engineer HA, NA, and M1 genes from seasonal influenza strains A/H1N1, A/H3N2, B/Yamagata, and B/Victoria, generating virus-like particle (VLP) vaccine antigens, H1N1-VLP, H3N2-VLP, Yamagata-VLP, and Victoria-VLP. We then assessed their functional and antigenic characteristics, including hemagglutination assay, protein composition, morphology, stability, and immunogenicity. We found that recombinant VLPs displayed functional activity, resembling influenza virions in morphology and size while maintaining structural integrity. Comparative immunogenicity assessments in mice showed that our quadrivalent VLPs were consistent in inducing hemagglutination inhibition and neutralizing antibody titers against homologous viruses compared to both commercial recombinant HA and egg-based vaccines (Vaxigrip). The findings highlight insect cell-based VLP vaccines as promising candidates for quadrivalent seasonal influenza vaccines. Further studies are worth conducting.

To develop a prognostic model for neoadjuvant immunochemotherapy efficacy in esophageal squamous cell carcinoma by analyzing the immune microenvironment.

Objective: The choice of neoadjuvant therapy for esophageal squamous cell carcinoma (ESCC) is controversial. This study aims to provide a basis for clinical treatment selection by establishing a predictive model for the efficacy of neoadjuvant immunochemotherapy (NICT). Methods: A retrospective analysis of 30 patients was conducted, divided into Response and Non-response groups based on whether they achieved major pathological remission (MPR). Differences in genes and immune microenvironment between the two groups were analyzed through next-generation sequencing (NGS) and multiplex immunofluorescence (mIF). Variables most closely related to therapeutic efficacy were selected through LASSO regression and ROC curves to establish a predictive model. An additional 48 patients were prospectively collected as a validation set to verify the model's effectiveness. Results: NGS suggested seven differential genes (ATM, ATR, BIVM-ERCC5, MAP3K1, PRG, RBM10, and TSHR) between the two groups (P < 0.05). mIF indicated significant differences in the quantity and location of CD3+, PD-L1+, CD3+PD-L1+, CD4+PD-1+, CD4+LAG-3+, CD8+LAG-3+, LAG-3+ between the two groups before treatment (P < 0.05). Dynamic mIF analysis also indicated that CD3+, CD8+, and CD20+ all increased after treatment in both groups, with a more significant increase in CD8+ and CD20+ in the Response group (P < 0.05), and a more significant decrease in PD-L1+ (P < 0.05). The three variables most closely related to therapeutic efficacy were selected through LASSO regression and ROC curves: Tumor area PD-L1+ (AUC= 0.881), CD3+PD-L1+ (AUC= 0.833), and CD3+ (AUC= 0.826), and a predictive model was established. The model showed high performance in both the training set (AUC= 0.938) and the validation set (AUC= 0.832). Compared to the traditional CPS scoring criteria, the model showed significant improvements in accuracy (83.3% vs 70.8%), sensitivity (0.625 vs 0.312), and specificity (0.937 vs 0.906). Conclusion: NICT treatment may exert anti-tumor effects by enriching immune cells and activating exhausted T cells. Tumor area CD3+, PD-L1+, and CD3+PD-L1+ are closely related to therapeutic efficacy. The model containing these three variables can accurately predict treatment outcomes, providing a reliable basis for the selection of neoadjuvant treatment plans.

MDCK-Adaptive Mutation of A169S Changes Glycosylation Pattern of Hemagglutinin and Enhances MDCK-Based H7N9 Vaccine Virus Production without Loss of Antigenicity and Immunogenicity.

The adaptation of egg-derived H7N9 candidate vaccine virus (CVV) in the mammalian cell line is an approach to developing a high-growth virus strain for the mass production of vaccine manufacturing. The adaptive mutations that occur in hemagglutinin (HA) are critical to the activity and potency of the vaccine virus. Previously, we identified a new mutation of A169S in the HA protein of an MDCK-adapted H7N9 vaccine virus (A/Anhui/2013, RG268); however, whether and how this mutation affects vaccine potency remain to be investigated. In this study, we serially passaged RG268 in MDCK cells and found that the HA titer and the TCID50 of the passaged virus RG268-M5 were 4-fold (HA units/50 µL) and 3.5-fold (log10 TCID50/mL) higher than those of the original CVV. By inspecting tandem MS spectra, we identified a new glycosylation site at N167 near the receptor binding site of the HA protein of RG268-M5. Flow cytometry results revealed that RG268-M5 could efficiently infect MDCK cells and initiate viral protein replication as well as that of RG268. Though the new glycosylation site is in the antigenic epitope of viral HA protein, the HI assay result indicated that the antigenicity of RG268-M5 was similar to RG268. Additionally, immunizing mice with RG268-M5 mixed aluminum hydroxide could induce potent antibody responses against the homologous and heterologous H7N9 viruses in vitro whereas the titers were comparable with those from the RG268 group. These results provide in-depth structural information regarding the effects of site-specific glycosylation on virus properties, which have implications for novel avian influenza vaccine development.

Functional analysis of Ornithine decarboxylase in manipulating the wing dimorphism in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae).

The brown planthopper (BPH, Nilaparvata lugens), a major insect pest of rice, can make a shift in wing dimorphism to adapt to complex external environments. Our previous study showed that NlODC (Ornithine decarboxylase in N. lugens) was involved in wing dimorphism of the brown planthopper. Here, further experiments were conducted to reveal possible molecular mechanism of NlODC in manipulating the wing dimorphism. We found that the long-winged rate (LWR) of BPH was significantly reduced after RNAi of NlODC or injection of DFMO (D, L-α-Difluoromethylornithine), and LWR of males and females significantly decreased by 21.7% and 34.6%, respectively. Meanwhile, we also examined the contents of three polyamines under DFMO treatment and found that the contents of putrescine and spermidine were significantly lower compared to the control. After 3rd instar nymphs were injected with putrescine and spermidine, LWR was increased significantly in both cases, and putrescine was a little bit more effective, with 5.6% increase in males and 11.4% in females. Three days after injection of dsNlODC, injection of putrescine and spermidine rescued LWR to the normal levels. In the regulation of wing differentiation in BPH, NlODC mutually antagonistic to NlAkt may act through other signaling pathways rather than the classical insulin signaling pathway. This study illuminated a physiological function of an ODC gene involved in wing differentiation in insects, which could be a potential target for pest control.

Cost-effective complete genome sequencing using the MinION platform for identification of recombinant enteroviruses.

IMPORTANCE: By employing a cost-effective approach for complete genome sequencing, the study has enabled the identification of novel enterovirus strains and shed light on the genetic exchange events during outbreaks. The success rate of genome sequencing and the scalability of the protocol demonstrate its practical utility for routine enterovirus surveillance. Moreover, the study's findings of recombinant strains of EVA71 and CVA2 contributing to epidemics in Malaysia and Taiwan emphasize the need for accurate detection and characterization of enteroviruses. The investigation of the whole genome and upstream ORF sequences has provided insights into the evolution and spread of enterovirus subgenogroups. These findings have important implications for the prevention, control, and surveillance of enteroviruses, ultimately contributing to the understanding and management of enterovirus-related illnesses.

How online food delivery platforms contributed to the resilience of the urban food system in China during the COVID-19 pandemic.

We use high-frequency data to quantify the nature and performance of online food delivery platforms during the COVID-19 pandemic in urban China, and to estimate the short- and long-term effects of lockdown and reopening measures. A staggered difference-in-differences (DID) estimation strategy and event study approach are used to identify the effects of lockdown and reopening measures on the performance of online food delivery platforms and restaurants. The results indicate that some restaurants continued to operate and offer online food delivery while lockdowns were in effect. Both the number of operating restaurants and their online food delivery services rebounded and experienced further growth after lockdowns were lifted. The adjustment path of the online food delivery business following the implementation of lockdowns differed from the adjustment path following the lifting of lockdowns. The lockdown and reopening measures did not affect all types of restaurant/cuisine equally. We also examine possible impact mechanisms of lockdown measures on online food delivery and restaurants, and conduct robustness checks to confirm the stability of the main findings. This study contributes to the existing literature by confirming the positive contribution of online food delivery to the resilience of urban food systems in response to unexpected external shocks. Our results have implications for the design of policies to guarantee food supply and help urban food systems adapt to unexpected shocks.

Characterization and Immunogenicity of Influenza H7N9 Vaccine Antigens Produced Using a Serum-Free Suspension MDCK Cell-Based Platform.

Human infections with avian-origin H7N9 influenza A viruses were first reported in China, and an approximately 38% human mortality rate was described across six waves from February 2013 to September 2018. Vaccination is one of the most cost-effective ways to reduce morbidity and mortality during influenza epidemics and pandemics. Egg-based platforms for the production of influenza vaccines are labor-intensive and unable to meet the surging demand during pandemics. Therefore, cell culture-based technology is becoming the alternative strategy for producing influenza vaccines. The current influenza H7N9 vaccine virus (NIBRG-268), a reassortant virus from A/Anhui/1/2013 (H7N9) and egg-adapted A/PR/8/34 (H1N1) viruses, could grow efficiently in embryonated eggs but not mammalian cells. Moreover, a freezing-dry formulation of influenza H7N9 vaccines with long-term stability will be desirable for pandemic preparedness, as the occurrence of influenza H7N9 pandemics is not predictable. In this study, we adapted a serum-free anchorage-independent suspension Madin-Darby Canine Kidney (MDCK) cell line for producing influenza H7N9 vaccines and compared the biochemical characteristics and immunogenicity of three influenza H7N9 vaccine antigens produced using the suspension MDCK cell-based platform without freeze-drying (S-WO-H7N9), the suspension MDCK cell-based platform with freeze-drying (S-W-H7N9) or the egg-based platform with freeze-drying (E-W-H7N9). We demonstrated these three vaccine antigens have comparable biochemical characteristics. In addition, these three vaccine antigens induced robust and comparable neutralizing antibody (NT; geometric mean between 1016 and 4064) and hemagglutinin-inhibition antibody (HI; geometric mean between 640 and 1613) titers in mice. In conclusion, the serum-free suspension MDCK cell-derived freeze-dried influenza H7N9 vaccine is highly immunogenic in mice, and clinical development is warranted.

Clinicopathological and prognostic significance of NM23 expression in patients with non-small cell lung cancer: A systematic review and meta-analysis.

BACKGROUND: There is a heated debate on the clinicopathological features and prognostic significance with non-metastasis 23 (NM23) expression in patients with non-small cell lung cancer (NSCLC). Thus, we conducted this meta-analysis to evaluate the clinicopathological features and prognostic significance of NM23 for NSCLC patients. METHODS: Pubmed, Embase, and Web of Science were exhaustively searched to identify relevant studies published prior to March, 2020. Odds radios (ORs) and hazard radios with 95% confidence intervals (CIs) were calculated to summarize the statistics of clinicopathological and prognostic assessments. Q-test and I2-statistic were utilized to assess heterogeneity across the included studies. We also performed subgroup analyses and meta-regression analyses to identify the source of heterogeneity. Publication bias was detected by Begg and Egger tests. Sensitivity analysis was used to value the stability of our results. All the data were analyzed using statistical packages implemented in R version 4.0.5. RESULTS: Data from a total of 3170 patients from 36 studies were extracted. The meta-analysis revealed that low expression of NM23 was correlated with higher risk of NSCLC (OR = 4.35; 95% CI: 2.76-6.85; P < .01), poorer tumor node metastasis (TNM) staging (OR = 1.39; 95% CI: 1.01-1.90; P = .04), poorer differentiation degree (OR = 1.37; 95% CI: 1.01-1.86; P = .04), positive lymph node metastasis (OR = 1.83; 95% CI: 1.22-2.74; P < .01), lung adenocarcinoma (OR = 1.45; 95% CI: 1.20-1.75; P < .01), and poorer 5-year overall survival (OS) rate (hazard radio = 2.33; 95%CI: 1.32-4.11; P < .01). The subgroup analyses and meta-regression analyses suggested that the "Publication year", "Country", "Sample size", and "Cutoff value" might be the source of heterogeneity in TNM staging, differentiation degree, and lymph node metastasis. Both Begg test and Egger test verified that there were publication bias in 5-year OS rate. Sensitivity analysis supported the credibility of the results. CONCLUSION: The reduced NM23 expression is strongly associated with higher risk of NSCLC, higher TNM staging, poorer differentiation degree, positive lymph node metastasis, lung adenocarcinoma, and poorer 5-year OS rate in NSCLC patients, which indicated that NM23 could serve as a biomarker predicating the clinicopathological and prognostic significance of NSCLC.

Multiple indicators of household dietary diversity in rural China: Effects of income and dietary knowledge.

OBJECTIVE: The aim of this study was to examine the association among family income, dietary knowledge, their interaction, and the multiple household dietary diversity indices (HDDIs), including dietary diversity score (DDS), entropy index (EI), Shannon equitability index (SEI), Herfindahl index (HI), and Simpson index (SI). METHODS: Based on 24-h dietary recall data collected from 1076 rural households in three provinces of Central China, we calculated HDDIs and compared them according to different levels of income and dietary knowledge. A set of multivariate linear regression were further established and estimated to examine the association among family income, dietary knowledge, and household dietary diversity. RESULTS: Although the calculation formulas are different, the distributions of the five diversity indices, namely, DDS, EI, SEI, HI, and SI are similar. Family income and dietary knowledge were significantly and positively correlated with various HDDIs (P < 0.01) in addition to HI. Specifically, with a 1-unit (10 000 yuan [US $1545]) income increase, the DDIs respectively changed by 1.70% (DDS), 1.23% (EI), 0.92% (SEI), -0.62% (HI, reverse), and 0.45% (SI). With a 1-point dietary knowledge score increase, the DDIs changed by 0.91% (DDS), 1.33% (EI), 1.29% (SEI), -1.19% (HI, reverse), and 0.81% (SI). The interaction effect of income and dietary knowledge on HDDIs were significantly and negatively correlated with various HDDIs (P < 0.05) in addition to HI. CONCLUSIONS: The present findings indicated that with an increase in income and dietary knowledge, rural residents in China would consume more diversified foods. There was a substitution effect of family income and dietary knowledge on HDDIs; that is, with an increase in family income, the effect of dietary knowledge on HDDIs would decrease. The findings of this study contributed to a better understanding of issues related to the dietary diversity of rural residents in China in the context of rising income and residents' increasing dietary knowledge.

The Impacts of Urbanization and Dietary Knowledge on Seaweed Consumption in China.

Edible seaweed, a nutrient-rich and sustainable food, has a long dietary history in China. To get a better understanding of the seaweed consumption of consumers in China, this study investigates the quantity and trend of seaweed consumption of Chinese residents and employs a Tobit model to examine the effects of urbanization and dietary knowledge on seaweed consumption among residents. The results show an increasing trend of household seaweed consumption in China, including both seaweeds consumed at home (SAH) and seaweeds consumed away from home (SAFH). Households in urban areas consumed more seaweeds on average than those in rural areas. Urbanization promotes total household seaweed consumption, including SAH and SAFH, whilst dietary knowledge has a significantly positive impact on total household seaweed consumption and SAH. The findings supplement empirical evidence on the seaweed consumption behavior of Chinese residents and have important policy implications for further promoting Chinese seaweeds consumption in the context of urbanization and increasing dietary knowledge.

2,3,5,4'-Tetrahydroxystilbene-2-O-ß-d-glucoside promotes the effects of dental pulp stem cells on rebuilding periodontal tissues in experimental periodontal defects.

BACKGROUND: This study aimed to investigate the regenerative effects of 2,3,5,4'-tetrahydroxystilbene-2-O-ß-d-glucoside (THSG)-treated human dental pulp stem cells (DPSC) on the healing of experimental periodontal defects in rats. METHODS: The maxillary first molars of 30 male Sprague-Dawley rats were extracted, and after healing, bilateral periodontal defects were surgically created mesially in second molars. The defects were treated with Matrigel (as control), DPSC, or DPSC + THSG. After 2 weeks, the healed defects were evaluated using microcomputed tomography and through histological and immunohistochemical analyses. RESULTS: In the microcomputed tomography analysis, more new bone formation in the DPSC and DPSC + THSG groups was observed compared with the control group. The periodontal bone supporting ratio in site with DPSC + THSG was significantly higher than that in DPSC. Histologically, an enhanced new bone formation and more significant periodontal attachment were observed in the DPSC + THSG group. The expression levels of proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), and osteopontin (OPN) in the DPSC + THSG group were significantly greater than those in other groups. CONCLUSIONS: THSG-revolutionized DPSCs significantly shortened the regenerative period of periodontal defects by enhancing the cell recruitment and possibly the angiogenesis in rat models, which illustrate the critical implications for a clinical application and provide a novel tactic for periodontitis treatment.

Development and Evaluation of Vero Cell-Derived Master Donor Viruses for Influenza Pandemic Preparedness.

The embryonated egg-based platform currently produces the majority of seasonal influenza vaccines by employing a well-developed master donor virus (MDV, A/PR/8/34 (PR8)) to generate high-growth reassortants (HGRs) for A/H1N1 and A/H3N2 subtypes. Although the egg-based platform can supply enough seasonal influenza vaccines, it cannot meet surging demands during influenza pandemics. Therefore, multi-purpose platforms are desirable for pandemic preparedness. The Vero cell-based production platform is widely used for human vaccines and could be a potential multi-purpose platform for pandemic influenza vaccines. However, many wild-type and egg-derived influenza viruses cannot grow efficiently in Vero cells. Therefore, it is critical to develop Vero cell-derived high-growth MDVs for pandemic preparedness. In this study, we evaluated two in-house MDVs (Vero-15 and VB5) and two external MDVs (PR8 and PR8-HY) to generate Vero cell-derived HGRs for five avian influenza viruses (AIVs) with pandemic potentials (H5N1 clade 2.3.4, H5N1 clade 2.3.2.1, American-lineage H5N2, H7N9 first wave and H7N9 fifth wave). Overall, no single MDV could generate HGRs for all five AIVs, but this goal could be achieved by employing two in-house MDVs (vB5 and Vero-15). In immunization studies, mice received two doses of Vero cell-derived inactivated H5N1 and H7N9 whole virus antigens adjuvanted with alum and developed robust antibody responses.

COVID-19 in the Greater Mekong Subregion: how resilient are rural households?

In this paper we submit some thoughts on the possible implications of the COVID-19 pandemic for rural people in the countries of the Greater Mekong Subregion (GMS). We base our observations and conclusions on our long-term research experience in the region. The paper focuses on the economics of rural households during this crisis period and its aftermath. We conclude that country differences clearly exist due to their different stages of development. However, while rural households belong to the Corona risk groups, they are also resilient to such a shock. We submit that Governments in the GMS should strengthen policies that conserve the safety-net function of rural villages.

Development of high-growth influenza H7N9 prepandemic candidate vaccine viruses in suspension MDCK cells.

BACKGROUND: Influenza vaccine manufacturers traditionally use egg-derived candidate vaccine viruses (CVVs) to produce high-yield influenza viruses for seasonal or pandemic vaccines; however, these egg-derived CVVs need an adaptation process for the virus to grow in mammalian cells. The low yields of cell-based manufacturing systems using egg-derived CVVs remain an unsolved issue. This study aimed to develop high-growth cell-derived CVVs for MDCK cell-based vaccine manufacturing platforms. METHODS: Four H7N9 CVVs were generated in characterized Vero and adherent MDCK (aMDCK) cells. Furthermore, reassortant viruses were amplified in adherent MDCK (aMDCK) cells with certification, and their growth characteristics were detected in aMDCK cells and new suspension MDCK (sMDCK) cells. Finally, the plaque-forming ability, biosafety, and immunogenicity of H7N9 reassortant viruses were evaluated. RESULTS: The HA titers of these CVVs produced in proprietary suspension MDCK (sMDCK) cells and chicken embryos were 2- to 8-fold higher than those in aMDCK cells. All H7N9 CVVs showed attenuated characteristics by trypsin-dependent plaque assay and chicken embryo lethality test. The alum-adjuvanted NHRI-RG5 (derived from the fifth wave H7N9 virus A/Guangdong/SP440/2017) vaccine had the highest immunogenicity and cross-reactivity among the four H7N9 CVVs. Finally, we found that AddaVax adjuvant improved the cross-reactivity of low pathogenic H7N9 virus against highly pathogenic H7N9 viruses. CONCLUSIONS: Our study indicates that cell-derived H7N9 CVVs possessed high growth rate in new sMDCK cells and low pathogenicity in chicken embryo, and that CVVs generated by this platform are also suitable for both cell- and egg-based prepandemic vaccine production.

Seroprevalence of EV-A71 neutralizing antibodies following the 2011 epidemic in HCMC, Vietnam.

Enterovirus-A71 (EV-A71) cyclically causes hand-foot-mouth disease (HFMD) epidemics in Asian children. An EV-A71 epidemic occurred in Southern Vietnam in 2011, but its scale is not clear. We collected residual sera from non-HFMD Vietnamese inpatients in 2012-2013 to determine seroprevalence of EV-A71 neutralizing antibodies, and measured cross-reactive neutralizing antibody titers against three EV-A71 genogroups. About 23.5% of 1-year-old children in Southern Vietnam has been infected by EV-A71, and the median age of infection was estimated to be 3 years. No significant antigenic variation could be detected among the three EV-A71 genogroups. The high seroprevalence of EV-A71 neutralizing antibody in children living in southern Vietnam indicates the necessity of introducing EV-A71 vaccines in southern Vietnam, particularly for children under 6 months of age. Moreover, it is critical to understand EV-A71 disease burden for formulating national vaccination policy.

Aspirin Versus Clopidogrel Monotherapy for the Secondary Prevention of Recurrent Cerebrovascular Attack Following Previous Ischemic Stroke in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis.

INTRODUCTION: Type 2 diabetes mellitus (T2DM) and stroke are two different diseases, but have many aspects in common. Aspirin is recommended as an initial treatment for the secondary prevention of recurrent ischemic stroke in patients with T2DM. However, clopidogrel is an oral antiplatelet drug that might be another choice in case of aspirin intolerance. In this analysis, we aimed to systematically compare aspirin versus clopidogrel monotherapy for the secondary prevention of recurrent cerebrovascular attack following previous ischemic stroke in patients with T2DM. METHODS: Online medical databases including Web of Science, MEDLINE, Cochrane central, EMBASE and http://www.ClinicalTrials.com were searched for published articles that satisfied the inclusion and exclusion criteria of this study. Recurrent stroke, fatal stroke, cerebral hemorrhage, myocardial infarction and mortality were considered the main end points in these patients with T2DM. RevMan 5.3 software was used to statistically analyze the data representing each subgroup. Risk ratios (RRs) with 95% confidence intervals (CIs) were used to represent the results following analysis. RESULTS: A total of 9218 participants with T2DM who were previously affected by ischemic stroke were included in this analysis, whereby 4917 were assigned to aspirin and 4301 to clopidogrel. This current analysis showed that there was no significant difference in recurrent stroke rate (RR: 0.79, 95% CI: 0.61-1.02; P = 0.07) observed with aspirin versus clopidogrel in these patients with T2DM. The risk of fatal stroke (RR: 0.88, 95% CI: 0.39-1.98; P = 0.76), cerebral hemorrhage (RR: 0.65, 95% CI: 0.38-1.11; P = 0.12), myocardial infarction (RR: 0.88, 95% CI: 0.43-1.79; P = 0.71) and mortality (RR: 1.07, 95% CI: 0.90-1.27; P = 0.44) were also similarly manifested. CONCLUSION: Clopidogrel monotherapy was neither inferior nor superior to aspirin monotherapy for the secondary prevention of recurrent cerebrovascular attack following previous ischemic stroke in patients with T2DM. Hence, clopidogrel or aspirin monotherapy is equally safe and effective in these patients with T2DM.

Development and characterization of standard reagents for cell-based prepandemic influenza vaccine products.

Outbreaks of infection by novel avian influenza virus strains in humans cause public health issues worldwide, and the development of vaccines against such novel strains is the most effective method for the prevention of these virus outbreaks. All types of vaccines must be tested for potency before use; thus, quantitative potency assays are needed for influenza vaccines. The single radial immunodiffusion (SRID) assay is considered the gold standard for quantification of influenza virus antigens, and the SRID reference reagents are essential for the determination of vaccine potency. However, it remains debatable whether reference reagents derived from egg-based vaccine platforms can be used to precisely quantify non-egg-derived vaccines; thus, influenza vaccine production using cell-based platforms has attracted increasing attention. To evaluate the utility of reference reagents derived from a cell-based influenza vaccine platform, we prepared cell-based reference reagents from MDCK cell-grown viruses and compared them with egg-derived reference reagents. A primary liquid standard (PLS) was purified from cell-derived candidate influenza vaccine viruses, and hemagglutinin (HA) antigen content was determined by a densitometric method. The produced PLS could be stored at 4°C for more than 10 months. We also established a simple HA protein purification method for goat antiserum preparation, and the performance of the resulting antiserum was compared to that of standard reagents obtained using different production platforms. The results of this study indicate that these reference reagents can be used for both cell-based and egg-based production platforms and that the differences between these two types of platforms are negligible.

Impacts of the COVID-19 pandemic on consumers' food safety knowledge and behavior in China.

This study assesses the impacts of the COVID-19 pandemic on Chinese residents' food safety knowledge and behavior, and explores the possible influence mechanism, namely, focus on media information. The study is based on internet survey data of 1 373 residents in China. A series of econometric models are developed to estimate food safety knowledge and behavior of residents. Both the descriptive and econometric results indicate that the existence of COVID-19 cases in a community has a significantly positive effect on residents' food safety knowledge and behavior. Residents focusing on food safety-related information tend to have higher food safety knowledge and practice food safety behavior. When controlling the variable focused on food safety-related information, the marginal effects of the existence of COVID-19 cases in a community on residents' food safety knowledge and behavior significantly decrease. However, the decrease in consumers' food safety knowledge is quite minor. Hence, the COVID-19 pandemic indeed improves Chinese residents' food safety knowledge and behavior, while focus on food safety-related information is an important mechanism for improving food safety behavior. Moreover, the estimation results of the simultaneous equations model reveal that consumers' food safety knowledge has a significant and positive effect on their food safety behavior. Heterogeneous impacts of the COVID-19 pandemic on residents' food safety knowledge and behavior among different regions and income groups are observed. The findings of this study provide evidence that public health events could enhance residents' safety awareness and behavior, while residents' focus on relevant information plays an important role in improving knowledge and impacting behavior.

Establishment of Asia-Pacific Network for Enterovirus Surveillance.

Enteroviruses (EV), the major pathogens of hand, foot, and mouth disease (HFMD) and herpangina, affect millions of children each year. Most human enteroviruses cause self-limited infections except polioviruses, enterovirus A71 (EV-A71), enterovirus D68 (EV-D68), and several echoviruses (Echo) and coxsackieviruses (CV). Especially, EV-A71 has repeatedly caused large-scale outbreaks in the Asia-Pacific region since 1997. Some Asian countries have experienced cyclical outbreaks of severe EV-A71 infections and initiated development of EV-A71 vaccines. Five EV-A71 vaccine candidates have been clinically evaluated and three of them were approved for marketing in China. However, none of the China-approved products seek marketing approval in other countries. This situation supports a role for collaboration among Asian countries to facilitate clinical trials and licensure of EV-A71 vaccines. Additionally, enterovirus D68 outbreaks have been reported in the US and Taiwan currently and caused severe complications and deaths. Hence, an Asia-Pacific Network for Enterovirus Surveillance (APNES) has been established to estimate disease burden, understand virus evolution, and facilitate vaccine development through harmonizing laboratory diagnosis and data collection. Founded in 2017, the APNES is comprised of internationally recognized experts in the field of enterovirus in Asian countries working to raise awareness of this potentially fatal and debilitating disease. This article demonstrated the summaries of the first expert meeting, 2017 International Workshop on Enterovirus Surveillance and Vaccine Development, held by APNES in Taipei, Taiwan, March 2017.

Process development for pandemic influenza VLP vaccine production using a baculovirus expression system.

BACKGROUND: Influenza viruses cause hundreds of thousands of respiratory diseases worldwide each year, and vaccination is considered the most effective approach for preventing influenza annual epidemics or pandemics. Since 1950, chicken embryonated eggs have been used as the main method for producing seasonal influenza vaccines. However, this platform has the main drawback of a lack of scale-up flexibility, and thus, egg-based vaccine manufacturers cannot supply sufficient doses within a short period for use for pandemic prevention. As a result, strategies for reducing the manufacturing time and increasing production capacity are urgently needed. Non-virion vaccine methods have been considered an alternative strategy against an influenza pandemic, and the purpose of maintaining an immunogenic capsule structure with infectious properties appears to be met by the virus-like particle (VLP) platform. RESULTS: An influenza H7N9-TW VLP production platform using insect cells, which included the expression of hemagglutinin (HA), NA, and M1 proteins, was established. To scale up H7N9-TW VLP production, several culture conditions were optimized to obtain a higher production yield. A high level of dissolved oxygen (DO) could be critical to H7N9-TW VLP production. If the DO was maintained at a high level, the HA titer obtained in the spinner flask system with ventilation was similar to that obtained in a shake flask. In this study, the HA titer in a 5-L bioreactor with a well-controlled DO level was substantially improved by 128-fold (from 4 HA units (HAU)/50 µL to 512 HAU/50 µL). CONCLUSIONS: In this study, a multigene expression platform and an effective upstream process were developed. Notably, a high H7N9-TW VLP yield was achieved using a two-step production strategy while a high DO level was maintained. The upstream process, which resulted in high VLP titers, could be further used for large-scale influenza VLP vaccine production.