Cell Culture-based Vaccine Research Articles

Antibody response to sequential vaccination with cell culture, recombinant, or egg-based influenza vaccines among U.S. adults

ABSTRACT The immune response to inactivated influenza vaccines (IIV) is influenced by multiple factors, including hemagglutinin content and egg-based manufacturing. Only two US-licensed vaccines are manufactured without egg passage: cell culture-based inactivated vaccine (ccIIV) and recombinant vaccine (RIV). We conducted a randomized open-label trial in central Wisconsin during the 2018–19 and 2019–20 seasons to compare immunogenicity of sequential vaccination. Participants 18–64 years old were randomized 1:1:1 to receive RIV, ccIIV or IIV in strata defined by number of influenza vaccine doses in the prior 3 years. They were revaccinated with the same product in year two. Paired serum samples were tested by hemagglutination inhibition against egg-adapted and cell-grown vaccine viruses. Serologic endpoints included geometric mean titer (GMT), mean fold rise, and percent seroconversion. There were 373 participants randomized and vaccinated in 2018–19; 332 were revaccinated in 2019–20. In 2018–19, RIV and ccIIV were not more immunogenic than IIV against A/H1N1. The post-vaccination GMT against the cell-grown 3C.2a A/H3N2 vaccine virus was higher for RIV vs IIV (p = .001) and RIV vs ccIIV (p = .001). The antibody response to influenza B viruses was similar across study arms. In 2019–20, GMT against the cell-grown 3C.3a A/H3N2 vaccine virus was higher for RIV vs IIV (p = .03) and for RIV vs ccIIV (p = .001). RIV revaccination generated significantly greater backboosting to the antigenically distinct 3C.2a A/H3N2 virus (2018–19 vaccine strain) compared to ccIIV or IIV. This study adds to the evidence that RIV elicits a superior immunologic response against A/H3N2 viruses compared to other licensed influenza vaccine products.

Animal Cell Lines as Expression Platforms in Viral Vaccine Production: A Post Covid-19 Perspective.

Vaccines are considered the most effective tools for preventing diseases. In this sense, with the Covid-19 pandemic, the effects of which continue all over the world, humanity has once again remembered the importance of the vaccine. Also, with the various epidemic outbreaks that occurred previously, the development processes of effective vaccines against these viral pathogens have accelerated. By these efforts, many different new vaccine platforms have been approved for commercial use and have been introduced to the commercial landscape. In addition, innovations have been made in the production processes carried out with conventionally produced vaccine types to create a rapid response to prevent potential epidemics or pandemics. In this situation, various cell lines are being positioned at the center of the production processes of these new generation viral vaccines as expression platforms. Therefore, since the main goal is to produce a fast, safe, and effective vaccine to prevent the disease, in addition to existing expression systems, different cell lines that have not been used in vaccine production until now have been included in commercial production for the first time. In this review, first current viral vaccine types in clinical use today are described. Then, the reason for using cell lines, which are the expression platforms used in the production of these viral vaccines, and the general production processes of cell culture-based viral vaccines are mentioned. Also, selection parameters for animal cell lines as expression platforms in vaccine production are explained by considering bioprocess efficiency and current regulations. Finally, all different cell lines used in cell culture-based viral vaccine production and their properties are summarized, with an emphasis on the current and future status of cell cultures in industrial viral vaccine production.

Intensified Influenza Virus Production in Suspension HEK293SF Cell Cultures Operated in Fed-Batch or Perfusion with Continuous Harvest.

Major efforts in the intensification of cell culture-based viral vaccine manufacturing focus on the development of high-cell-density (HCD) processes, often operated in perfusion. While perfusion operations allow for higher viable cell densities and volumetric productivities, the high perfusion rates (PR) normally adopted-typically between 2 and 4 vessel volumes per day (VVD)-dramatically increase media consumption, resulting in a higher burden on the cell retention device and raising challenges for the handling and disposal of high volumes of media. In this study, we explore high inoculum fed-batch (HIFB) and low-PR perfusion operations to intensify a cell culture-based process for influenza virus production while minimizing media consumption. To reduce product retention time in the bioreactor, produced viral particles were continuously harvested using a tangential flow depth filtration (TFDF) system as a cell retention device and harvest unit. The feeding strategies developed-a hybrid fed-batch with continuous harvest and a low-PR perfusion-allowed for infections in the range of 8-10 × 106 cells/mL while maintaining cell-specific productivity comparable to the batch control, resulting in a global increase in the process productivity. Overall, our work demonstrates that feeding strategies that minimize media consumption are suitable for large-scale influenza vaccine production.

Application of bioreactor technology for cell culture-based viral vaccine production: Present status and future prospects

Bioreactors are widely used in cell culture-based viral vaccine production, especially during the coronavirus disease 2019 (COVID-19) pandemic. In this context, the development and application of bioreactors can provide more efficient and cost-effective vaccine production to meet the global vaccine demand. The production of viral vaccines is inseparable from the development of upstream biological processes. In particular, exploration at the laboratory-scale is urgently required for further development. Therefore, it is necessary to evaluate the existing upstream biological processes, to enable the selection of pilot-scale conditions for academic and industrial scientists to maximize the yield and quality of vaccine development and production. Reviewing methods for optimizing the upstream process of virus vaccine production, this review discusses the bioreactor concepts, significant parameters and operational strategies related to large-scale amplification of virus. On this basis, a comprehensive analysis and evaluation of the various process optimization methods for the production of various viruses (SARS-CoV-2, Influenza virus, Tropical virus, Enterovirus, Rabies virus) in bioreactors is presented. Meanwhile, the types of viral vaccines are briefly introduced, and the established animal cell lines for vaccine production are described. In addition, it is emphasized that the co-development of bioreactor and computational biology is urgently needed to meet the challenges posed by the differences in upstream production scales between the laboratory and industry.

Effectiveness of cell culture-based influenza vaccines compared with egg-based vaccines: What does the literature say?

IntroductionInfluenza vaccination is an effective way of reducing the burden of seasonal influenza. Chicken egg embryos are the most common source of influenza vaccines, but cell culture production has emerged as an alternative that could be advantageous. This article reviews the available literature on the efficacy/effectiveness of cell culture-based influenza vaccines compared with egg-based vaccines.MethodsWe conducted a review of the actual literature and analyzed those studies comparing the effectiveness of cell culture-based and egg-based vaccines in the last ten years.ResultsEight studies were analyzed; 1 was a clinical trial and 7 were retrospective cohort studies. The clinical trial found no significant differences in the efficacy of both vaccines with respect to placebo. The results of the observational studies were inconsistent and relative effectiveness varied among studies, even though most were performed during the same season, and in some cases, in the same region and using the same data records. Furthermore, in most studies, the comparisons between vaccines were not statistically significant.ConclusionsThere is insufficient evidence that cell culture-based vaccines are superior to egg-based vaccines in terms of efficacy/effectiveness.

Adaptation and characterization of Anatid herpesvirus 1 in different permissible cell lines

Duck viral enteritis is an acute, contagious infection of Anatidae family members. The disease is caused by Anatid herpesvirus 1 (AnHV-1). The infection of AnHV-1 is controlled by vaccination to the flock with chick embryo adapted attenuated vaccine in developed countries. However, its economic impact in developing countries is substantial and there is a need to understand the cell culture spectrum of the virus to produce its vaccine on a mass scale. In the present study, the permissivity of AnHV-1 for different cells was analyzed. The AnHV-1 showed enhanced replication following its serial passage in CEF, DF-1, Vero, MDCK, and QT-35 cells. The characteristic cytopathic effect (CPE) of rounding and clumping of cells were observed in CEF, DF-1, Vero, and QT-35 cell lines. The infectivity and viral replication were highest in CEF, DF-1, Vero, and QT-35 cells. In contrast, the results suggested that MDCK cells are less permissive for AnHV-1 infection with negligible CPE and reduced viral replication. Heterologous cell culture systems other than chicken embryo fibroblasts to adapted live vaccine viruses will provide a system devoid of other avian infectious agents. Moreover, it can be used for the propagation and cultivation of AnHV-1 vaccine strain for developing cell culture-based vaccines with high titer and could be an economical alternative for the existing options.

RNA-assisted self-assembly of monomeric antigens into virus-like particles as a recombinant vaccine platform

Representing highly ordered repetitive structures of antigen macromolecular assemblies, virus-like particles (VLPs) serve as a high-priority vaccine platform against emerging viral infections, as alternatives to traditional cell culture-based vaccines. RNAs can function as chaperones (Chaperna) and are extremely effective in promoting protein folding. Beyond their canonical function as translational adaptors, tRNAs may moonlight as chaperones for the kinetic control of macromolecular antigen assembly. Capitalizing on genomic RNA co-assembly in infectious virions, we present the first report of a biomimetic assembly of viral capsids that was assisted by non-viral host RNAs into genome-free, non-infectious empty particles. Here, we demonstrate the assembly of bacterially-produced soluble norovirus VP1 forming VLPs (n = 180) in vitro. A tRNA-interacting domain (tRID) was genetically fused with the VP1 capsid protein, as a tRNA docking tag, in the bacterial host to transduce chaperna function for de novo viral antigen folding. tRID/tRNA removal prompted the in vitro assembly of monomeric antigens into highly ordered repetitive structures that elicited robust protective immune responses after immunization. The chaperna-based assembly of monomeric antigens will impact the development and deployment of VLP vaccines for emerging and re-emerging viral infections.

2751. Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD (PAIVED): Methods

BackgroundMost influenza vaccines come from inactivated virus grown in egg culture, and studies suggest that egg-adapted virus may have decreased immunogenicity in humans for certain influenza A strains. Cell culture-based and recombinant vaccines may be more immunogenic, but comparative studies are lacking. We are conducting a randomized, controlled trial of 3 FDA-licensed influenza vaccines (cell culture, recombinant, and egg culture) to assess differences in immunogenicity and effectiveness in adults.MethodsA total of 10,650 eligible adults will be individually randomized 1:1:1 (cell culture, recombinant, or egg-based vaccine) over 2 influenza seasons (2018–2019 and 2019–2020) at military facilities in geographically diverse locations in the US Participants who are not military recruits will report the presence or absence of ILI symptoms on a weekly basis through an automated electronic (text message or email) survey; those who experience ILI symptoms will be scheduled for two in-person visits. Military recruits who experience an ILI report will report directly to clinic and will not receive weekly surveillance reminders (Figure 1).ResultsEnrollment for year 1 of PAIVED occurred November 7 to December 31, 2018 at 5 military bases. During this season, 1,623 participants were enrolled, among whom 34% were randomized to receive cell culture vaccine, 33% to recombinant vaccine, and 33% to egg-based vaccine. The participants were 61% active military, 19% retired military, and 20% military dependents. One quarter of the participants were women, and the participants were 18–88 years old, median 26 years of age. Among the 1,559 participants with complete data, 324 (21%) experienced ILI at least once. Blood and swab samples were successfully collected at visit 1 from 93% of the participants with case-defined ILIs.ConclusionThe initial phase of PAIVED successfully enrolled and randomized 1,623 participants during the 2018/2019 influenza season. Follow-up of this season’s participants is on-going. PAIVED will apply lessons learned during the 2018/2019 influenza season to the next season’s study implementation, with the goal of enrolling more than 9,000 additional participants through increasing the number of individuals enrolled at some sites and adding new sites to the trial. Disclosures All authors: No reported disclosures.

One hundred years after the 1918 pandemic: new concepts for preparing for influenza pandemics.

In the 100 years since the influenza pandemic of 1918-1919, the most deadly event in human history, we have made substantial progress yet we remain vulnerable to influenza pandemics This article provides a brief overview of important advances in preparing for an influenza pandemic, viewed largely from the perspective of the healthcare system. We have gained insights into influenza pathogenicity, the animal reservoir and have improved global surveillance for new strains and tools for assessing the pandemic risk posed by novel strains. Public health has refined plans for severity assessment, distribution of countermeasures and nonpharmaceutical approaches. Modest improvements in vaccine technology include cell culture-based vaccines, adjuvanted vaccine and recombinant technology. Conventional infection control tools will be critical in healthcare settings. New evidence suggests that influenza virus may be present in aerosols; the contribution of airborne transmission and role of N95 respirators remains unknown. Baloxavir and pimodivir are new antivirals that may improve treatment, especially for severely ill patients. Optimal use and the risk of resistance require further study. Despite the progress in pandemic preparedness, gaps remain including important scientific questions, adequate resources and most importantly, the ability to rapidly deliver highly effective vaccines.

Influenza A virus production in a single-use orbital shaken bioreactor with ATF or TFF perfusion systems

Driven by the concept of plug-and-play cell culture-based viral vaccine production using disposable bioreactors, we evaluated an orbital shaken bioreactor (OSB) for human influenza A virus production at high cell concentration. Therefore, the OSB model SB10-X was coupled to two hollow fiber-based perfusion systems, namely, tangential flow filtration (TFF) and alternating tangential flow filtration (ATF). The AGE1.CR.pIX avian suspension cells grew to 50 × 106 cells/mL in chemically defined medium, maintaining high cell viabilities with an average specific growth rate of 0.020 h−1 (doubling time = 32 h). Maximum virus titers in the range of 3.28–3.73 log10(HA units/100 µL) were achieved, corresponding to cell-specific virus yields of 1000–3500 virions/cell and productivities of 0.5–2.2 × 1012 virions/L/d. This clearly demonstrates the potential of OSB operation in perfusion mode, as results achieved in a reference OSB batch cultivation were 2.64 log10(HA units/100 µL), 1286 virions/cell and 1.4 × 1012 virions/L/d, respectively. In summary, the SB10-X bioreactor can be operated with ATF and TFF systems, which is to our knowledge the first report regarding OSB operation in perfusion mode. Moreover, the results showed that the system is a promising cultivation system for influenza A virus vaccine production. The OSB disposable bioreactor has the potential for simplifying the scale-up from shake flasks to the large-scale bioreactor, facilitating rapid responses in the event of epidemics or pandemics.

Use of recombinant influenza vaccines expressing exogenous miRNAs for increased vaccine production

Abstract Vaccination remains the most effective means by which influenza virus infection can be controlled. Traditionally vaccine production has focused on egg-based technology. Increasingly cell culture-based vaccine production is being used to improve preparedness. Cell cultured based production methods offer significant advantages over traditional egg-based strategies by allowing (i) rapid scale-up (ii) elimination of allergic egg components and (iii) circumvention of issues relating to egg-adaption. Our aim was to improve influenza vaccines and preparedness through the establishment of mammalian cell (Vero)-based vaccines using plasmid-based recombinant flu constructs expressing exogenous miRNA19 (flu-miR19), a regulator of key host anti-viral pathways that has previously been shown to modulate influenza virus replication. We successfully rescued recombinant influenza viruses expressing miR19 using reverse genetics; validated expression of miR19 and showed increased virus replication in vitro that corresponded with increased HA titres and matrix gene expression. Knockdown of miR19 host target genes was confirmed through qRT-PCR to validate the mechanism of action. This new influenza vaccine platform is scalable and can be merged with existing production technology to offer rapid clinical translation and improve vaccine quality and production times. In summary, silencing of anti-viral host genes using a flu-miR resulted in an increase of influenza vaccine and HA antigen yield. We now plan to further augment antigen yield by propagating these viruses in enhanced Vero cell vaccine substrates.

Variable selection and parameter estimation of viral amplification in vero cell cultures dedicated to the production of a dengue vaccine.

In this study, a dynamic model of a Vero cell culture-based dengue vaccine production process is developed. The approach consists in describing the process dynamics as functions of the whole living (uninfected and infected) biomass whereas previous works are based on population balance approaches. Based on the assumption that infected biomass evolves faster than other variable, the model can be simplified using a slow-fast approximation. The structural identifiability of the model is analysed using differential algebra as implemented in the software DAISY. The model parameters are inferred from experimental datasets collected from an actual vaccine production process and the model predictive capability is confirmed both in direct and cross-validation. The model prediction shows the impact of the metabolism on virus yield and confirms observations reported in previous studies. Multi-modality and sensitivity analysis complement the parameter estimation, and allow to obtain confidence intervals on both parameters and state estimates. Finally, the model is used to compute the maximum infectious virus yield that can be obtained for different combinations of multiplicity of infection (MOI) and time of infection (TOI). © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2687, 2019.

Process intensification of EB66\xae cell cultivations leads to high-yield yellow fever and Zika virus production

A live-attenuated, human vaccine against mosquito-borne yellow fever virus has been available since the 1930s. The vaccine provides long-lasting immunity and consistent mass vaccination campaigns counter viral spread. However, traditional egg-based vaccine manufacturing requires about 12 months and vaccine supplies are chronically close to shortages. In particular, for urban outbreaks, vaccine demand can be covered rarely by global stockpiling. Thus, there is an urgent need for an improved vaccine production platform, ideally transferable to other flaviviruses including Zika virus. Here, we present a proof-of-concept study regarding cell culture-based yellow fever virus 17D (YFV) and wild-type Zika virus (ZIKV) production using duck embryo-derived EB66® cells. Based on comprehensive studies in shake flasks, 1-L bioreactor systems were operated with scalable hollow fiber-based tangential flow filtration (TFF) and alternating tangential flow filtration (ATF) perfusion systems for process intensification. EB66® cells grew in chemically defined medium to cell concentrations of 1.6 × 108 cells/mL. Infection studies with EB66®-adapted virus led to maximum YFV titers of 7.3 × 108 PFU/mL, which corresponds to about 10 million vaccine doses for the bioreactor harvest. For ZIKV, titers of 1.0 × 1010 PFU/mL were achieved. Processes were automated successfully using a capacitance probe to control perfusion rates based on on-line measured cell concentrations. The use of cryo-bags for direct inoculation of production bioreactors facilitates pre-culture preparation contributing to improved process robustness. In conclusion, this platform is a powerful option for next generation cell culture-based flavivirus vaccine manufacturing.

High-cell-density cultivations to increase MVA virus production

Increasing the yield and the productivity in cell culture-based vaccine manufacturing using high-cell-density (HCD) cultivations faces a number of challenges. For example, medium consumption should be low to obtain a very high concentration of viable host cells in an economical way but must be balanced against the requirement that accumulation of toxic metabolites and limitation of nutrients have to be avoided. HCD cultivations should also be optimized to avoid unwanted induction of apoptosis or autophagy during the early phase of virus infection. To realize the full potential of HCD cultivations, a rational analysis of the cultivation conditions of the appropriate host cell line together with the optimal infection conditions for the chosen viral vaccine strain needs to be performed for each particular manufacturing process.We here illustrate our strategy for production of the modified vaccinia Ankara (MVA) virus isolate MVA-CR19 in the avian suspension cell line AGE1.CR.pIX at HCD. As a first step we demonstrate that the adjustment of the perfusion rate strictly based on the measured cell concentration and the glucose consumption rate of cells enables optimal growth in a 0.8 L bioreactor equipped with an ATF2 system. Concentrations up to 57 × 106 cells/mL (before infection) were obtained with a viability exceeding 95%, and a maximum specific cell growth rate of 0.019 h−1 (doubling time = 36.5 h). However, not only the cell-specific MVA-CR19 virus yield but also the volumetric productivity was reduced compared to infections at conventional-cell-density (CCD).To facilitate optimization of the virus propagation phase at HCD, a larger set of feeding strategies was analyzed in small-scale cultivations using shake flasks. Densities up to 63 × 106 cells/mL were obtained at the end of the cell growth phase applying a discontinuous perfusion mode (semi-perfusion) with the same cell-specific perfusion rate as in the bioreactor (0.060 nL/(cell d)). At this cell concentration, a medium exchange at time of infection was required to obtain expected virus yields during the first 24 h after infection. Applying an additional fed-batch feeding strategy during the whole virus replication phase resulted in a faster virus titer increase during the first 36 h after infection. In contrast, a semi-continuous virus harvest scheme improved virus accumulation and recovery at a rather later stage of infection. Overall, a combination of both fed-batch and medium exchange strategies resulted in similar cell-specific virus yields as those obtained for CCD processes but 10-fold higher MVA-CR19 titers, and four times higher volumetric productivity.

Efficient and stable production of Modified Vaccinia Ankara virus in two-stage semi-continuous and in continuous stirred tank cultivation systems.

One important aim in cell culture-based viral vaccine and vector production is the implementation of continuous processes. Such a development has the potential to reduce costs of vaccine manufacturing as volumetric productivity is increased and the manufacturing footprint is reduced. In this work, continuous production of Modified Vaccinia Ankara (MVA) virus was investigated. First, a semi-continuous two-stage cultivation system consisting of two shaker flasks in series was established as a small-scale approach. Cultures of the avian AGE1.CR.pIX cell line were expanded in the first shaker, and MVA virus was propagated and harvested in the second shaker over a period of 8–15 days. A total of nine small-scale cultivations were performed to investigate the impact of process parameters on virus yields. Harvest volumes of 0.7–1 L with maximum TCID50 titers of up to 1.0×109 virions/mL were obtained. Genetic analysis of control experiments using a recombinant MVA virus containing green-fluorescent-protein suggested that the virus was stable over at least 16 d of cultivation. In addition, a decrease or fluctuation of infectious units that may indicate an excessive accumulation of defective interfering particles was not observed. The process was automated in a two-stage continuous system comprising two connected 1 L stirred tank bioreactors. Stable MVA virus titers, and a total production volume of 7.1 L with an average TCID50 titer of 9×107 virions/mL was achieved. Because titers were at the lower range of the shake flask cultivations potential for further process optimization at large scale will be discussed. Overall, MVA virus was efficiently produced in continuous and semi-continuous cultivations making two-stage stirred tank bioreactor systems a promising platform for industrial production of MVA-derived recombinant vaccines and viral vectors.

Cell Culture-based Viral Vaccines: Current Status and Future Prospects

Cell culture-based viral vaccines are used globally to immunize humans against infections. The cell culture is continuous process of developing substrates for the safe production of viral vaccines. However, increased global demand and strict safety rules for novel vaccines to control and eradicate viral diseases have forced researchers and manufacturers toward cell culture-based vaccines. The choice of cell substrate is a critical step that cannot be generalized for every vaccine formulation, therefore, manufacturers intend to optimize the required processes for particular applications. The recently established cell lines, innovative bioreactor concepts and cultivation schemes are necessary to increase the potential of vaccine production. In this review, we have focused on current cell culture-based viral vaccines and their future prospects.

Epidemiology, Impact and Control of Rabies in Nepal: A Systematic Review.

BackgroundRabies is a vaccine-preventable viral zoonosis belonging to the group of neglected tropical diseases. Exposure to a rabid animal may result in a fatal acute encephalitis if effective post-exposure prophylaxis is not provided. Rabies occurs worldwide, but its burden is disproportionately high in developing countries, including Nepal. We aimed to summarize current knowledge on the epidemiology, impact and control of rabies in Nepal.MethodsWe performed a systematic review of international and national scientific literature and searched grey literature through the World Health Organization Digital Library and the library of the National Zoonoses and Food Hygiene Research Centre, Nepal, and through searching Google and Google Scholar. Further data on animal and human rabies were obtained from the relevant Nepalese government agencies. Finally, we surveyed the archives of a Nepalese daily to obtain qualitative information on rabies in Nepal.FindingsSo far, only little original research has been conducted on the epidemiology and impact of rabies in Nepal. Per year, rabies is reported to kill about 100 livestock and 10–100 humans, while about 1,000 livestock and 35,000 humans are reported to receive rabies post-exposure prophylaxis. However, these estimates are very likely to be serious underestimations of the true rabies burden. Significant progress has been made in the production of cell culture-based anti-rabies vaccine and rabies immunoglobulin, but availability and supply remain a matter of concern, especially in remote areas. Different state and non-state actors have initiated rabies control activities over the years, but efforts typically remained focalized, of short duration and not harmonized. Communication and coordination between veterinary and human health authorities is limited at present, further complicating rabies control in Nepal. Important research gaps include the reporting biases for both human and animal rabies, the ecology of stray dog populations and the true contribution of the sylvatic cycle.InterpretationBetter data are needed to unravel the true burden of animal and human rabies. More collaboration, both within the country and within the region, is needed to control rabies. To achieve these goals, high level political commitment is essential. We therefore propose to make rabies the model zoonosis for successful control in Nepal.

Bioreactors for high cell density and continuous multi-stage cultivations: options for process intensification in cell culture-based viral vaccine production.

With an increasing demand for efficacious, safe, and affordable vaccines for human and animal use, process intensification in cell culture-based viral vaccine production demands advanced process strategies to overcome the limitations of conventional batch cultivations. However, the use of fed-batch, perfusion, or continuous modes to drive processes at high cell density (HCD) and overextended operating times has so far been little explored in large-scale viral vaccine manufacturing. Also, possible reductions in cell-specific virus yields for HCD cultivations have been reported frequently. Taking into account that vaccine production is one of the most heavily regulated industries in the pharmaceutical sector with tough margins to meet, it is understandable that process intensification is being considered by both academia and industry as a next step toward more efficient viral vaccine production processes only recently. Compared to conventional batch processes, fed-batch and perfusion strategies could result in ten to a hundred times higher product yields. Both cultivation strategies can be implemented to achieve cell concentrations exceeding 107 cells/mL or even 108 cells/mL, while keeping low levels of metabolites that potentially inhibit cell growth and virus replication. The trend towards HCD processes is supported by development of GMP-compliant cultivation platforms, i.e., acoustic settlers, hollow fiber bioreactors, and hollow fiber-based perfusion systems including tangential flow filtration (TFF) or alternating tangential flow (ATF) technologies. In this review, these process modes are discussed in detail and compared with conventional batch processes based on productivity indicators such as space-time yield, cell concentration, and product titers. In addition, options for the production of viral vaccines in continuous multi-stage bioreactors such as two- and three-stage systems are addressed. While such systems have shown similar virus titers compared to batch cultivations, keeping high yields for extended production times is still a challenge. Overall, we demonstrate that process intensification of cell culture-based viral vaccine production can be realized by the consequent application of fed-batch, perfusion, and continuous systems with a significant increase in productivity. The potential for even further improvements is high, considering recent developments in establishment of new (designer) cell lines, better characterization of host cell metabolism, advances in media design, and the use of mathematical models as a tool for process optimization and control.

The PBS-12SF Cell Line: Development of an Alternative Cell Line for Influenza Vaccine Production

Influenza viruses cause global seasonal epidemics with the potential to cause widespread illness and mortality. Vaccination is the single best approach to prevent serious illness caused by influenza infection; however, the current egg-based vaccination technology possesses many drawbacks despite being a robust method for over 60 years. Cell culture-based vaccine production systems possess many advantages over the current method. Over the last ten years, our research group has developed and improved upon an immortalized chick embryo cell line that has shown promise as a possibility for influenza vaccine production. The purpose of this short communication is to briefly review the development of cell lines to produce influenza vaccines, focusing on our group’s work with the PBS-1 and PBS-12SF lines.

Antibody Response of Dogs to Ethiorab Rabies Vaccine

Rabies is 100% fatal, but it is preventable. More than 95% of human rabies cases occur in improperly treated individuals. This is partly due to the fact that modern post-exposure rabies prophylaxis is expensive and therefore not readily available in many endemic regions. Nervous tissue vaccine has been in use for more than 100 yrs. These vaccines have now been superseded in purity, potency, immunogenicity and safety. The efficacy and immunogenicity of inactivated tissue culture vaccine, produced in Ethiopia was evaluated. Twelve experimental dogs from local breed were duly conditioned during a quarantine period and assigned to two groups randomly. Animals in group I (cases) were vaccinated subcutaneously with 1 ml of our experimental vaccine. Dogs in group II served as non-vaccinated controls. The immune response of each dog was monitored for 120 days. On the day 120 after final sampling, all dogs were challenged in the masseter muscle with a rabies street virus of canine origin. To evaluate the titer of the rabies virus neutralizing antibodies (VNA), sera were analyzed by Fluorescent Antibody Virus Neutralization (FAVN) Test. Geometric Mean Titers (GMT) to rabies virus was determined at days 7, 15, 21, 30, 60, 90 and 120. Geometric mean titers were equal to 1.59, 1.73, 2.19, 3.58, 3.17, 3.35 and 3.56 IU/ml respectively. All dogs showed VNA titers higher than the 0.5 IU/ml mandated WHO recommended threshold. 83.3% vaccinated dogs, survived the challenge virus. In contrast, all dogs in the control (non-vaccinated group), developed rabies and died. This study indicated cell culture-based anti-rabies vaccine manufactured in Ethiopia is efficacious and immunogenic.