Objective To prepare high-purity novel H7N9 avian influenza virus matrix protein 1 (M1) and high-affinity polyclonal antibodies against it.Methods Using the pGEX-6p-1 vector, a chimeric M1 (cM1) sequence was designed by fusing glutathione S-transferase (GST) and histidine (His) tags to the N- and C-termini of M1, respectively. Bioinformatics analysis of cM1 was performed. The verified recombinant expression vector pGEX-6p-1-cM1 was transformed into E. coli BL21(DE3) competent cells for isopropylthio-β-D-galactoside-induced expression. After scaling up the culture under optimal expression conditions, the induced products were purified separately by His-tag and GST-tag affinity chromatography. The purified target protein was analyzed via SDS-PAGE and used to immunize New Zealand white rabbit for polyclonal antibody production. The specificity and titer of antibodies were evaluated by Western blotting, indirect immunofluorescence assay (IFA), and indirect ELISA.Results High-purity cM1 was successfully prepared using a prokaryotic expression system, with apparent relative molecular weight of approximately 55 000. Polyclonal antibodies against cM1 were generated in a New Zealand white rabbit. IFA and Western blotting demonstrated that the polyclonal antibodies specifically recognized novel H7N9 avian influenza virus. Indirect ELISA results indicated an antibody titer of 1∶10 240.Conclusions Soluble expression and purification of high-purity cM1 are achieved using a prokaryotic expression system. The prepared polyclonal antibodies exhibit strong immunoreactivity and high titer, providing foundation for further exploration of M1 structure and function, as well as establishing rapid detection methods for H7N9 avian influenza virus.
Objective To compare 3 adjuvant diluents prepared in different proportions in order to screen long-acting adjuvant diluents of live classical swine fever (CSF) vaccine suitable for pig farms.Methods Six groups of diluents were prepared with 3 kinds of adjuvants AD05, aluminum hydroxide gel and IMS1313 at 5% and 10% volume fractions， respectively, and physiological saline was used as control. The appearance, pH, sterility, safety, titer and antibody tests were carried out. Based on various indicators, the best adjuvant diluent was screened for clinical trials with healthy piglets. Results All groups of adjuvant diluents dissolved CSF vaccine quickly, pH values were 6.8-7.2, and sterility and mycoplasma tests were all qualified. Anorexia and listlessness occurred in 1 piglet in 10% AD05 group, while no obvious symptoms occurred in other groups. The titer of 5% aluminum hydroxide gel group was 103.5 50% fluorescent antibody infectious dose（FAID50）, that of 10% aluminum hydroxide gel group was 102.4 FAID50, and those of other groups were all > 104.0 FAID50. At 90 d after immunization, only 5% and 10% AD05 groups obtained antibody positive rates > 95%. Based on various indicators and costs, 5% AD05 was selected as the adjuvant diluent of live CSF vaccine. In clinical trials, the positive rate of antibody against CSF reached 97% on the 30th day after immunization, and remained at 90% on the 130th day (175 days old), the blocking rate was 74.07%, with coefficient of variation at 0.19.Conclusion 5% AD05 adjuvant can be used as a long-acting adjuvant diluent of live CSF vaccine, which provides a new idea for large-scale pig farms to simplify the immunization program, reduce the stress of pigs and prevent CSF effectively.
Objective To investigate the feasibility of using polyvinylidene fluoride (PVDF) membrane sterilizing filtration during the production of the final bulk of Influenza Vaccine (Split Virion), Inactivated (Flu Vac).Methods PVDF sterilizing-grade filters were used to perform sterilizing filtration on the final bulk of Flu Vac. Filter compatibility, adsorption of vaccine components, bacterial retention, and product quality parameters of the Flu Vac final bulk after sterilizing filtration were measured.Results Under the established process conditions, the bubble point, flow time, weight, and appearance of the filtered samples all met the acceptance criteria, indicating good compatibility between the filter and samples. After sterilizing filtration, both hemagglutinin and protein contents of samples remained within 96%-104% of those in unfiltered samples, indicating minimal adsorption. The 0.22 μm PVDF sterilizing filter completely retained Brevundimonas diminuta in the final bulk of Flu Vac. There were no statistically significant differences between the hemagglutinin content of any influenza strain or the protein content before and after filtration (t=0.04-1.81, all P>0.05), whereas residual polysorbate 80 decreased after filtration (t=6.93, P<0.05). No adverse effects on the major quality attributes of the final bulk were observed. In addition, the homogeneity and shelf-life of the final bulk after sterilizing filtration met the established quality requirements.Conclusion PVDF sterilizing filtration is suitable for Flu Vac production, providing key data for the addition of sterilizing filtration step in the formulation of Flu Vac final bulk.
Objective To investigate the dialysis effect on Sabin strain inactivated poliovirus vaccine (sIPV) inactivation liquid by analyzing changes in sample components before and after dialysis.Methods Three batches each of types Ⅰ, Ⅱ, and Ⅲ sIPV inactivation liquids were dialyzed. The volume, D-antigen content, pH value, formaldehyde content and osmolality of samples before and after dialysis were determined.Results The volume differences of inactivation liquids before and after dialysis were ≤1 mL. The D-antigen recoveries of types Ⅰ, Ⅱ, and Ⅲ after dialysis were (95.08±3.71) %, (90.17±2.12) % and (98.96±1.24) %, respectively, all > 90%. The pH values of types Ⅰ and Ⅱ after dialysis both increased to 7.37±0.06, from 7.00±0.00 and 6.90±0.00, respectively, while pH increase in type Ⅲ（from 6.97±0.06 to 7.27±0.15） was not as significant. The pH values of all 3 types converged to the range of 7.30-7.40 after dialysis. The formaldehyde concentrations of types Ⅰ, Ⅱ, and Ⅲ before dialysis were 96-97, 94-96 and 94-98 μg/mL, respectively, and all decreased to below 1 μg/mL after dialysis with formaldehyde clearance rates all above 99%. After dialysis, the osmolalities of types Ⅰ, Ⅱ, Ⅲ decreased from (302±12), (391±5), (359±2) mOsm/kg to (282±2), (282±3), (282±3) mOsm/kg, respectively, and all stabilized at approximately 282 mOsm/kg.Conclusion Dialysis treatment of sIPV inactivation liquid can remove impurities while retain key target antigen activity, which meets the requirements for subsequent study.
Objective To evaluate the protective effects of 4 brands of serum-free cell cryopreservation media for the long-term cryopreservation of low-density serum-free suspension Madin Darby canine kidney（MDCK） cells, and to compare the impact of different cryopreservation conditions on post-thaw cell viability, proliferation capacity, and viral production performance.Methods Serum-free suspension MDCK-SFSU cells were aliquoted at 2×10⁶ cells per vial density and cryopreserved using 4 serum-free cryopreservation media（A、B、C、D）, with 10% dimethyl sulfoxide cryopreservation solution serving as the control. Cells were stored under ﹣80 ℃ or in liquid nitrogen for 0, 3, and 6 months. After thawing, cell viability was measured, growth curves and viability curves were drawn, and the ability to produce virus following influenza virus inoculation was assessed to comprehensively evaluate the cryopreservation efficacy.Results Media A, B, and C effectively cryopreserved low-density MDCK-SFSU cells at ﹣80 ℃ for 6 months. After thawing, cell viabilities of groups A, B, and C were statistically significantly higher than control group (F=247.00，P＜0.001), and were all >88%. Hemagglutination titers of virus producted by groups B and C were >9 log2 hemagglutination unit /50 μL. However, this protective effect did not occur in liquid nitrogen storage environment. Cryopreservation medium D and control groups showed inadequate protective effects under both low-temperature conditions.Conclusion Low-density, serum-free suspension MDCK cells can be successfully stored long-term at ﹣80 ℃ using cryopreservation medium B or C.
Objective To prepare antiserum against mumps virus genotype A strain S79 for the immunogenicity evaluation of traditional mumps vaccines and serological identification of genotype A strains, and to prepare antiserum against mumps virus F genotype strain QBB targeting epidemic variant strains, so as to monitor antigenic drift and evaluate the cross-neutralization ability of traditional mumps vaccines against epidemic wild strains.Method Mumps virus genotype A strain S79 and genotype F strain QBB were inoculated into Vero cells, harvested and purified by ultracentrifugation to prepare two immunogens， respectively.Two kinds of mumps virus antisera were prepared by mixing the two immunogens separately with Freund’s adjuvant at a volume ratio 1∶1， and immunizing Japanese white rabbits through multi-point subcutaneous injection on the back. PBS was used as control.The neutralization titer of serum antibodies was detected by neutralization test, the concentration of IgG antibody was detected by indirect ELISA, and the antigen-specific binding capacity of serum antibody was detected by Western blot.Results Two kinds of mumps virus antisera were prepared. The results of neutralization test showed that the 4th S79 virus immune serum completely neutralized 1 000 CCID50/mL S79 virus and QBB virus at 1∶1 024 and 1∶256 dilutions, respectively, while the 4th QBB virus immune serum completely neutralized 1 000 CCID50/mL S79 virus and QBB virus at 1∶2 048 and 1∶32 768 dilutions, respectively. Indirect ELISA showed that the IgG antibody titers of both S79 and QBB immune sera reached 1∶107 after the 4th immunization. The protein binding bands of QBB strain, S79 strain and truncated glycoprotein of mumps virus hemagglutinin-neuraminidase were detected by Western blot using both kinds of antisera.Conclusion The antisera of genotype A and F mumps virus are successfully prepared, which provide critical data support for immune effect evaluation of mumps vaccines, serological typing of strains and cross-genotype cross-protection research of vaccines.
Objective To establish and validate a specific activity detection method for the major antigen capsid protein L1 of quadrivalent HPV vaccine.Methods A double-antibody sandwich ELISA was used to construct the HPV vaccine specific activity detection system, using four-parameter logistic model for standard curve fitting. The method was systematically validated through tests of specificity, linearity, accuracy, intermediate precision, detection range, and method applicability.Results The HPV6/11/16/18 ELISA detection kits showed qualified specificity without cross-reactivity between different genotypes. The specific activity ELISA detection method showed good linear relationships for all types, with all coefficients of determination ≥ 0.99. The relative standard deviations (RSDs) of repeatability were ≤ 15% for all types, and RSDs of intermediate precision were ≤ 20% for all types. Within the antigen concentration range of 15.625-16 000.000 ng/mL,all average spiked recovery rates were within 98%-110%, and RSDs of spiked recovery rates for all types were ≤ 12%. The speciific activities of monovalent bulk samples and elutes from different vaccine batches all met quality standards.Conclusion The established double-antibody sandwich ELISA for specific activity detection of HPV L1 antigen has good specificity, linearity, repeatability, accuracy, and intermediate precision, and can be used for the detection of antigen specific activity in quadrivalent HPV vaccine monovalent bulk and production process control samples, providing technical guarantee for vaccine production process monitoring and final product quality evaluation.
Mucosal surface serves as the primary barrier against pathogen invasion, with 70%-90% of infections occurring on the respiratory, gastrointestinal, and female genital mucosa. Natural infection can induce local antigen-specific immune memory.Conventional injectable vaccines primarily elicit serum neutralizing antibodies and fail to establish an immune barrier mediated by secretory IgA and tissue-resident memory T/B cells at mucosal sites. In contrast, mucosal vaccines can directly target mucosal tissues, inducing local specific immune responses that block pathogen entry at the source. This review systematically describes the mechanisms of antigen recognition, uptake, and presentation across 3 major mucosal routes, analyzes the research progress, immunogenicity, and efficacy of intranasal, oral, and inhalation mucosal vaccines, and discusses safety challenges associated with mucosal vaccines. It also proposes future research directions, including novel vaccine platform development, adjuvant innovation, sequential vaccination strategies, and standardized evaluation systems, providing reference for the development and clinical application of mucosal vaccines.
In the past decade, novel biopharmaceutical medicines built on cell substrate have witnessed a remarkable surge in development. This rapid progress has brought about new and stringent requirements for safety testing. Compared with traditional detection methods, next-generation sequencing (NGS), also known as high-throughput sequencing, plays a revolutionary role in the exogenous viral detection of biological products due to its broad-spectrum detection capability and high sensitivity. This review systematically collates existing studies concerning NGS-based biosafety evaluation for biological products, with central discussion focused on core bottlenecks including technical standardization, aiming to offer reference frameworks for technical refinement and large-scale industrial implementation.
Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is the core protein in EBV latent infection, playing a critical role in various EBV-associated tumors (such as Burkitt lymphoma and nasopharyngeal carcinoma) and autoimmune diseases by maintaining the viral genome, promoting immune evasion, and facilitating cellular immortalization. This review systematically elucidates the multi-domain characteristics of EBNA1 and pathogenic molecular mechanisms, including the glycine-alanine repeat-mediated translational self-inhibition and immune evasion, the DNA-binding/dimerization domain-mediated replication and maintenance of viral genome, and the ubiquitin-specific protease 7-binding domain-mediated interference with the p53 pathway, as well as novel therapeutic strategies targeting EBNA1, including small-molecule inhibitors that disrupt its DNA-binding ability, monoclonal antibodies, compounds targeting the glycine-alanine repeat/nucleolin interaction, and the proteolysis-targeting chimera technology. Challenges faced by these therapeutic strategies in drug delivery, selectivity, and resistance, and their application prospects are also discussed.
Neisseria meningitides (Nm), a key pathogen causing invasive meningitis and sepsis, poses a serious threat to public health due to its wide epidemiological distribution and high mortality rate. Monoclonal antibodies (mAbs), with their advantages of high specificity and high affinity, demonstrate tremendous potential in the diagnosis, treatment, and prevention of Nm infections. This review systematically summarizes the epidemiological characteristics, pathogenic features, and typing basis of Nm to establish a foundation for subsequent mAb research. Focusing on target types, it elaborates on the current research status of mAbs related to serogroup B Nm bacterial proteins, serogroups ACWYX polysaccharide components, and the host complement system, confirming the main mechanism of blocking immune escape and multiple antibodies combined with complement activation. Based on existing research outcomes, conservative epitodes recognition and combination of multiple antigens have been proved to be key strategies for broad-spectrum Nm treatment. This review further analyzes current challenges in Nm research, including antigen diversity and antibody function heterogeneity, summarizes current application of mAbs in Nm infection diagnosis, passive immunity, and adjuvant treatment, and prospects the developing direction of humanized broad-spectrum antibody and multi-target combined treatment. The aim is to provide reference for further development and clinical translation of therapeutic mAbs for Nm.
Burns represent a significant global health challenge, while conventional treatments are often limited by scarce skin sources, scar formation, and suboptimal functional recovery. Stem cells, in particular mesenchymal stem cells, have emerged as key novel biological materials for promoting regenerative healing of burn wounds, owing to robust proliferative capacity, multi-lineage differentiation potential, paracrine signaling, and immunomodulatory functions. Neverthelss, low survival rates and short retention time of stem cells in the complex microenvironment of dynamic burn wounds limit their therapeutic efficacy. As stem cell delivery vehicles, hydrogels can provide three-dimensional support, maintain a moist environment, and mitigate oxidative stress and inflammation, thereby constructing a protective dynamic microenvironment that facilitates stem cell function. This review focuses on core repair mechanisms of stem cell therapy and discusses the characteristics of stem cells from different sources in burn treatment research. It further explains how hydrogel systems ultimately achieve high-quality wound repair and functional reconstruction in burns by enhancing stem cell survival, colonization, and functional persistence, as well as synergistically promoting angiogenesis, re-epithelialization, and inhibition of fibrosis. Future research should focus on optimizing stem cell sources and engineering strategies, and developing precisely matched intelligent hydrogel carriers to accelerate clinical translation.
