The process for registration of biologic products is lengthy due to the high number of studies and data required by the health authorities. However, with the COVID-19 pandemic, and the urgent need for an alternative, the authorities reduce the time for registering new products with the challenge of maintaining all the necessary reliable standards. The objective of this paper is to compare the regulatory requirements for biologics in Brazil and the European Union in the context of the pandemic and evaluate the background differences in regulations before and after the emergency. The searches were conducted in the databases of EMA and Anvisa and the results were assessed for type of document/product, regulatory scope/process step, effectiveness, and year of publication/update. Both regulators foresaw the route of registration for emergency use and followed international standards, with strict requirements for quality, safety, and efficacy. After the end of the health emergency, while EMA gradually phased out the emergency regulations, Anvisa withdrew them. It was observed that the challenges faced by the Brazilian authority and industries were related to the lack of a centralized health monitoring system. The regulators were overall aligned in the approaches during the pandemic and both had a regulatory emphasis on vaccines but the measures taken after its end differed. The main difference observed was the slower phase-out and the adoption of lessons learned strategy in the EU, which should be learning points for Anvisa if targeting a continuous readiness strategy for health emergencies.
The International Alliance for Biological Standardization (IABS), in collaboration with the World Organization for Animal Health (WOAH) convened a hybrid meeting on 22-23 October 2024 at the WOAH Headquarters (HQ) in Paris, France to discuss the global state of vaccination and surveillance for high pathogenicity avian influenza (HPAI) in poultry. The primary objective of the meeting was to advance vaccination acceptance to both control virus spread and reduce disease. Vaccination is increasingly recognized as a tool to complement biosecurity, movement controls and stamping-out of infected flocks. However, concerns persist regarding the risk of undetected, sustained transmission (silent infection) in vaccinated flocks as a result of inadequate surveillance. This has contributed to both vaccination hesitancy and trade barriers. The meeting aimed to assess the current state of the art regarding HPAI surveillance programs in vaccinated populations and their effectiveness. Representatives of multiple stakeholders were invited to share their experiences and perspectives on the use of vaccination and accompanying surveillance to control the growing H5N1 panzootic and its global impact. Several conclusions and recommendations emerged as essential to advancing the acceptance of vaccination strategies. These included (1) the utility of quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) as a sensitive, specific and economical tool to detect virus in vaccinated populations, (2) regular testing of dead birds within a flock as a highly effective method for early detection of outbreaks in vaccinated flocks and demonstrating freedom from infection and, (3) the importance of collecting information on circulating field strains in the selection of candidate vaccine antigens to ensure adequate efficacy. Testing sentinel birds was deemed less effective for surveillance and serological testing of vaccinated birds was considered more useful for assessing immunity levels than for determining the infection status of a flock. There was broad agreement on the need to standardize surveillance outcomes in terms of accepted confidence levels to promote safe and fair trade. However, it was acknowledged that context and pragmatic considerations will shape the development of situation specific plans, which must be statistically valid, scientifically sound, economically feasible and operationally sustainable for both governments and industry. Concomitantly, it was recommended that trade policies tied to vaccination and surveillance should be based solely on science and risks. To this end, enforcement of existing international rules and resolution of disputes are considered a shared responsibility. Peer reviewed publications were proposed as a central mechanism for developing the stronger guidelines needed to facilitate fair trade agreements and enable implementation of global vaccination programs. Rapid dissemination of information, consistent messaging and exchange of virus isolates were also seen as critical for coordinating an effective global response to controlling HPAI.
Antibody-dependent cell-mediated cytotoxicity (ADCC) is one of the mechanisms of action of therapeutic monoclonal antibodies (mAbs). This mechanism of action is often enhanced either through Fc mutagenesis or glycoengineering. However, certain mAbs exhibit undesirable side effects in patients due to these structural modifications for ADCC enhancement. In this study, instead of modifying the antibody structure through Fc engineering, we explored a formulation-based antioxidant treatment strategy to preserve Fc effector function and possible effects on ADCC activity. The efficacy of this approach was investigated using Rituximab (RmAb) biosimilar. We specifically focused on FcγRIIIa-mediated ADCC of RmAb, as it represents a key effector pathway impacted by Fc stability and post-translational modifications. Our results showed that affinity constants measured using surface plasmon resonance (SPR) exhibited only minor changes in presence of anti-oxidants. An in vitro ADCC reporter assay was used to evaluate FcγRIIIa-mediated effector function, serving as a surrogate assay. The ADCC reporter assay indicated modest within-run shifts in EC50 values, consistent with preservation of FcγRIIIa-mediated signaling under identical assay conditions. The potential of all anti-oxidants was demonstrated using DPPH radical scavenging assay. Further, investigations related to peptide mapping revealed that the addition of anti-oxidants prevented deamidation in asparagine and glutamine residues. We hypothesize that, these effects may be associated with a reduction in pH and the dielectric constant of formulation buffer by the addition of anti-oxidants. Thus, the addition of anti-oxidants to the mAb formulation prevented unfavorable modifications of amino acids and aided in the optimum effector function of Rituximab.
A recent report presented to the WHO has highlighted significant opportunities for the implementation of 3Rs approaches (i.e. Replacement, Reduction and Refinement of animal tests) within their manuals, guidelines and recommendations for vaccines and biotherapeutics. The report is the culmination of a three-year project led by the UK National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) and co-funded by the Bill & Melinda Gates Foundation. The aim was to review the extent to which animal-based testing methods are currently described in these internationally recognised guidance documents and recommend opportunities for applying the 3Rs. International stakeholders have been engaged throughout the project to gauge opportunities and barriers to adoption of 3Rs approaches and how these vary globally, to inform the recommendations in the report. This paper summarises the output from a series of international stakeholder workshops held between March 2022 and September 2023.
The results of a retrospective analysis of data on rabies virus neutralizing antibody titers of occupationally at-risk individuals receiving vaccination with Abhayrab®, a Vero cell culture-derived inactivated rabies vaccine, are communicated. While rabies vaccines generally elicit strong immunity, specific data on the long-term efficacy of Abhayrab® was previously lacking. The data on neutralizing antibody titers of occupationally immunized individuals receiving a three-dose prophylactic intramuscular regimen (0.5 mL on days 0, 7, and 28) were analyzed retrospectively to evaluate the longevity of humoral response. The data were also used to assess the impact of sex of the individual, their marital status, and age on the humoral response. Our analyses demonstrated that pre-exposure prophylaxis with Abhayrab® elicited protective antibody titers persisting for up to 12 years. The vaccine successfully induced protection in individuals up to 69 years of age. Further, immune responses were not unfavorably influenced by age, sex, or marital status of the individual, and the vaccine maintained a high safety profile. The results of the analyses confirm that a single prophylactic course of Abhayrab® provides broad, long-lived protection. These findings reinforce the clinical importance of preventive vaccination for at-risk populations and support the vaccine's sustained efficacy over a decade post-administration.
Animal (in vivo) potency tests have been utilized for over a century in support of vaccine development and for quality testing. This is a legacy of the best science at the time of their introduction. Advances in knowledge and technology, however, have provided opportunities to utilize more sensitive assays during development and replace legacy animal tests with in vitro alternatives. This coupled with initiatives such as replacement, reduction, and refinement (the 3-R's) and quality by design (QbD) have brought industry and regulators together in the introduction of advanced vaccine control strategies. This article examines historical and current uses of animals in vaccines technical development and control, and their replacement with in vitro alternatives from a risk point of view. An overarching risk is that a vaccine tested with an alternative potency assay fails to protect its target recipient. This can be addressed from the perspective of the assay's association with the vaccine mechanism of action, and the rules used to introduce the vaccine into the patient population (e.g., specifications). Commonly understood concepts such as analytical precision play a role in risk evaluation based on its impact on the sensitivity of a test to detect meaningful product changes caused by variations in manufacture or over a vaccine's shelf life. This should be considered when evaluating solutions such as the reduction of multi-concentration (or dilution) in vivo assays to a single concentration test. While the use of animals in vaccine development will not go away all together, the paradigm must shift from in vivo tests to in vivo models. To help ensure success, principles and practices related to introduction of in vitro alternatives require global collaboration among industry, regulators, pharmacopeias, and supporting organizations.
The National Institute of Food and Drug Safety Evaluation, under the Ministry of Food and Drug Safety in Korea, organized and hosted the 2024 Asian National Control Laboratory (NCL) Network meeting which focussed on regional harmonization of regulatory systems to prepare for cross-border transfer of plasma. The meeting brought together representatives from seven World Health Organization (WHO) member states, along with experts from the WHO, the WHO Regional Office for the Western Pacific, and Thailand Institute of Biological Products, for special lectures. Key topics included considerations for cross-border plasma transfers for fractionation, ensuring the safety of blood and blood products in the Western Pacific region, and the current status of local plasma-derived medicinal products (PDMPs) production in Thailand. Participating countries also shared their latest experiences and updates on national lot release and biological standardization activities. All participants emphasized the need for ongoing coordination among Asian NCLs to address the increasing movement of plasma across borders and the growing demand for PDMPs in Asia. The meeting concluded with agreements to strengthen regulatory capacities and enhance cooperation among Asian NCLs, with WHO playing a central role in supporting these efforts.
The COVID-19 pandemic highlighted significant inequalities in access to medicines and emergency supplies, including vaccines, that persist in Latin America and the Caribbean. From a regional perspective, it is necessary to improve the conditions to ensure more equitable and inclusive access to health technologies, both in normal scenarios and during future biological threats. Technology Transfer emerges as an effective tool to permanently avoid scarcity in global and regional vaccine supplies. Here we describe the global and regional ecosystem of Technology Transfer, its actors, roles, interactions, and evolution through research of publicly available documents and interviews with experts from the region and international institutions. Additionally, we identify and analyze vaccine projects, characterize typologies of projects in the region, suggest an evolution of three temporal phases, reveal lessons from the COVID-19 pandemic and identify four drivers that expedite vaccine Technology Transfer in Latin America and the Caribbean. These drivers include (i) strengthening of regulatory capacities for vaccines; (ii) adoption of trade standards; (iii) increasing manufacture capacity, R&D, and human resources; and (iv) consideration of aggregated demand. Finally, we present recommendations to maximize the potential of scientific-technological and vaccine production capacities in Latin American and the Caribbean. They relate to the four drivers, the promotion of complementary industries, data access and availability policies, inter-institutional dialogue and coordination, public health considerations, and future work in areas of information opacity.
Tuberculin purified protein derivatives (tuberculin PPDs) are heat-treated, protein-enriched products of lysed mycobacteria. Tuberculin PPDs reveal a delayed hypersensitivity in individuals earlier sensitized to mycobacteria and are thereby used to detect tuberculosis. For batch potency testing of tuberculins, the European Pharmacopoeia advises intradermal injection of products into previously sensitized guinea pigs. Batch potency is reflected by the size of the resulting skin lesions as compared to a reference tuberculin. This procedure is quite compromising and results are highly variable, often requiring test repeats. In a proof of concept study, we evaluated the suitability of a combination of liquid chromatography and mass spectrometry (LC-MSE) to record qualitative protein profiles of bovine PPD tuberculin concentrates. Six batches of bovine PPD tuberculin concentrates from three manufacturers and the WHO International Standard for PPD of Mycobacterium bovis tuberculin were studied. In total, 35 proteins were identified by LC-MSE followed by MS database search. Eight proteins were consistently found in all batches of all bovine tuberculin PPD products. Our results suggest that LC-MSE can be used for the analysis of PPD tuberculin concentrates and that it can be further developed in the future into quantitative MS methods for batch analysis, i.e. consistency testing.
The immune system unintentionally targets the synovial lining of the joints in rheumatoid arthritis (RA), a chronic autoimmune disease that causes inflammation, discomfort, and gradual joint destruction. A humanized anti-IL-6R monoclonal antibody (mAb), tocilizumab (TCZ) is primarily used to treat rheumatoid arthritis (RA) as well as a number of other chronic and inflammatory conditions, particularly polyarticular juvenile idiopathic arthritis (pJIA), systemic juvenile idiopathic arthritis (sJIA), and castleman disease. From the identification of interleukin-6 (IL-6) as a crucial inflammatory mediator and its receptor IL-6R to the clinical development of TCZ, this study provides an overview of TCZ. Because of its many therapeutic uses, TCZ has gained widespread use, and several biosimilars have lately entered clinical studies or hit the market. We summarize the upstream production strategies for full-length and fragment mAbs across various eukaryotic and prokaryotic expression systems. Additionally, the review discusses the development, manufacturing, and clinical assessment of TCZ and its biosimilars, including immunogenicity and pharmacokinetic profiles, to ensure their safety and efficacy. Finally, various developmental strategies are outlined for the successful production of biologically functional recombinant TCZ from different host systems.
We report a rapid in vitro method for the potency evaluation of oil-based inactivated Infectious Bronchitis virus (IBV) vaccines. The method is designed to be used by both, quality control laboratories during vaccine manufacturing and by authorizing national laboratories. The simple technique reduces the time and the number of live birds needed for vaccine potency evaluation, effectively promoting a clean environment. Further, the method is a convenient alternative to using the traditional vaccine potency test in which live animals are used. To illustrate a proof of concept, antigens from a total of ten commercial oil adjuvant infectious bronchitis vaccines from different manufacturers were chemically extracted using isopropyl myristate and an antigen capture ELISA test was used to quantify the antigen concentration in the aqueous extracts. The results from the conventional live birds' tests, which determine the antibody titers after 3-4 weeks postvaccination, were compared to their corresponding antigen concentrations obtained by capture ELISA. The results indicate that, vaccines that contain a threshold amount of the specific IBV antigen (here determined to be > 1.26 pg/dose based on an antigen capture ELISA method), can be considered potent without the need to further test in live animals, provided that the concentration of the antigen can be reliably measured in its aqueous phase extract. Moreover, a linear relation between the antigen amount per dose and the antibody titer was found. Overall, the developed methods in this study are suited for high throughput vaccine potency evaluation.
On July 2, 2024, the International Alliance for Biological Standardization (IABS) and Humane Society International (HSI) co-hosted a webinar on the global availability and affordability of critical reagents for vaccine and biologics production. Despite growing support for non-animal testing, significant barriers remain, especially in low-income countries facing financial and supply chain challenges. This meeting showcased successful collaborations on reagent production and shared industry and regulatory perspectives. Key barriers included high reagent costs, import complexities, and the limited number of suppliers. Participants stressed the need for tailored risk-based testing, in-house assay validation, and stronger collaboration for standardised testing. The idea of regional hubs in Africa and Southeast Asia for reagent distribution was also discussed to address logistical challenges. A central theme was advocating reliance strategies, which promote shared regulatory assessments and resource optimisation, as demonstrated by the EU/EEA OCABR Network activities and South African-European laboratory collaborations. Difficulties facing smaller national control laboratories in meeting international standards were highlighted, along with the need for further innovation in non-animal-derived reagents to address these challenges. Participants stressed the importance of continued global collaboration and adopting reliance practices to improve access to critical reagents and ensure sustainability in biologics testing.
A quadrivalent influenza vaccine (QIV) has been available in Japan since the 2015/2016 influenza season. Single radial immunodiffusion (SRID) assays are currently used worldwide to measure the hemagglutinin (HA) content of influenza vaccine components because they are simple, accurate, and the regulatory requirement, ensuring consistency in manufacture for the HA content. However, the cross-reactivity of antisera against the two lineages of the influenza B virus (IFVB) may cause inaccurate quantification of HA content in QIVs using the SRID assay. To examine cross-reactivity and develop an appropriate procedure for accurate measurement of vaccine potency, a collaborative study with four Japanese vaccine manufacturers was conducted to measure the HA contents of trivalent influenza vaccines (TIVs) and QIVs by SRID assay with a single and a mixture of reference antigens (refAgs) from each lineage of IFVB for seven influenza seasons from 2015/16 to 2021/22. The cross-reactivity of the two IFVB components in the SRID assay varied depending on the vaccine viruses. Our study demonstrated that it is useful to validate a suitable combination for each refAg and reference antiserum by selecting the combination showing similar HA contents between experimental TIV and QIV before lot release testing.
Epsilon toxin (Etx) is one of the exotoxins (∼18) secreted by the spore-forming bacterium Clostridium perfringens, which plays a major role in the pathogenesis of enterotoxaemia (ET) leading to sudden death in affected small ruminants. A chemically inactivated toxoid of Etx has been used as a vaccine to control ET in animals. Non-toxic Etx-mutant proteins could potentially be used in the development of efficient immuno-assays and alternative subunit vaccine formulations for the control of ET in animals. In this study, a codon-optimized synthetic quadruple point mutant (Y30A, H106P, H149A, Y196A) of the etx gene of Clostridium perfringens was expressed in Escherichia coli to produce a recombinant protein (331 aa, ∼36 kDa). The rEtx-mutant protein was purified under both non-denaturing and denaturing-renatured conditions using a single-step affinity chromatography and was functionally characterized in vivo and in vitro. A quadruple point mutant of Etx was structurally similar to the wildtype Etx. The rEtx protein was activated by trypsin, and had no toxicity when tested using in vitro and in vivo models. Furthermore, the protein elicited antigen-specific antibodies in mice, rabbit, and guinea pigs. In an indirect ELISA, the rEtx-mutant protein was able to detect specific antibodies in sera from ET-vaccinated sheep.
Next Generation Sequencing (NGS) has proven itself as a suitable replacement technology for traditional viral safety assessment assays in the manufacturing of complex biologics. Most notably, its incorporation into ICH Q5A(R2) in November 2023 endorses the technology platform as a suitable alternative to traditional in vivo, in vitro and PCR-based testing for adventitious viruses based on the risk assessment of the product and its context for use. In addition to the finalization of ICH Q5A(R2), a separate European Pharmacopoeia chapter Ph. Eur. 2.6.41 (High Throughput Sequencing for the Detection of Viral Extraneous Agents) is under review to further outline and provide guidance for the application and validation of NGS-based methodologies. Within the context of avian-based quadrivalent influenza vaccine manufacturing, NGS provides an alternative viral safety assessment method to traditional in vivo based testing models which are requirements for every lot manufactured. However, prior to implementation of NGS alternative methodology for commercial product testing, suitability of the method must be demonstrated within the context of the product through appropriate assay validation. In line with ICHQ5A (R2), 3.2.5.2 Next Generation Sequencing, non-targeted NGS can replace In vivo with broad virus detection for unknown or unexpected virus species without a head-to-head comparison. Therefore, complying with ICH Q5A (R2) and also AstraZeneca internal risk assessment for adventitious agents' detection, a comparability study directly comparing In vivo to NGS was not completed. This article summarizes the collaborative effort between AstraZeneca and MilliporeSigma to replace the in vivo adventitious virus test for Live Attenuated Influenza Vaccine (LAIV) with NGS for broad virus detection as part of a comprehensive virus testing strategy.
Edwin Cohn, appointed to the Harvard Medical School in 1920, was commissioned by the United States military in 1940 to develop a stable albumin solution to treat blood/plasma loss from battlefield injury. Albumin was first produced at the Harvard pilot plant using Cohn's five variable, ethanol precipitation process which was rapidly transferred to private industry for industrial manufacture. For the past decades IgG has been used to treat multiple conditions and has become the industry driver whilst albumin is now a low-price commodity. The development of purification techniques, particularly chromatography, spurred the manufacture of coagulation factors for haemophilia and other proteins from Cohn fractions, leading to the current, unique roster of multiple, essential, plasma-derived medicines. The major cost in fractionation is for plasma, making recombinant and other non-factor alternatives a challenge for the industry. Plasma-derived haemophilia therapies are largely redundant in Western economies, although other products, including prothrombin complex, alpha-1 anti-trypsin, fibrin sealant, provide essential treatments. The established industry is also challenged by potential alternatives to IgG. Despite the plethora of alternative manufacturing technologies, Cohn fractionation in combination with "upstream" harvesting of other proteins through other technologies and "downstream processes" which incorporate unit operations for virus safety is the global industry standard.
There is growing interest of monitoring of glyphosate (GLYP) and its active metabolite, aminomethylphosphonic acid (AMPA) in pharmaceuticals globally. Vaccines represents an important class of pharmaceuticals for human and veterinary use. In this work, a robust, sensitive and direct ultra-high-performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS) based method was developed and validated. This method enables simultaneous detection and quantification of GLYP and AMPA using a simple liquid-liquid extraction technique in complex vaccines. In absence of these residuals, the method was validated using spiked standards of GLYP and AMPA in the selected vaccines. The method demonstrated suitable linearity with r2 > 0.997 over the wide concentration range of 2-50 ng/mL for GLYP and 2-100 ng/mL for AMPA respectively. LOD and LOQ of 0.5 ng/mL and 2 ng/mL for GLYP and AMPA was observed. The method showed precision (RSD of 14 %) and accuracy (83-108 %) in selected vaccines including diphtheria-tetanus-whole cell pertussis-hepatitis B and haemophilus influenzae type B conjugate, diphtheria-tetanus-whole cell pertussis-hepatitis B-haemophilus influenzae type B conjugate and inactivated polio virus, measles-mumps-rubella and pneumococcal polysaccharide conjugate vaccines. The study supports the suitability of the method for simultaneous monitoring of GLYP and AMPA in vaccine formulations.
Immunotoxins (ITs) are chimeric proteins that combine the targeting specificity of a monoclonal antibody or antibody fragment with the cytotoxic properties of a toxin. They offer a promising strategy for cancer therapy by selectively delivering cytotoxic payloads to tumor cells. The epidermal growth factor receptor (EGFR) is frequently overexpressed in various cancers, making it an attractive target for IT-based therapies. In this study, we designed and constructed a novel IT composed of a single-chain variable fragment (scFv) derived from Panitumumab, a humanized monoclonal antibody targeting EGFR, and the Shiga toxin A subunit 2 (Stx2a), a potent cytotoxic agent. The IT was designed using computational tools to optimize the linker region between the scFv and Stx2a domains. The recombinant IT was expressed in a prokaryotic host and purified to homogeneity. The cytotoxic activity of the IT was evaluated in vitro against human colorectal carcinoma (HCT-116) and human embryonic kidney (HEK293) cells. The IT demonstrated significant cytotoxicity against HCT-116 cells, while exhibiting minimal toxicity to non-target cells. To enhance the delivery and efficacy of the IT, we encapsulated it in chitosan nanoparticles. The nanoparticle-based formulation showed improved cellular uptake and enhanced cytotoxicity compared to the free IT. Our findings suggest that the designed IT has the potential to be a promising therapeutic agent against EGFR-expressing cancers. Further studies are warranted to evaluate its efficacy in vivo and to optimize its formulation for clinical applications.
Endotoxin masking poses a potential risk to patient safety by rendering endotoxin undetectable. While research often focuses on international endotoxin standards (RSE), the effects of LPS mutants on Low Endotoxin Recovery (LER) are poorly understood. Our study investigated S. minnesota and E. coli mutants with incomplete O-antigen chains (rough LPS) using Limulus amebocyte lysate (LAL), recombinant Factor C (rFC) and the monocyte activation test (MAT). All tested methods detected the mutants, with variations in activity observed. Measurements over time in a common drug formulation (10 mM sodium citrate and 0.05 % (w/v) polysorbate 20) showed different masking kinetics for the mutants using different methods. We were able to show that LAL and rFC have comparable kinetics, whereas MAT showed improved recovery of masked endotoxin. The study showed that the mutation of LPS have an effect on masking, independent of the assay system. We propose that polysaccharide length affects masking susceptibility, with lower hydrophilic/hydrophobic ratios caused by the shortened polysaccharide chain (rough LPS) reducing masking. In addition, the stronger negative charge of the rough mutants increases cation affinity and is suggested to contribute to the stabilisation of supramolecular structures, making the rough mutants less susceptible to masking than the smooth mutants.
Infectious Bursal Disease is a highly contagious, immunosuppressive viral disease of young chicks caused by the Infectious Bursal Disease Virus (IBDV). The study was carried out at the National Veterinary Institute (NVI) of Ethiopia to evaluate the competence of the DF-1 cell culture adapted vaccine strain of IBDV as a vaccine candidate. DF-1 cells at passage 27 confluent monolayer was infected with 1 ml of LC-75 vaccine strain virus by adsorption method and recorded as passage 1 (P1). This procedure has been repeated up to seven serial passages with the same methods of virus infection onto DF-1 cells. Minor CPEs were observed in the second passage, but vivid cytopathic effects (CPE) were observed starting from passage 3 (P3). The infectivity titer of DF-1 cell adapted virus was determined, and the results showed a linear increase in titer with each passage number. Transcriptase polymerase chain reaction (RT-PCR) targeting the VP2 gene revealed positive 400-base pair amplification. The vaccinated experimental chicks from passages 5 and 7 and the CFC based vaccine showed no clinical signs and/or death. Efficacy test revealed that DF-1 adapted vaccinal strain protected the chicks from the challenged virus strain at passage 5 and 7. The control group, on the other hand, had 100 % morbidity and 91 % mortality. As a result, the DF-1 cell could be used as a model to study IBDV kinetic growth, and the DF-1 cell adapted virus could be a candidate for IBD vaccine development. Thus, IBD vaccine production using DF-1 cells is recommended.