Cell Culture-derived 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.

Awareness on Recent Guidelines for Rabies Prophylaxis among Healthcare Professionals in Rewa District, Madhya Pradesh, India: A Questionnaire-based Cross-sectional Study

Introduction: Rabies is a zoonotic disease that can be fatal and continues to impose a significant financial burden on developing countries. Recently, there have been advancements in the introduction of cell culture vaccines and immunoglobulin, as well as the approval of Intradermal (ID) schedules for vaccine administration. Aim: To assess the knowledge of doctors in Rewa District regarding the National Guidelines for Rabies Prophylaxis in 2019. Materials and Methods: A cross-sectional study was conducted, involving doctors from tertiary healthcare centres, district hospitals, and private practices. Data were collected over a period of one month from 206 doctors using a Google form, which included information about their field of practice and their knowledge of recent guidelines on Rabies prophylaxis. Data analysis was performed using the Chi-square test. Results: Out of the 206 doctors surveyed, 92 (44.7%) were male. A 56.7% of the doctors were aware of the regimen and dosage for ID administration of the Anti Rabies Vaccine, (ARV) and 44.6% were knowledgeable about the modification of PostExposure Prophylaxis (PEP) to Pre-Exposure Prophylaxis (PrEP) in the Essen regimen. Furthermore, 70.9% of the doctors were familiar with the dosage of Human Rabies Immunoglobulin (HRIG), while 42.7% knew how to manage animal bites in immunocompromised patients. Conclusion: The study revealed a lack of sufficient knowledge on various aspects of rabies management among the doctors surveyed. This underscores the need for reorientation programs and Continuing Medical Education (CMEs) training to be provided to doctors to enhance their knowledge of rabies and improve the effective management of animal bites.

Health professionals KAP study on rabies exposure assessment and NTV administration in Ethiopia

Background: Globally, it’s estimated 60,000 human deaths occur due to rabies with 95% of cases occurring in Africa and Asia. Annually, thousands of people are infected with rabies in Ethiopia and more than 2700 people die. In Ethiopia, the neural-based vaccine has been used since the 1950’s. Due to the old method of production, low immunogenicity and vaccine associated adverse events, WHO discourage the use of this vaccine and recommend replacing it with a safe and effective modern cell culture vaccine. There was no specific guidelines and training for this vaccine and health professional mismanage the nerve tissue vaccine (NTV) with cell culture vaccine resulting in vaccination failure. This study identifies professional knowledge, attitude and practice (KAP), vaccine related adverse events and the burden of rabies cases in humans. Methods: Data were collected from health professionals in selected health facilities using structured questionnaire to identify the level of KAP. Results: The study identified overall gaps in the professionals KAP as below standard which is not more than 25%. The majority of the respondents (97%) reported vaccine associated local adverse events followed by 20% systemic complications during vaccination. Only 2.4% of the respondents reported post-vaccine complications. Rabies cases in humans at those covered health facilities were reported to be 32 during the one-year study period with an average of two cases at each facility. Conclusions: Gaps identified in the professional KAP result indicate the need to provide specific training based on standard guidelines. Generally, the study indicates the need to strengthen rabies prevention and control efforts through inter-sectoral collaboration, and facilitating the establishment of facility-based rabies palliative care centers. In addition, it is recommended to work on technology transfer to replace old method of NTV production with safe and effective modern cell culture based anti-rabies vaccine production for effective rabies PEP.

Developments in Rabies Vaccines: The Path Traversed from Pasteur to the Modern Era of Immunization.

Rabies is a disease of antiquity and has a history spanning millennia ever since the first interactions between humans and dogs. The alarming fatalities caused by this disease have triggered rabies prevention strategies since the first century BC. There have been numerous attempts over the past 100 years to develop rabies vaccineswith the goal of preventing rabies in both humans and animals. Thepre-Pasteurian vaccinologists, paved the way for the actual history of rabies vaccines with the development of first generation vaccines. Further improvements for less reactive and more immunogenic vaccines have led to the expansion of embryo vaccines, tissue culture vaccines, cell culture vaccines, modified live vaccines, inactivated vaccines, and adjuvanted vaccines. The adventof recombinant technology and reverse genetics have given insight into the rabies viral genome and facilitated genome manipulations, which in turn led to the emergence of next-generation rabies vaccines, such as recombinant vaccines, viral vector vaccines, genetically modified vaccines, and nucleic acid vaccines. These vaccines were very helpful in overcoming the drawbacks of conventional rabies vaccines with increased immunogenicity and clinical efficacies. The path traversed in the development of rabies vaccines from Pasteur to the modern era vaccines, though, faced numerous challenges;these pioneering works have formed the cornerstone for the generation of thecurrent successful vaccines to prevent rabies. In the future, advancements in the scientific technologies and research focus will definitely lay the path for much more sophisticated vaccine candidates for rabies elimination.

Immunogenicity studies of nucleic acid-based antirabies vaccines in BALB/c mice

Improved vaccine efficacy has a major impact on future rabies prevention and control. In this systematic review, a comparative assessment of different nucleic acid-based antirabies vaccination tools developed using different methods, in different countries, was undertaken. The comprehensive search was done in three databases. Articles were carefully selected based on predetermined inclusion/exclusion criteria and eight articles were included in this systematic review. Studies have demonstrated dose-dependent immune response following intramuscular vaccination and improved immune response following intranasal vaccination and gene-gun delivery method. Nucleic acid-based antirabies vaccines have shown higher immune response and protective levels in Bagg's albino (BALB/c) mouse models than cell culture-derived vaccines. It has been demonstrated that the route/method of administration and the vaccine formulation could be improved in various ways to enhance immune response following vaccination. These new vaccine tools and their implementation in pre- and postexposure prophylaxis could be further evaluated and to be adopted by rabies endemic countries.

Effect of Repeat Vaccination on Immunogenicity of Quadrivalent Cell-Culture and Recombinant Influenza Vaccines Among Healthcare Personnel Aged 18-64 Years: A Randomized, Open-Label Trial.

Antibody responses to non-egg-based standard-dose cell-culture influenza vaccine (containing 15 µg hemagglutinin [HA]/component) and recombinant vaccine (containing 45 µg HA/component) during consecutive seasons have not been studied in the United States. In a randomized trial of immunogenicity of quadrivalent influenza vaccines among healthcare personnel (HCP) aged 18-64 years over 2 consecutive seasons, HCP who received recombinant-HA influenza vaccine (RIV) or cell culture-based inactivated influenza vaccine (ccIIV) during the first season (year 1) were re-randomized the second season of 2019-2020 (year 2 [Y2]) to receive ccIIV or RIV, resulting in 4 ccIIV/RIV combinations. In Y2, hemagglutination inhibition antibody titers against reference cell-grown vaccine viruses were compared in each ccIIV/RIV group with titers among HCP randomized both seasons to receive egg-based, standard-dose inactivated influenza vaccine (IIV) using geometric mean titer (GMT) ratios of Y2 post-vaccination titers. Y2 data from 414 HCP were analyzed per protocol. Compared with 60 IIV/IIV recipients, 74 RIV/RIV and 106 ccIIV/RIV recipients showed significantly elevated GMT ratios (Bonferroni corrected P < .007) against all components except A(H3N2). Post-vaccination GMT ratios for ccIIV/ccIIV and RIV/ccIIV were not significantly elevated compared with IIV/IIV except for RIV/ccIIV against A(H1N1)pdm09. In adult HCP, receipt of RIV in 2 consecutive seasons or the second season was more immunogenic than consecutive egg-based IIV for 3 of the 4 components of quadrivalent vaccine. Immunogenicity of ccIIV/ccIIV was similar to that of IIV/IIV. Differences in HA antigen content may play a role in immunogenicity of influenza vaccination in consecutive seasons. NCT03722589.

Development and validation of an in vitro titrimetric method for determination of classical swine fever viruses in PK-15 cells

Classical swine fever (CSF) is a highly contagious notifiable disease of pigs caused by CSF virus of Flaviviridae family. Previously, lapinized vaccines were used for the disease control, which has now been replaced with cell culture vaccines. Determination of virus titre is the key factor for development and quality control testing of classical swine fever (CSF) cell culture vaccines. Since CSFV is a non- cytopathic virus, an accurate method for the titration of this virus in cell culture has not yet been reported. Here we present a full proof method of titration of CSF cell culture viruses employing Fluorescent Antibody Technique (FAT) in 24 well plate cover slip culture of PK-15 cells. CSFV monoclonal antibodies (Mab) used in the test bind to the CSF virus particles in the cell cytoplasm of the infected cells and the immune-fluorescence signal is produced by subsequent binding of FITC conjugate with Mab. In this newly developed method, apple green fluorescence is observed in the cytoplasm of the infected cells as the virus multiplies only in the cytoplasm. The nucleus as well as the uninfected cells cytoplasm is stained red without any traces of green fluorescence. Thus, the test clearly differentiates a CSFV infected cell from the uninfected cells in the vicinity, if any, and also from the uninfected controls. The test can also quantify the accurate titres of CSF live viruses in the cell culture vaccines and hence it has wide application in routine virus titration applied for manufacturing of CSF cell culture vaccines, determination of accurate multiplicity of infection (m.o.i.) during infection and quality control of vaccines by the testing laboratories.

Influenza vaccines: where we are, where we are going.

Influenza vaccines are the most useful strategy for preventing influenza illness, especially in the setting of the COVID-19 pandemic. For the coming year (2021/2022) all vaccines will be quadrivalent and contain two influenza A strains [(H1N1)pdm09-like and (H3N2)-like viruses] and two influenza B strains (Victoria lineage-like and Yamagata lineage-like viruses). However, the currently licensed have suboptimal efficacy due to the emergence of new strains and vaccine production limitations. In this review, we summarize the current recommendations as well as new advancements in influenza vaccinations. Recent advances have been aimed at moving away from egg-based vaccines and toward cell culture and recombinant vaccines. This removes egg adaptations that decrease vaccine efficacy, removes the reliance on egg availability and decreases the time necessary to manufacture vaccines. However, even more radical changes are needed if we are to reach the ultimate goal of a universal vaccine capable of providing long-lasting protection against all or at least most influenza strains. We discuss various strategies, including using more stable influenza antigens such as the hemagglutinin stalk and internal proteins as well as new adjuvants, new vaccine formulations, and DNA/RNA-based vaccines that are currently being developed. The currently available vaccines have suboptimal efficacy and do not provide adequate protection against drifted and shifted strains. Thus, the development of a universal influenza vaccine that induces long-lasing immunity and protects against a broad range of strains is crucial.

Relative Effectiveness of Cell-Cultured versus Egg-Based Seasonal Influenza Vaccines in Preventing Influenza-Related Outcomes in Subjects 18 Years Old or Older: A Systematic Review and Meta-Analysis

Avian mutations in vaccine strains obtained from embryonated eggs could impair vaccine effectiveness. We performed a systematic review and meta-analysis of the adjusted relative vaccine effectiveness (arVE) of seed cell-cultured influenza vaccines (ccIV) compared to egg-based influenza vaccines (eIV) in preventing laboratory-confirmed influenza related outcomes (IRO) or IRO by clinical codes, in subjects 18 and over. We completed the literature search in January 2021; applied exclusion criteria, evaluated risk of bias of the evidence, and performed heterogeneity, publication bias, qualitative, quantitative and sensitivity analyses. All estimates were computed using a random approach. International Prospective Register of Systematic Reviews, CRD42021228290. We identified 12 publications that reported 26 adjusted arVE results. Five publications reported 13 laboratory confirmed arVE and seven reported 13 code-ascertained arVE. Nine publications with 22 results were at low risk of bias. Heterogeneity was explained by season. We found a significant 11% (8 to 14%) adjusted arVE favoring ccIV in preventing any IRO in the 2017–2018 influenza season. The arVE was 3% (−2% to 7%) in the 2018–2019 influenza season. We found moderate evidence of a significant advantage of the ccIV in preventing IRO, compared to eIV, in a well-matched A(H3N2) predominant season.

Acute motor axonal neuropathy following anti-rabies human diploid cell vaccine: A rare case and review

Rationale: Guillain Barre syndrome (GBS) is an acute neurological illness leading to quadriparesis with respiratory involvement. It can be triggered by infections, vaccinations, surgery, trauma, transplantation and drugs. Anti-rabies cell culture vaccines introduced to overcome the high rate of neurological complications associated with tissue based rabies vaccine, can be very rarely associated with GBS.Patient concerns: A 50-year-old female presented with acute severe upper back pain evolving into pure motor quadriparesis following administration of human diploid cell vaccine for rabies.Diagnosis: Acute motor axonal neuropathy variant of GBS following anti-rabies human diploid cell vaccine.Interventions: Intravenous high dose steroids.Outcomes: Patient recovered completely within 1 month.Lessons: Although anti-rabies cell culture vaccines are highly immunogenic and safe, they are rarely associated with GBS. Clinicians should be aware of this link because prompt diagnosis and treatment can result in complete recovery and avoid complications.

A randomized controlled trial of antibody response to 2019–20 cell-based inactivated and egg-based live attenuated influenza vaccines in children and young adults

BackgroundHemagglutination inhibition (HAI) titers to the live-attenuated influenza vaccine (LAIV4) are typically lower than its counterpart egg-based inactivated influenza vaccines (IIV). Similar comparisons have not been made between LAIV4 and the 4-strain, cell-culture inactivated influenza vaccine (ccIIV4). We compared healthy children’s and young adults’ HAI titers against the 2019–2020 LAIV4 and ccIIV4. MethodsParticipants aged 4–21 years were randomized 1:1 to receive ccIIV4 (n = 100) or LAIV4 (n = 98). Blood was drawn prevaccination and on day 28 (21–35) post vaccination. HAI assays against egg-grown A/H1N1, A/H3N2, both vaccine B strains and cell-grown A/H3N2 antigens were conducted. Primary outcomes were geometric mean titers (GMT) and geometric mean fold rise (GMFR) in titers. ResultsGMTs to A/H1N1, A/H3N2 and B/Victoria increased following both ccIIV and LAIV and to B/Yamagata following ccIIV (p < 0.05). The GMFR range was 2.4–3.0 times higher for ccIIV4 than for LAIV4 (p < 0.001). Within vaccine types, egg-grown A/H3N2 GMTs were higher (p < 0.05) than cell-grown GMTs [ccIIV4 day 28: egg = 205 (95% CI: 178–237); cell = 136 (95% CI:113–165); LAIV4 day 28: egg = 96 (95% CI: 83–112); cell = 63 (95% CI: 58–74)]. The GMFR to A/H3N2 cell-grown and egg-grown antigens were similar. Pre-vaccination titers inversely predicted GMFR. ConclusionThe HAI response to ccIIV4 was greater than LAIV4 in this study of mostly older children, and day 0 HAI titers inversely predicted GMFR for both vaccines. Lower prevaccination titers were associated with greater GMFR in both vaccine groups.

99. Immune Responses to Influenza Vaccines in Children and Young Adults

BackgroundImmune responses to influenza vaccines (IV) are influenced by pre-existing antibodies to vaccine components. Immune responses to vaccines were evaluated following vaccination with quadrivalent egg-based live-attenuated influenza vaccine (LAIV4) and cell-culture inactivated influenza vaccine (ccIIV4).MethodsRacially diverse (48.0% non-white), healthy, community-dwelling children and young adults aged 4-21 years (median, 18.3 years) were randomized 1:1 in blocks of 4 to receive intramuscular ccIIV4 (Flucelvax: n=100) or nasal LAIV4 (FluMist: n=98); baseline demographics were similar between groups. Blood was drawn at day 0 pre-vaccination and at day 28 (21-35 days) post vaccination. Hemagglutination inhibition (HI) assays against egg-grown A/H1N1, A/H3N2, both vaccine B/strains and cell-grown A/H3N2 antigens were conducted. Geometric mean titers (GMT) and geometric mean fold rise (GMFR) in titers were analyzed. ResultsDay 0 GMTs were similar for LAIV4 and ccIIV4. Day 28 GMTs were higher for ccIIV4 (p< 0.05) and increased following vaccination for all 5 antigens (p< 0.05) except B/Phuket following LAIV4. The GMFR range was 2.4 to 3.0 for ccIIV4 and 1.0 to 1.3 for LAIV4. In linear regression controlling for age and prior season vaccination for both vaccines, baseline titers inversely predicted GMFR. The GMFR to A/H3N2 cell-grown and egg-grown antigens were similar within vaccine type.Figure 1. Day 0 and Day 28 A(H1N1) titers for ccIIV4Figure 2. Day 0 and Day 28 A(H1N1) titers for LAIV4ConclusionThe HI response to ccIIV4 was greater than LAIV4 in this study of mostly older children. Day 0 HI titers were 1) a significant determinant of GMFR; 2) the strongest predictors of day 28 GMFR; and 3) more highly correlated (negatively) with GMFR following ccIIV4 than LAIV4. For both IV, the GMFR for cell-grown and egg-grown A/H3N2 antigens did not differ within IV type. Future studies incorporating immunoglobulin and cellular immune responses may delineate differences between these IV types not observable through HI assays. Disclosures Mary Patricia Nowalk, PhD, Merck & Co., Inc. (Grant/Research Support) Richard K. Zimmerman, MA;MD;MPH;MS, Sanofi Pasteur (Research Grant or Support) Judith M. Martin, MD, Merck Sharp and Dohme (Consultant)

Cell Culture-Derived Tilapia Lake Virus-Inactivated Vaccine Containing Montanide Adjuvant Provides High Protection against Viral Challenge for Tilapia.

Tilapia lake virus (TiLV) is a newly emerging pathogen responsible for high mortality and economic losses in the global tilapia industry. Currently, no antiviral therapy or vaccines are available for the control of this disease. The goal of the present study was to evaluate the immunological effects and protective efficacy of formaldehyde- and β-propiolactone-inactivated vaccines against TiLV in the presence and absence of the Montanide IMS 1312 VG adjuvant in tilapia. We found that β-propiolactone inactivation of viral particles generated a vaccine with a higher protection efficacy against virus challenge than did formaldehyde. The relative percent survivals of vaccinated fish at doses of 108, 107, and 106 50% tissue culture infectious dose (TCID50)/mL were 42.9%, 28.5%, and 14.3% in the absence of the adjuvant and 85.7%, 64.3%, and 32.1% in its presence, respectively. The vaccine generated specific IgM and neutralizing antibodies against TiLV at 3 weeks following immunization that were significantly increased after a second booster immunization. The steady state mRNA levels of the genes tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interferon γ (IFN-γ), cluster of differentiation 4 (CD4), major histocompatibility complex (MHC)-Ia, and MHC-II were all increased and indicated successful immune stimulation against TiLV. The vaccine also significantly lowered the viral loads and resulted in significant increases in survival, indicating that the vaccine may also inhibit viral proliferation as well as stimulate a protective antibody response. The β-propiolactone-inactivated TiLV vaccine coupled with the adjuvant Montanide IMS 1312 VG and booster immunizations can provide a high level of protection from virus challenge in tilapia.

Safety and immunogenicity of SURE RAB™, an inactivated cell culture derived rabies vaccine: A comparative, phase III clinical trial

IntroductionRabies is a viral zoonotic disease widespread across the world. In India, various cell culture vaccines are available for pre and post exposure prophylaxis (PEP) but are not sufficient to meet the rising demand. The present study evaluated the safety and immunogenicity of Rabies vaccine Human I.P. (Brand name: SURE RAB™) in PEP and demonstrated its non-inferiority to already approved rabies vaccine (Brand name: VERORAB). Material and methodsIt was a phase-III randomized, open label, comparative, single centre clinical trial in post exposure subjects. Safety and immunogenicity were evaluated at Day 0, 14 and 45 ± 7 post vaccination. Day 14 serum samples were analyzed by Enzyme Linked Immunesorbent assay (IgG ELISA, Bio-Rad) and Day 0, 14 and 45 ± 7 serum were tested by Rapid Fluorescent Focus Inhibition Test (RFFIT). Paired t-test was applied to compare the results of Rabies virus neutralizing antibody (RVNA). The severity of adverse reactions was measured on a scale of excellent, good, fair and bad; p-value (p < 0.05) was considered as statistically significant. ResultsAll the subjects achieved a protective titer value between 0.5 and 9.0 IU/ml by Day 14 tested by ELISA and significant rise in the antibody titer in all the groups when tested after 45 days. Statistically significant p-value (p < 0.001) observed with RFFIT test indicated biological potency of rabies vaccine. Adverse events and safety was comparable statistically between three groups (p ​= ​0.886) and Group I ​+ ​II combined versus Group III (p = 0.495). ConclusionThe study results conclusively demonstrate that SURE RAB™ is comparable to VERORAB in terms of safety and immunogenicity and can be used for PEP in rabies.

An unusual case of fatal rabies encephalitis despite completing postexposure prophylaxis

Rabies continues to be a major health scourge in many developing countries including India. It can be effectively prevented by providing postexposure prophylactic treatment. Failure of Rabies postexposure prophylaxis (PEP) is a rare occurrence. Our patient, a 39-year-old Male, was bitten by stray dog on the left hand. It was Category III dog bite for which proper wound care and PEP 5 doses of antirabies cell culture vaccine and Human Rabies Immunoglobulin was given. Two days after completing the 5th dose of PEP, he presented with fever, neck rigidity, drooling of saliva, pain, and numbness in the left hand along with auditory and visual hallucinations without hydrophobia and aerophobia. On 2nd say of hospitalization, he developed progressive respiratory difficulty and decreased oxygen saturation for which he was intubated and put on invasive ventilator support. However, he suffered fatal cardiac arrest and succumbed to his illness. Based on his symptoms, a clinical diagnosis of febrile encephalopathy with differential diagnosis of acute rabies encephalitis was made. On autopsy, his brain was markedly congested and histopathological examination was suggestive of acute rabies encephalitis. However, no Negri bodies were seen. Further examination of brain tissue by immunohistochemical labeling revealed numerous Negri bodies and confirmed the diagnosis of rabies encephalitis.

Molecular Characterization and Pathogenicity of an Indian Isolate of Duck Enteritis Virus Recovered From a Natural Outbreak

Background: Duck plague is a highly contagious viral disease reported in our country very often with significant economic loss. There are some bottlenecks with the currently used ‘Holland strain’ vaccine that involves cumbersome process of vaccine production in embryonated chicken eggs. With the future goal of development of an indigenous cell culture vaccine for duck plague, the present study is aimed at isolation of an Indian strain of DEV from a natural outbreak and its characterization for the seed virus purpose. Methods: Liver samples were collected from the suspected ducks died during a natural outbreak in Kerala and subjected to polymerase chain reaction (PCR) to confirm presence of viral DNA. The duck enteritis virus (DEV) was isolated by inoculation of PCR positive samples in embryonated duck eggs/ducklings and its pathogenicity was studied. Further, the DEV recovered from the infected duck embryo and duckling liver was confirmed by PCR amplification of the viral DNA polymerase gene and its sequence analysis. Result: Out of 12 liver samples tested eight (8) were found to be positive for duck plague by PCR. The DEV infected duck embryos and ducklings died showing typical signs and characteristic gross and microscopic lesions. PCR amplification of viral DNA targeting the DNA polymerase gene yielded amplicon of expected size of 446bp. The amplicon sequence showed 99-100% homology with other DEV isolates, thus confirming the new isolate as DEV, named as DEV/India/IVRI-2016 and the gene sequence has NCBI acc. no. KX511893.

Stability of live attenuated classical swine fever cell culture vaccine virus in liquid form for developing an oral vaccine

Classical swine fever (CSF) is an important viral disease of pigs and controlled by vaccination. Unorganised backyard and wild pigs are difficult to vaccinate by needle vaccination. Here we formulated liquid vaccines using an Indian CSF cell culture vaccine virus and four stabilisers and evaluated their stability at 4 °C, 25 °C and 37 °C up to 24 h for use as oral vaccine. The stabilisers were Lactalbumin hydrolysate-Trehalose, Lactalbumin hydrolysate-Trehalose-Gelatin, Lactalbumin hydrolysate-Lactose-Sucrose and Lactalbumin hydrolysate-Sucrose. The liquid vaccines, with or without stabilisers, were stable at 4 °C up to 24 h, whereas, a drop of one log10 titre was observed at 25 °C during the same period. At 37 °C, the virus titre diminished by only one log10 with the Lactalbumin hydrolysate-Trehalose (LT) stabiliser up to 24 h compared to two log10 losses in virus titre with other stabilisers and virus control. We therefore conclude that for developing a CSF oral vaccine, the vaccine virus in liquid form can be used directly during the winter, whereas for developing the oral vaccine for summer, the LT stabiliser would provide maximum stability to the virus to withstand the warm temperature while maintaining adequate therapeutic titre for inducing a protective immune response.

Immunogenicity and safety of purified vero cell-cultured rabies vaccine under Zagreb 2-1-1 or 5-dose Essen regimen in the healthy Chinese subjects: a randomized, double-blind, positive controlled phase 3 clinical trial

ABSTRACT Aim: The aims of the study were to evaluate the non-inferiority of the safety and immunogenicity of a new trial purified vero cell-cultured rabies vaccine (trial vaccine) in healthy subjects comparing with the control purified vero cell-cultured rabies vaccine (control vaccine) following Essen regimen and to evaluate the non-inferiority of the safety and immunogenicity of the trial vaccine following two intramuscular regimens, between Zagreb and Essen regimen. Methods: Serum samples were collected before vaccination and on d 7, 14, 35/42 post vaccination. Adverse events (AEs) were recorded for 30 d following each vaccination. This study was registered in the Chinese Clinical Trial Registry (ChiCTR-PPR-15007057). Results: There was no significant difference in the incidence of AEs, local and systemic reactions, among Zagreb group, Essen group, and control group. But the incidence of solicited AEs was a significant difference among the three groups (p = 0.0498). The incidence of solicited AEs was higher in Essen group than that in control group and Zagreb group (p = 0.0278, p = 0.0248). In the subjects whose antibodies were seronegative before vaccination, the seroconversion rates of antibodies among three groups were all 100.0% on d 14 and d 35/42. The Essen group was not inferior to the control group, and the Zagreb group was not inferior to the Essen group on d 14. On d 14 and d 35/42, the geometric mean concentration of the three groups was much higher than the immune protection level of 0.5 IU/ml. Conclusions: The trial vaccine had good safety and immunogenicity, and the trial vaccine is not inferior to the control vaccine. Abbreviations: PVRV: purified vero cell-cultured rabies vaccine; AE: adverse event; CI: confidence interval; GMC: geometric mean concentration; IM: intramuscular; NIFDC: National Institutes for Food and Drug Control; PPS: per-protocol set; SS: safety set; REFIT: Rapid Fluorescent Focus Inhibition Test; RVNA: rabies virus neutralizing antibody; WHO: World Health Organization.

Immunogenicity and protective efficacy of an EB66® cell culture-derived duck Tembusu virus vaccine

ABSTRACT The avian EB66® cell line, derived from duck embryonic stem cells, has been widely used for producing human and animal therapeutic proteins and vaccines. In current study we evaluated the potential use of EB66® cell line in a cell culture-derived duck Tembusu virus (DTMUV) vaccine development. After optimizing the growth conditions of DTMUV HB strain in EB66® cells, we successfully generated three batches of viruses with ELD50 titres of 105.9/0.1 ml, 105.3/0.1 ml and 105.5/0.1 ml, respectively, for using in the preparation of inactivated vaccines. The immunogenicity and protective efficacy of these EB66® cells-derived inactivated vaccines were examined in ducks. Results indicated that all three batches of vaccines induced haemagglutination-inhibition (HI) antibody response in immunized birds at 2 weeks after a single immunization. Immunized ducks and ducklings were protected against a virulent challenge at 4 weeks after a booster immunization. The duration of immunity was for 3–4 months after a booster immunization. These results demonstrated the feasibility of using EB66® cell line to grow up DTMUV for vaccine preparation. RESEARCH HIGHLIGHTS Duck Tembusu virus can be propagated in EB66® cells. EB66® cell-derived inactivated DTMUV vaccines are immunogenic and can provide protection against a virulent challenge. A long-lasting immunity is induced after a booster immunization.

Signals and trends of Guillain–Barré syndrome after the introduction of live-attenuated vaccines for influenza in the US and South Korean adverse event reporting systems

BackgroundWith the advent of live-attenuated, quadrivalent, and cell-cultured vaccines for influenza, there have been discussions on the safety of these vaccines compared to conventional vaccines (such as inactivated, trivalent, and egg-cultured vaccines) because of the development of neurological adverse events (AEs). This study aimed to compare the trends and safety signals in the AE reporting systems of the US and South Korea and, more particularly, to evaluate the association between influenza vaccination and Guillain–Barré syndrome (GBS). MethodsIn total, 400,535 AE reports from the US Vaccine Adverse Event Reporting System (VAERS) and 28,766 AE reports from the Korea Adverse Event Reporting System (KAERS) between 2005 and 2017 were assessed. Disproportionality analysis was performed to detect the safety signals and examine the potential risk of GBS with influenza vaccination using the case/non-case approach. ResultsIn both databases, GBS was the most frequently reported AE following influenza immunization. Using the case/non-case approach, the adjusted reporting odds ratio (ROR) of GBS was 3.57 (95% confidence interval [CI], 3.16–4.03) and 3.09 (95% CI, 0.83–11.45) in the VAERS and KAERS data, respectively. People vaccinated with live-attenuated vaccines reported 2.30 times (95% CI, 1.74–3.05) more cases of GBS than those vaccinated with other types of vaccines. ConclusionsOur analysis of the VAERS and KAERS reports for AEs following immunization (AEFI) for influenza shows the need for cautious monitoring regarding the development of GBS after influenza vaccination, particularly, after live-attenuated vaccination. However, owing to potential reporting bias caused by limited AEFI reports after the introduction of new types of influenza vaccines, further prospective safety studies are needed.