H1N1流感病毒在微载体培养MDCK细胞上增殖的研究

目的探索MDCK细胞在微载体上的培养条件,并研究H1N1型流感病毒在MDCK细胞上的增殖条件。方法在微载体上培养好MDCK细胞上用H1N1型流感病毒在不同的病毒感染复数(MOI)、胰酶浓度两个关键的病毒增殖条件进行流感病毒在细胞上的增殖研究。结果微载体质量浓度为6 g/L时,MDCK细胞培养密度可以达到4.5×106cells/mL。在MOI为0.05接种流感病毒,胰酶质量浓度4μg/mL,流感病毒在MDCK细胞上可获得较高的滴度。结论 MDCK细胞用微载体培养可以达到较高的细胞密度,可以作为规模化生产新型流感病毒疫苗的主要细胞基质进行进一步的研究。     

类弹性蛋白多肽的从头设计、非色谱纯化及盐效应

近年来,因病毒侵害人类每年都要蒙受巨大的经济损失和社会损失。犬肾细胞MDCK以其具有的培养容易、增殖快、流感病毒感染效率高等特点,成为适用于流感病毒疫苗生产的重要细胞系之一。以MDCK细胞为研究对象,在自制无血清培养基中成功实现了MDCK细胞从有血清培养到无血清培养的驯化;并通过单细胞悬浮培养驯化过程实现了MDCK细胞的无血清单细胞悬浮培养,获得了适于无血清单细胞悬浮生长的ssf-MDCK细胞株,无血清单细胞悬浮批培养最大活细胞密度可达3.81×106 cells/mL,最大比生长速率可达0.056 h?     

细胞密度和营养供给对H1N1流感病毒产率的影响

探究细胞培养生产流感病毒过程中,高细胞密度引起低单位细胞病毒产率(Svy)的原因及找到解决方法。通过增加微载体浓度以及换液操作获得较高的细胞密度;考察了感染时细胞密度(CCI)和病毒感染用维持培养基对病毒产量和单位细胞病毒产率的影响。在12.6 g/L微载体培养过程中,通过换液操作,可获得高细胞密度,达到1.47×107 cells/m L。在CCI为1×107cells/m L条件时,选择合适的维持培养基,其Svy最高达到5.14×103 virions/cell,比同等条件下用DMEM维持培养基的Svy值提高了近一倍。高密度培养MDCK细胞生产流感病毒时,充分考虑不同阶段的培养条件和营养需求,可以提高细胞密度和单位细胞病毒产率,进而提高流感病毒的产量。该研究结果为工业化生产流感病毒疫苗提供了基础数据。     

适于无血清贴壁培养的抗凋亡宿主细胞系CHO-IVB2的构建

应用无血清培养基培养CHO细胞时 ,由于没有血清提供各种贴壁因子 ,细胞以悬浮的方式生长。在实际的大规模细胞培养中 ,CHO细胞往往以贴壁方式培养 ,要么贴壁于悬浮的微载体中 ,要么贴壁于固定的聚酯盘状介质或中空纤维中 ,而很少直接悬浮于培养基中。在无血清培养基中 ,Vitronectin单一组分可以促使CHO细胞的贴壁和扩增。通过双表达Igf_1和Bcl_2基因 ,已经构建了可以在无蛋白培养基IMEM中抗凋亡生长的细胞株CHO_IB3。在此基础上 ,构建了可以同时表达Igf-1、Vitronectin和Bcl-2三个蛋白的三顺反子表达载体pCI-NII-IVB。将该载体转染于CHO-dhfr^- 细胞中 ,构建了一个细胞株CHO-IVB2。该细胞株可以在无蛋白培养基中抗凋亡生长 ,适于以贴壁的方式大规模培养 ,用于大量生产外源目的蛋白.     

适于无血清贴壁培养的抗凋亡宿主细胞系CHO-IVB2的构建

应用无血清培养基培养CHO细胞时,由于没有血清提供各种贴壁因子,细胞以悬浮的方式生长。在实际的大规模细胞培养中,CHO细胞往往以贴壁方式培养,要么贴壁于悬浮的微载体中,要么贴壁于固定的聚酯盘状介质或中空纤维中,而很少直接悬浮于培养基中。在无血清培养基中,Vitronectin单一组分可以促使CHO细胞的贴壁和扩增。通过双表达lgf-1和Bcl-2基因,已经构建了可以在无蛋白培养基IMEM中抗凋亡生长的细胞株CHO-IB3。在此基础上,构建了可以同时表达Igf-1、Vitronectin和Bcl-2三个蛋白的三顺反子表达载体pCI—NII—IVB。将该载体转染于CHO—dhfr^-细胞中,构建了一个细胞株CHO—IVB2。该细胞株可以在无蛋白培养基中抗凋亡生长,适于以贴壁的方式大规模培养,用于大量生产外源目的蛋白。     

MDCK细胞的悬浮驯化及初步应用

目的：驯化MDCK细胞使之适应悬浮培养,以之作为生产流感病毒疫苗的介质,为以细胞代替鸡胚制备流感病毒疫苗提供保证。方法：通过直接法和间接法分别驯化MDCK细胞,放大培养能悬浮生长的MDCK细胞,并以之作为介质培养流感病毒。结果：获得了能悬浮培养的MDCK细胞,其在悬浮条件下生长良好;以之作为载体培养流感病毒,可获得较高产量的病毒。结论：建立了悬浮培养的MDCK细胞,以之作为载体培养流感病毒可获得较高病毒滴度,为细胞培养生产流感病毒疫苗奠定了基础。     

MDCK细胞微载体培养条件优化研究

研究细胞接种量、搅拌转速和微载体浓度对MDCK细胞微载体培养时的影响,以合理优化MDCK细胞微载体培养最大增殖时期的最优条件,对疫苗和病毒分离具有重要意义,以期达到在疫苗和病毒分离领域提高生产效率。采用微载体培养MDCK细胞,在不同搅拌转速、微载体浓度和细胞接种量进行培养,每隔24 h取样计数,确定最优的培养条件。结果表明,细胞接种量在20个/球、搅拌转速45 r/min和载体浓度在2 g/L时,MDCK细胞的增殖较快,细胞密度较大,细胞的密度最大可达15.6×106个/mL,适合MDCK细胞增殖生长。     

VERO细胞生物反应器放大培养初探

目的:研究用生物反应器放大进行Vero细胞微载体培养,实现生物反应器之间Veto细胞放大培养.方法:5L微载体生物反应器以10g/L微载体浓度培养Vero细胞,96h时经漂洗、消化、接种于30L微载体生物反应器,实现放大后的30L微载体生物反应器细胞怏速增殖,期间对不同时期的微载体细胞进行细胞计数、细胞代谢分析和形态观察.结果:5L生物反应器细胞经过96h灌注培养,平均细胞密度达到7.81×10~6cells/mL.5L微载体细胞放大到30L微载体生物反应器,平均细胞收获率为32.3%;放大到30L生物反应器后经过144h培养,细胞密度达到9.19×10~6cells/mL;放大后的细胞代谢途径依然以葡萄糖氧化代谢乳酸为主.结论:生物反应器由5L到30L进行Veto细胞放大培养是可行的.     

血清浓度及溶氧对培养rCHO细胞生产尿激酶原的影响

在30L搅拌式反应器中用多孔微载体培养分泌尿激酶原的DNA重组中国仓鼠卵巢细胞(rCHO),研究了血清浓度及溶氧对细胞生长和表达的影响.结果表明,在2×105/ml低密度接种条件下,使用低(无)血清培养基会延长细胞生长延滞期并降低比生长速率,而细胞密度大于106/ml时,血清浓度对细胞生长和产物表达的影响没有显著差别.溶氧(DO)维持在20%～45%时,对细胞表达产物和葡萄糖代谢无明显影响,但溶氧降至7%～9%时,细胞表达水平明显降低,葡萄糖代谢转化为乳酸的比例上升.     

微载体灌注培养制备Vero细胞狂犬病疫苗

本文研究在生物反应器中用微载体连续灌注培养Vero细胞生产狂犬病毒制备技术.在5L体积的生物反应器中,加入含10g/L微载体的199培养基,接种Vero细胞至细胞浓度达到1×105/mL,培养7d后细胞可生长至6～7×106/mL,然后以感染复数(MOI)为0.01接种狂犬病毒VaG株,接毒后24h开始收获,连续收获12d左右,收获的病毒滴度范围在6.0～8.5log LD50/mL,收获的病毒原液经浓缩、灭活和纯化等步骤制备成疫苗,各项质量指标均达到<中国生物制品规程>2000年版要求.实验表明,用生物反应器微载体灌注培养制备人用Vero细胞狂犬病疫苗小试工艺可行.     

Production of cell culture (MDCK) derived live attenuated influenza vaccine (LAIV) in a fully disposable platform process

The majority of influenza vaccines are manufactured using embryonated hens' eggs. The potential occurrence of a pandemic outbreak of avian influenza might reduce or even eliminate the supply of eggs, leaving the human population at risk. Also, the egg‐based production technology is intrinsically cumbersome and not easily scalable to provide a rapid worldwide supply of vaccine. In this communication, the production of a cell culture (Madin‐Darby canine kidney (MDCK)) derived live attenuated influenza vaccine (LAIV) in a fully disposable platform process using a novel Single Use Bioreactor (SUB) is presented. The cell culture and virus infection was maintained in a disposable stirred tank reactor with PID control of pH, DO, agitation, and temperature, similar to traditional glass or stainless steel bioreactors. The application of this technology was tested using MDCK cells grown on microcarriers in proprietary serum free medium and infection with 2006/2007 seasonal LAIV strains at 25–30 L scale. The MDCK cell growth was optimal at the agitation rate of 100 rpm. Optimization of this parameter allowed the cells to grow at a rate similar to that achieved in the conventional 3 L glass stirred tank bioreactors. Influenza vaccine virus strains, A/New Caledonia/20/99 (H1N1 strain), A/Wisconsin/67/05 (H3N2 strain), and B/Malaysia/2506/04 (B strain) were all successfully produced in SUB with peak virus titers ≥8.6 log₁₀ FFU/mL. This result demonstrated that more than 1 million doses of vaccine can be produced through one single run of a small bioreactor at the scale of 30 L and thus provided an alternative to the current vaccine production platform with fast turn‐around and low upfront facility investment, features that are particularly useful for emerging and developing countries and clinical trial material production. Biotechnol. Bioeng. 2010;106: 906–917. © 2010 Wiley Periodicals, Inc.     

MDCK and Vero cells for influenza virus vaccine production: a one-to-one comparison up to lab-scale bioreactor cultivation

Over the last decade, adherent MDCK (Madin Darby canine kidney) and Vero cells have attracted considerable attention for production of cell culture-derived influenza vaccines. While numerous publications deal with the design and the optimization of corresponding upstream processes, one-to-one comparisons of these cell lines under comparable cultivation conditions have largely been neglected. Therefore, a direct comparison of influenza virus production with adherent MDCK and Vero cells in T-flasks, roller bottles, and lab-scale bioreactors was performed in this study. First, virus seeds had to be adapted to Vero cells by multiple passages. Glycan analysis of the hemagglutinin (HA) protein showed that for influenza A/PR/8/34 H1N1, three passages were sufficient to achieve a stable new N-glycan fingerprint, higher yields, and a faster increase to maximum HA titers. Compared to MDCK cells, virus production in serum-free medium with Vero cells was highly sensitive to trypsin concentration. Virus stability at 37 °C for different virus strains showed differences depending on medium, virus strain, and cell line. After careful adjustment of corresponding parameters, comparable productivity was obtained with both host cell lines in small-scale cultivation systems. However, using these cultivation conditions in lab-scale bioreactors (stirred tank, wave bioreactor) resulted in lower productivities for Vero cells.     

Production of influenza H1N1 vaccine from MDCK cells using a novel disposable packed-bed bioreactor

A process for human influenza H1N1 virus vaccine production from Madin–Darby canine kidney (MDCK) cells using a novel packed-bed bioreactor is described in this report. The mini-bioreactor was used to study the relationship between cell density and glucose consumption rate and to optimize the infection parameters of the influenza H1N1 virus (A/New Caledonia/20/99). The MDCK cell culture and virus infection were then monitored in a disposable perfusion bioreactor (AmProtein Current Perfusion Bioreactor) with proportional–integral–derivative control of pH, dissolved O₂ (DO), agitation, and temperature. During 6 days of culture, the total cell number increased from 2.0?×?10⁹ to 3.2?×?10¹⁰ cells. The maximum virus titers of 768 hemagglutinin units/100 μL and 7.8?×?10⁷ 50 % tissue culture infectious doses/mL were obtained 3 days after infection. These results demonstrate that using a disposable perfusion bioreactor for large-scale cultivation of MDCK cells, which allows for the control of DO, pH, and other conditions, is a convenient and stable platform for industrial-scale production of influenza vaccines.     

Serum-Free Suspension Culture of MDCK Cells for Production of Influenza H1N1 Vaccines

Development of serum-free suspension cell culture processes is very important for influenza vaccine production. Previously, we developed a MDCK suspension cell line in a serum-free medium. In the present study, the growth kinetics of suspension MDCK cells and influenza virus production in the serum-free medium were investigated, in comparison with those of adherent MDCK cells in both serum-containing and serum-free medium. It was found that the serum-free medium supported the stable subculture and growth of both adherent and suspension cells. In batch culture, for both cell lines, the growth kinetics in the serum-free medium was comparable with those in the serum-containing medium and a commercialized serum-free medium. In the serum-free medium, peak viable cell density (VCD), haemagglutinin (HA) and median tissue culture infective dose (TCID₅₀) titers of the two cell lines reached 4.51×10⁶ cells/mL, 2.94Log₁₀(HAU/50 μL) and 8.49Log₁₀(virions/mL), and 5.97×10⁶ cells/mL, 3.88Log₁₀(HAU/50 μL), and 10.34Log₁₀(virions/mL), respectively. While virus yield of adherent cells in the serum-free medium was similar to that in the serum-containing medium, suspension culture in the serum-free medium showed a higher virus yield than adherent cells in the serum-containing medium and suspension cells in the commercialized serum-free medium. However, the percentage of infectious viruses was lower for suspension culture in the serum-free medium. These results demonstrate the great potential of this suspension MDCK cell line in serum-free medium for influenza vaccine production and further improvements are warranted.     

Production of inactivated influenza H5N1 vaccines from MDCK cells in serum-free medium

Background

Highly pathogenic influenza viruses pose a constant threat which could lead to a global pandemic. Vaccination remains the principal measure to reduce morbidity and mortality from such pandemics. The availability and surging demand for pandemic vaccines needs to be addressed in the preparedness plans. This study presents an improved high-yield manufacturing process for the inactivated influenza H5N1 vaccines using Madin-Darby canine kidney (MDCK) cells grown in a serum-free (SF) medium microcarrier cell culture system.

Principal Finding

The current study has evaluated the performance of cell adaptation switched from serum-containing (SC) medium to several commercial SF media. The selected SF medium was further evaluated in various bioreactor culture systems for process scale-up evaluation. No significant difference was found in the cell growth in different sizes of bioreactors studied. In the 7.5 L bioreactor runs, the cell concentration reached to 2.3×10⁶ cells/mL after 5 days. The maximum virus titers of 1024 Hemagglutinin (HA) units/50 µL and 7.1±0.3×10⁸ pfu/mL were obtained after 3 days infection. The concentration of HA antigen as determined by SRID was found to be 14.1 µg/mL which was higher than those obtained from the SC medium. A mouse immunogenicity study showed that the formalin-inactivated purified SF vaccine candidate formulated with alum adjuvant could induce protective level of virus neutralization titers similar to those obtained from the SC medium. In addition, the H5N1 viruses produced from either SC or SF media showed the same antigenic reactivity with the NIBRG14 standard antisera.

Conclusions

The advantages of this SF cell-based manufacturing process could reduce the animal serum contamination, the cost and lot-to-lot variation of SC medium production. This study provides useful information to manufacturers that are planning to use SF medium for cell-based influenza vaccine production.     

Abortive Infection of L Cells by Influenza B Virus: Defect in Bud Formation

Host-dependent restriction of influenza B virus replication in L cells was analysed in comparison with productive infection in MDCK or 1–5C-4 cells. The synthesis and intracellular distribution of virus-specific proteins and the production of cytoplasmic ribonucleoproteins in nonpermissive L cells were similar to those in permissive MDCK cells. However, an electron microscopic study of infected L cells showed neither extracellular virions nor budding virus particles on the cell surface, in contrast to MDCK cells which produced numerous virus particles. PAGE analysis of the plasma membrane isolated from the cells demonstrated no significant difference in the composition of viral polypeptides between permissive 1-5C-4 and nonpermissive L cells. It was noted that the abortiveness of influenza B virus infection in L cells may be due to a defect in host cell function involved in the initiation of virus budding.     

Production of canine adenovirus type 2 in serum-free suspension cultures of MDCK cells

The potential of adherent Madin Darby Canine Kidney (MDCK) cells for the production of influenza viruses and canine adenovirus type 2 (CAV-2) for vaccines or gene therapy approaches has been shown. Recently, a new MDCK cell line (MDCK.SUS2) that was able to grow in suspension in a fully defined system was established. In this work, we investigated whether the new MDCK.SUS2 suspension cell line is suitable for the amplification of CAV-2 under serum-free culture conditions. Cell growth performance and CAV-2 production were evaluated in three serum-free media: AEM, SMIF8, and EXCELL MDCK. CAV-2 production in shake flasks was maximal when AEM medium was used, resulting in an amplification ratio of infectious particles (IP) of 142 IP out/IP in and volumetric and cell-specific productivities of 2.1?×?10⁸ IP/mL and 482 IP/cell, respectively. CAV-2 production was further improved when cells were cultivated in a 0.5-L stirred tank bioreactor. To monitor infection and virus production, cells were analyzed by flow cytometry. A correlation between the side scatter measurement and CAV-2 productivity was found, which represents a key feature to determine the best harvesting time during process development of gene therapy vectors that do not express reporter genes. This work demonstrates that MDCK.SUS2 is a suitable cell substrate for CAV-2 production, constituting a step forward in developing a production process transferable to industrial scales. This could allow for the production of high CAV-2 titers either for vaccination or for gene therapy purposes.     

犬肾细胞MDCK无血清贴壁及单细胞悬浮培养

旨在挖掘用于鉴定金黄色葡萄球菌的高特异性靶点及其PCR检测引物。采用C++语言编程,以金黄色葡萄球菌Staphylococcus aureus MRSA 252基因组编码序列为对象,对2 656个可编码区进行分析,获得特异性靶点序列,并设计PCR扩增引物。对包括葡萄球菌属11个种及其他细菌属在内的共计137株细菌验证引物特异性,筛选获得9个DNA序列,并设计了4对引物。经验证2对引物的特异性较好,其中引物SA3的基因组DNA检测限为13.7 fg/μL,菌体检测限为9.25×102 CFU/mL。结果验证