Inactivated Vaccine Research Articles (Page 1)

Triple-TLR agonists' adjuvanted inactivated Newcastle disease virus vaccine promotes effective Th1/Th2 immune responses and affords protective efficacy in chickens.

To address suboptimal antibody induction by commercial PEDV vaccines, we constructed a recombinant adeno-associated virus (rAAV-CMV-PEDV S1) expressing regions of the PEDV S1 subunit based on Adeno-associated virus serotype 2 (AAV-2) vector. In mice, rAAV-CMV-PEDV S1 induced significantly more remarkable and persistent serum-specific IgG compared with the inactivated vaccine and accompanied by robust CD3+CD8+ T cells activation within 4 weeks post-immunization. In pregnant sows, compared with commercially available inactivated and attenuated vaccines, the rAAV-CMV-PEDV S1 induced significantly higher serum and colostral IgG as well as neutralizing antibody titers, which provided piglets with abundant maternal antibodies. Crucially, challenge experiments demonstrated that rAAV-CMV-PEDV S1 conferred 80% clinical protective efficacy for piglets, accompanied by significantly reduced viral shedding loads, surpassing other vaccine groups. These findings suggest that rAAV-CMV-PEDV S1 candidate could be a promising PEDV vaccine for enhancing antibody levels and could strengthen the protection of piglets against PEDV infection.

Throughout human history, contagious infectious diseases have significantly impacted societies, shaping the fate of great dynasties and challenging economic and political systems, social relations, and the overall well-being of the human species. The SARS-CoV-2 pandemic brought unprecedented challenges, emerging in the context of extreme globalization and rapid technological development. The speed of viral spread, the highest absolute mortality rate caused by a viral agent in the last 100 years, and the severe economic and social consequences imposed an urgent need for vaccine development on a previously unimaginable timescale. The proven safety and efficacy of inactivated vaccines enabled the development and large-scale application of the first immunizer against SARS-CoV-2 in less than a year after the World Health Organization (WHO) declared the pandemic. In this review, we discuss the importance of inactivated antiviral vaccines and their historical impact in containing highly harmful diseases affecting humanity. We also explore the cellular mechanisms by which inactivated vaccines may induce immunogenic responses against viral pathogens. In addition, we bring to light a discussion about a fast, cost-effective, potentially efficient technology for large-scale immunizer production: High hydrostatic pressure (HHP), a method long supported by decades of preclinical studies and which is especially effective in the context of enveloped viruses. Finally, we discuss the role of inactivated antiviral vaccines in the face of advances in biotechnology and, therefore, the emergence of vaccines that use genetic engineering in their production, such as RNA, DNA and viral vaccines, which have gained special prominence during the COVID-19 pandemic.

Background: Foot-and-Mouth Disease (FMD) remains a persistent global threat to livestock health and food security, particularly in endemic and resource-constrained regions. Conventional inactivated vaccines pose several challenges—including biosafety risks and dependence on cold-chain logistics. These limitations have prompted growing interest in plant-based recombinant vaccine platforms as innovative, scalable, and safer alternatives for FMD prevention. Methods: This study employed a qualitative meta-synthesis approach, guided by the Barroso–Sandelowski method, to systematically extract, interpret, and integrate findings from 35 peer-reviewed empirical studies published between 2000 and 2025. The selected studies focused on the development and evaluation of plant-made vaccines targeting FMD. Thematic coding and interpretive synthesis were applied to identify recurrent patterns, challenges, and opportunities across the literature. Results: The analysis yielded four dominant themes: (1) Platform Diversity: A variety of plant and algal expression hosts were used through transient or stable transformation systems, (2) Immunization Routes: Oral vaccination was noted for its logistical advantages and potential for mass immunization, though often requiring adjuvants to enhance immunogenicity, (3) Scale-Up Challenges: Key barriers included low recombinant protein yields, heterogeneity in post-translational modifications and high variability between production batches and (4) Regulatory Readiness: Despite encouraging preclinical data, most candidates have not progressed beyond experimental stages. Conclusion: Plant-based recombinant vaccines represent a promising frontier in the fight against FMD, offering novel avenues for safer, more accessible immunization strategies. However, their transition from bench to field remains hindered by technical limitations in expression and purification, as well as institutional and regulatory gaps.

Comparative investigation into the immune efficiency of the single intradermal and intramuscular delivery of foot-and-mouth disease inactivated vaccine in swine.

This study aimed to characterize Mycoplasmosis bovis strain 16M—a highly virulent isolate from one Chinese outbreak—as a candidate for challenge models and inactivated vaccine development. We assessed strain 16M through morphological observation, PCR identification, drug susceptibility testing, growth titer and biofilm quantification, immunological profiling, and calf challenge experiments. We used genomic resequencing to evaluate the genetic stability across 150 passages. Classified as the prevalent ST52 lineage in China, strain 16M showed phylogenetic proximity to strain 08M and exhibited multidrug resistance (notably to macrolides). It achieved higher titers and stronger biofilm formation than other isolates and the reference strain PG45. In calves, intratracheal inoculation with 16M induced universal infection, severe pulmonary consolidation, and peribronchial cuffing, with significantly higher disease scores (p < 0.01). The inactivated 16M vaccine elicited elevated antigen-specific IgG titers, PBMC proliferation, and IFN-γ production versus PG45. Post challenge, immunized calves showed reduced pathological lesions, shorter bacterial shedding, and lower disease scores than the infected controls (p < 0.05). Genetic stability was confirmed for virulence-associated genes (e.g., adhesion proteins), with stable titers and biofilm production within 50 generations. Strain 16M combines high virulence for challenge modeling and industrial-scale vaccine suitability, owing to its robust growth, stable immunogenicity, and genetic consistency.

Genotype-matched recombiant inactivated Newcastle disease virus vaccine confer protection against genotype Ⅻ challenge in geese with maternal antibodies.

Effects of high-dose versus standard-dose influenza vaccine among patients with chronic lung disease: A prespecified analysis of the DANFLU-1 trial.

Immunogenicity and safety of co-administration of sabin-strain-based inactivated poliovirus vaccine, diphtheria-tetanus-acellular pertussis vaccine, and live attenuated hepatitis A vaccine in 18-month-old children: A multicenter randomized controlled non-inferiority trial in China.

Enhanced protection through genotype-matched bivalent H9N2-Newcastle disease virus vaccination: Comparative efficacy against contemporary field strains in specific-pathogen-free chickens.

High-yield production and preclinical protection assessment of a Chinese Hamster Ovary-K1 (CHO-K1) derived PRV gB and gD subunit vaccine against variant pseudorabies virus in pigs.

Avian influenza H9N2 virus has established itself as endemic in various parts of the globe notably in the Middle East with significant economic repercussions. Vaccination with inactivated vaccine is regarded as one of the most effective strategies for disease prevention. To enhance the efficacy of the vaccination protocol the seed strain must possess genetic and antigenic characteristics closely resemble to the circulating field viruses. This research sought to assess the effectiveness of an oil-inactivated avian influenza virus (AIV) H9N2 vaccine given at different dosages and ages in broiler chicks as well as in commercial layer chicken flocks. This assessment involved challenging the chicks with the H9N2 G1 lineage avian influenza virus (A/chicken/Egypt/v1896/2022 (H9N2)) at 14 and 21 days of age alongside conducting serological monitoring in a layer flock. Phylogenetic analysis of the vaccine seed strains revealed to more than 99.00% amino acid identity to the recently isolated strains. All applied vaccination protocols successfully reduced virus shedding, clinical symptoms, and pathological damages in the trachea and lung. Birds that received a full dose of the inactivated H9N2 vaccine at zero and three days of age exhibited the strongest immune responses by 28 days even in the presence of maternal-derived antibodies. Furthermore, administering the inactivated H9N2 vaccine at three days of age provided the most substantial clinical protection against challenges occurring at various time points. Implementing a priming-boost vaccination strategy for layers provided the birds with adequate humoral immune responses to achieve sufficient pre-laying titres.

Self-assembly and immunogenicity of virus-like particles from goose astrovirus 1 structural protein following proteolytic maturation in a baculovirus system.

The efficacy of seasonal influenza vaccines varies across age groups, even in individuals with strong antibody responses. Since protection against influenza virus infection also involves cellular immunity, identifying immune markers beyond neutralizing antibodies is crucial for informing the design of next-generation vaccines. Participants were categorized by age, 28-60 and 65-85 yr, and were vaccinated with 1 of 4 influenza vaccines (Fluzone Standard-Dose [FSD], Flucelvax [FCEL], Fluzone High-Dose [FHD], or Fluad [FAD]) during the 2023-2024 influenza season. Blood samples were collected before and after vaccination and analyzed for hemagglutination inhibition (HAI) activity, antibody-secreting cells (ASCs), and HA-specific compartments: memory B cells (MBCs), circulating T follicular helper (cTfh) cells, and CD4+ T effector cells. Although all vaccines increased HAI titers, FHD, which contains 4 times more antigen content than the other vaccines, elicited superior cellular responses compared to FAD in older participants. FCEL, produced in mammalian cells, was more effective than the egg-produced FSD in younger adults. Notably, FHD triggered simultaneous ASC and cTfh1 activation in older adults, which were linked to HA-specific MBCs and long-term humoral responses. FCEL induced early and cytokine-secreting HA-specific CD4+ T cell responses in younger adults, correlating with early B cell proliferation and enhanced antibody production. These findings highlight the critical role of antigen dose and quality in inducing HA-specific cellular immunity and coordinating B and T cell activation. Synergistically engaging ASCs, cTfh, MBCs, and CD4+ T cells to enhance immunological memory and establish long-term vaccine-induced immunity should be considered in future influenza vaccine design.

Poliomyelitis, preventable only through vaccination, remains a global health concern, with wild poliovirus transmission and the emergence of vaccine-derived polioviruses. The risk of further deterioration of the situation jeopardizes efforts to eradicate polio, which has been a long-term goal for the whole world. In this systematic review, an analysis of randomized clinical trials was carried out to comprehensively assess the immunogenicity and safety of various polio immunization methods in infants. Geometric mean neutralizing antibody titers (GMT) data collected after 28-31 days after immunization were used to calculate the geometric mean titer ratio (GMR), the analysis of which showed that both inactivated polio vaccine (IPV) and Sabin strain-based inactivated polio vaccine (sIPV) as primary vaccination induce high antibody rates. Average GMR rates (CI = 0.05) for the 3 types of polio were 83.08, 33.60, and 166.30 for IPV and 234.35, 44.04, and 163.13 for sIPV, with fractional IPV showing similar results. One or two doses of IPV were insufficient to induce protection levels of antibodies against type 2 poliovirus. The novel oral polio vaccine type 2 (nOPV2) and trivalent oral polio vaccine (tOPV) also demonstrated immunogenicity in establishing immunity comparable to the inactivated vaccine; the latter exhibited an average GMR of 50.75 for serotype 2. High antibody levels were also induced by combined vaccine schedules, with sIPV-sIPV-bOPV (GMR of 1,172.7 for type 1 and 887.6 for type 3) and IPV combinations with diphtheria-tetanus-whole-cell pertussis, hepatitis B and Haemophilus influenzae type b (351.2, 258.8, and 573.6 for the 3 types) or pentavalent rotavirus vaccine (354.6, 117.7, and 540.9 for the 3 types) establishing particularly high antibody levels. Analysis of adverse events presented all vaccines to be well-tolerated and safe, with a tendency for combination vaccines to have a higher frequency of local reactions and fever. While the studies presented a diverse landscape with some existing areas of concern, this review provides structured evidence supporting the safety and immunogenicity of existing polio vaccines, as well as highlighting the interchangeability of different vaccination approaches in infants. Future research should aim to provide detailed reporting of adverse events in order to facilitate more comprehensive assessment of vaccine immunogenicity and, therefore, efficacy.

Rocky Mountain spotted fever (RMSF) caused by Rickettsia rickettsii is the most fatal tick-borne disease in people and dogs in the Americas. This pathogen is transmitted by several hard ticks: Dermacentor species, Rhipicephalus sanguineus, and Amblyomma americanum. RMSF can quickly progress to a life-threatening illness with fatalities ranging from 30% to 80%. Doxycycline is the only treatment option, and currently, no methods are available to prevent RMSF. We previously reported that vaccination with R. rickettsii whole cell antigen vaccine (WCAV) with Montanide gel adjuvant offers protection against virulent R. rickettsii infection in dogs. Here, we compared three adjuvants to optimize the safety and immunogenicity of WCAV: Alhydrogel, Montanide, and Quil A. Independent of adjuvants, all vaccinees were protected, whereas unvaccinated dogs developed the clinical disease. Vaccination reduced the pathogen to undetectable levels in blood and various tissues. An R. rickettsii-specific IgG response was observed following primary vaccination in all vaccinated groups, which augmented after booster. The vaccine with Quil A had the highest IgG response with a significant rise in CD4+ and CD8+ T cell numbers, while Montanide and Alhydrogel resulted in a balanced IgG response. IgG2 was the primary antibody detected in unvaccinated infection controls. Several systemic proinflammatory cytokines varied after infection in both vaccinees and controls. Plasma concentration of intercellular adhesion molecule 1 was higher in unvaccinated compared to vaccinees in the first 9 days after infection. This study demonstrates that the WCAV efficacy is independent of the adjuvant, although Quil A induced a higher IgG response and expansion of CD4 and CD8 T cells.

Effectiveness of high-dose influenza vaccine against hospitalisations in older adults (FLUNITY-HD): an individual-level pooled analysis.

The COVID-19 pandemic has caused many deaths worldwide, especially in patients with type 2 diabetes mellitus (DM). Owing to the association of type 2 DM with immune dysfunction, we evaluated the impact of DM on the humoral immune responses induced by inactivated (Sinovac, SV), viral vector (ChAdOx1 nCoV-19, Az) and mRNA (BNT162b2, BNT) vaccines, compared with those in non-DM individuals. The levels of anti-spike (S) and neutralizing antibodies (nAbs) against the S1 domain/receptor-binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before and after COVID-19 vaccination were determined. The immune response in non-DM individuals heterologously immunized with the Az-BNT regimen was more robust than that in those immunized with other regimens. Notably, individuals with type 2 DM presented reduced anti-S antibody levels following vaccination with the Az-BNT regimen at 30 and 90 days post-vaccination. Furthermore, a rapid decline in nAb levels in DM individuals was noted on day 90 post-boost for all regimens. Thus, a shorter interval between boosters might be necessary for DM individuals. These findings could inform the selection of optimal vaccination protocols for individuals with or without DM and contribute to the development of an efficacious COVID-19 vaccine for individuals with underlying health conditions, particularly DM.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-20324-y.

Estimates of annual effectiveness of influenza vaccination combine multiple vaccine types. Reports of brand/product-specific vaccine effectiveness (VE) of egg- and cell-culture based quadrivalent inactivated influenza vaccines (IIV4/ccIIV4) are limited. Using an observational test-negative study design, we compared effectiveness of selected IIV4 and ccIIV4 products among outpatients enrolled in the US Flu VE Network from 2014-2015 to 2018-2019. We used multivariable logistic regression to estimate product- and age-group-specific absolute and relative effectiveness of recommended, age-appropriate vaccines against symptomatic laboratory-confirmed outpatient influenza. Relative effectiveness of ccIIV4 versus IIV4 products was estimated during two seasons from 2017-2019 among participants aged ≥4 years. Pooling data from five influenza seasons when 18% and 15% of vaccinated patients had received Fluarix® Quadrivalent or Fluzone® Quadrivalent IIV4, respectively, VE against influenza was 32% for Fluarix IIV4 and 37% for Fluzone IIV4. Pooling two seasons when 11% and 28% of vaccinated patients had received ccIIV4/Flucelvax® Quadrivalent and FluLaval® Quadrivalent IIV4, respectively, VE against influenza for each product was 30%. Absolute VE compared to unvaccinated patients was lowest against influenza A(H3N2) compared to that against A(H1N1)pdm09 and each B lineage; VE point estimates were lowest among patients aged ≥50 years compared to two younger age-groups. Relative effectiveness estimates were not statistically significant, indicating similar protection across vaccine products. Comparisons of influenza vaccine products over multiple seasons showed benefit against symptomatic laboratory-confirmed outpatient influenza of both egg- and cell culture-based quadrivalent inactivated influenza vaccines, with similar absolute and relative levels of protection provided by each product.

ABSTRACT Influenza B virus (IBV) causes significant seasonal disease burden, and frequent antigenic drift limits the effectiveness of conventional vaccines. To address this, we designed mosaic haemagglutinin (HA) and neuraminidase (NA) antigens to maximize T-cell epitope coverage and incorporated them into a nasal live attenuated influenza vaccine (LAIV) platform. Using B/Victoria lineage sequences (2009-2021), mosaic HA/NA candidates were generated via an iterative genetic algorithm. BALB/c mice were randomized into PBS, conventional inactivated influenza vaccine (IIV), conventional LAIV, and mosaic-LAIV (MoBV) groups, and immunized intranasally on days 0 and 14. Immune responses were evaluated by haemagglutination inhibition (HAI), microneutralization (MN), neuraminidase inhibition (NAI), mucosal IgA by ELISA, and T-cell profiling by flow cytometry. Protective efficacy was assessed by challenge with multiple IBV strains. MoBV-induced higher cross-reactive antibody responses (HAI, MN, NAI) and markedly increased mucosal IgA, which persisted for 100 days, alongside enhanced T-cell responses. Upon challenge, MoBV improved survival to 25-100% compared with controls. These results demonstrate that MoBV elicits broad systemic and mucosal immunity, providing robust cross-lineage protection against diverse IBV strains and supporting the development of a universal influenza B vaccine.