VacciMonitor

Vaccines for arboviral prevention: an update

2025-01-28T15:04:03+00:00

Arboviruses represent an emergent problem to global public health, with a marked increase in their propagation, related to factors such as: international travel, global trade, global warming, unplanned urbanization, and deforestation. Vaccination against arboviruses is the public health measure that will allow control and possibly eliminate diseases caused by these viruses. Different platforms have been evaluated for the design of vaccines, including inactivated virus, live attenuated virus, peptide and protein-based vaccines, viral vectors, and virus-like particles. This review provides a current summary of advancements in the established vaccines or vaccine candidates against some arboviral diseases.

Evaluation of efficacy, cell mediated and humoral immune response of two different mycoplasma vaccines in specific pathogenic free chickens

2025-01-14T15:26:21+00:00

To investigate cell mediated and humoral immune response following vaccination with live mycoplasma vaccines, 100 specific pathogenic free chickens were inoculated with two different live mycoplasma vaccines: Mycoplasma gallisepticum (ts-11) and Mycoplasma synoviae (H); another 50 chickens were kept as controls (non vaccinated chickens). To evaluate the cell mediated immune response, peripheral blood leucocytes were obtained from vaccinated and control chicken groups and the lymphocyte proliferative response and nitric oxide level were determined. The immunomodulatory cytokines expression profiles elicited by the vaccines were evaluated; the mRNA expression level of interleukin-6 and gamma interferon were determined in spleen of vaccinated specific pathogenic free chickens. In parallel, sera collected from vaccinated and control chickens were examined using an enzyme-linked immunosorbent assay antibody kit to assess the humoral immune response. A challenge test was applied at 4^th week post vaccination to all vaccinated chickens and controls against virulent strains of Mycoplasma gallisepticum and Mycoplasma synoviae. The results confirm the presence of consistent lymphoproliferation with production of interferon and nitric oxide in vitro in the two vaccinated chicken groups compared to the negative control. Moreover, the tested vaccines induced high seroconversion level with satisfactory protection (%) at 4^th week post vaccination. It was concluded that the two live mycoplasma vaccines can protect the vaccinated chickens against Mycoplasma gallisepticum and Mycoplasma synoviae infections suggesting a significant role for cell-mediated immunity.

Validation of an ELISA for the quantification of tetanus and diphtheria antitoxin in guinea pig serum

2025-02-17T19:48:02+00:00

It was validated an indirect solid phase immunoenzymatic serological assay for the quantification of tetanus and diphtheria antitoxin in guinea pig serum; a previously calibrated standard serum was used. The calibration curve presented a good linear fit and parallelism with the samples, showing R² ≥ 0.98 and CV ≤10 %. The coefficients of variation in the intra- and inter-assay precision tests were within the intervals established for each one (≤10 and ≤ 20 %, respectively). The assay proved to be specific. The accuracy of the method was demonstrated through the correlation between the serological assay and the in vivo seroneutralization assay dose L+/10/50 to determine potency of tetanus and dose Lr/100 to determine potency of diphtheria. The results obtained support the use of this analytical method based on the 3Rs principle (Reduction, Refinement and Replacement) for the evaluation of the immunological activity of vaccines containing tetanus and diphtheria toxoids.

Establishment of the area of operation for large-scale culture of Chinese hamster ovary cells to obtain a viral vaccine

2025-02-18T13:59:58+00:00

Mammalian cell culture in perfusion is characterized by higher cell densities and higher productivity. At Center of Molecular Immunology, with more than 15 years of experience in the use of this technology at the industrial level, perfusion culture of Chinese hamster ovary cells line to produce the recombinant protein rC21 (a biological raw material used in the formulation of a viral vaccine) was developed in a stirred tank bioreactor of 2,000 L effective volume. The present investigation focused on establishing the operating zone in the large-scale culture based on characterization of the process engineering, as a function of hydrodynamic parameters. A tangential velocity of 1.41 m/s was established, which implied operating a power per unit volume far from the values that cause cell damage. The size of the eddies generated by this agitation condition is larger than the diameter of mammalian cells, a condition that has no impact on cell damage according to the Kolmogorov turbulence microscale criteria. The operating zone made it possible to achieve high cell viability and kinetic parameters typical of mammalian cells.

Preliminary evaluation of humoral immune response for rabies vaccine using a developed lateral flow immunochromatographic test

2025-03-04T16:04:07+00:00

In this study, a nanogold lateral flow immunochromatographic test was developed for the detection of rabies antibodies using a panel of well-characterized clinical and experimental serum samples. The lateral flow immunochromatographic rabies virus antibody test underwent a comprehensive evaluation, including an assessment of its limit of detection, cross-reactivity, interference from potential substances, and overall performance. Sensitivity evaluation revealed a limit of detection of 0.5 IU/mL, indicating a positive result. When compared with ELISA using different sera samples, the lateral flow immunochromatographic rabies virus antibody test exhibited robust performance with a sensitivity of 91.1 %, specificity of 92 %, and an overall accuracy of 91.5 %. These results suggest that the lateral flow immunochromatographic rabies virus antibody test could be a suitable tool for evaluating antibody levels in vaccinated animals. Moreover, it provides an alternative approach for assessing the efficacy of inactivated rabies virus vaccines.

CD8+ T-cell activation after vaccination with SOBERANA®02/SOBERANA®Plus heterologous schedule in children aged 5-11 years

2025-03-10T14:22:19+00:00

In children, COVID-19 usually manifests in mild forms, but sequelae of the disease and a significant impact of pediatric populations on disease transmission have been described. In this scenario, vaccination remains the most promising alternative and the vaccine response should be characterized not only by the generation of neutralizing antibodies, but also by the ability to induce a cytotoxic T response. The aim of this study was to determine the activation of CD8⁺ T cells after vaccination with the heterologous schedule of two doses of SOBERANA^®02 and one dose of SOBERANA^®Plus in children. For this purpose, a subgroup of vaccinated children aged 5-11 years (n = 15) and a group of children recovering from moderate COVID-19 disease (n = 10) were selected as controls. Blood samples were taken 14 days after administration of SOBERANA^®Plus. Tc1, Tc2 and Tc17 subpopulations were assessed by multiparametric flow cytometry. In addition, the activation capacity of these cells and the frequency of secreting cells were determined by IFN-γ secretion assay after in vitro stimulation. As a result, higher values for the frequency of Tc1 cells (CCR4⁺CCRX3⁺CCR6^-) were observed in vaccinated compared to recovered children (p < 0.0001). Tc2 (CCR4⁺CCRX3^-CCR6^-) and Tc17 (CCR4⁺CCRX3^-CCR6⁺) cells show the highest values in recovered controls compared to vaccinated (p = 0.0318) and (p = 0.0017), respectively. After in vitro stimulation with S1 protein peptides, no differences in the frequency of activated CD8⁺CD69⁺ T lymphocytes were observed between the vaccinated group and the COVID-19 recovered control (p = 0.0563). Compared to the control group, vaccinated children showed higher levels of CD8⁺IFN-γ⁺cells (p=0.0096). In conclusion, vaccination with the heterologous SOBERANA^®02/SOBERANA^®Plus regimen activates CD8⁺T lymphocytes with polarization to Tc1 cells.

Determinants of COVID-19 pediatric vaccine hesitancy and uptake among parents from Pakistan

2025-04-01T14:42:37+00:00

Parental hesitancy to vaccinate their children may be an obstacle to achieving herd immunity against COVID-19. The current study was aimed to assess the prevalence of parental vaccine hesitancy, vaccine uptake, and factors associated with these behaviors. A web-based descriptive study design was used in this study. A self-administered questionnaire was used to collect data conveniently from Pakistani parents with children younger than 18 years. The participants self-reported the vaccination status among their children along with their socio-demographic details and attitudes towards COVID-19 vaccination in children. The association between different variables was assessed using the Chi-square test, while logistic regression analysis was performed to assess the predictors of vaccine hesitancy and uptake. Among the 386 study participants, 30 % were hesitant to be vaccinated, while 70 % got their children vaccinated against COVID-19. The younger parents, having one child (<12 years), were more hesitant to vaccinate them. Vaccine uptake was most commonly reported among participants who agreed with the safety and effectiveness of the COVID-19 vaccine in children. Health authorities should start educational campaigns to convince hesitant Pakistani parents about the benefits and safety of pediatric vaccination in order to promote the vaccination of children against COVID-19.

Serum anti-measles IgG is affected by serum iron level in patients with beta thalassemia major

2025-04-01T15:44:56+00:00

Measles remains a significant cause of morbidity and mortality despite the availability of an effective vaccine. This study compared the impact of serum iron on the immunogenicity of the measles vaccine in healthy volunteers and beta thalassemia major patients. In this case-control study, 180 beta thalassemia major patients (cases) were compared to 180 healthy volunteers (controls). The study received ethical approval, and all participants provided informed consent. IgG antibody responses to measles were measured using the ELISA method, and the association between serum iron and serum anti-measles IgG concentrations was analyzed using linear regression. The results showed that immunity to measles was achieved in 98.3 % of controls and 93.9 % of cases volunteers, with a significant difference between the two groups (p=0.026). The mean serum IgG concentration was significantly higher in controls compared to cases (296.4 ± 60.0 and 254.9 ± 35.7 IU/mL, respectively, p<0.001). Among controls, immune individuals had a significantly higher serum IgG concentration than non-immune individuals (59.3 ± 27.5 and 21.0 ± 6.9 IU/mL, respectively, p=0.034), whereas immune patients had a significantly lower mean serum IgG concentration than non-immune patients (166.8 ± 33.1 and 247.9 ± 49.2 IU/mL, respectively, p<0.001). Linear regression analysis confirmed that serum IgG concentrations were directly related to serum iron levels in controls, but indirectly associated with serum iron levels in patients. In conclusion, our results suggest that both iron deficiency and iron overload are associated with lower serum anti-measles IgG antibody levels in controls and patients, respectively. Therefore, maintaining serum iron concentrations within the normal range is recommended for a better response to vaccination.

Isolation and characterization of a recent Newcastle disease virus from infected backyard chickens in Egypt

2025-05-19T13:32:24+00:00

Genomic surveillance of Newcastle disease virus is critical for determining the genetic diversity of circulating strains and improving preparedness and response to potential outbreaks. Backyard poultry continue to present significant challenges to Newcastle disease virus control due to inadequate biosecurity, poor vaccination practices, and close interactions with migratory birds. This study was designed to isolate and characterize Newcastle disease virus from infected backyard chickens in Qalubia governorate, Egypt. The hemagglutination test and reverse transcription-polymerase chain reaction, targeting a partial segment of the F-gene, confirmed an isolate as Newcastle disease virus. Positive Newcastle disease virus isolate was sequenced and phylogenetically analyzed, revealing that it belongs to Newcastle disease virus genotype VII.1.1. It was deposited in the NCBI GenBank (CLEVB1/2024) under Accession Number PP130129. The data further confirmed that the CLEVB1 isolate had the cleavage site motif ¹¹²RRQKRF¹¹⁷, characteristic of velogenic Newcastle disease virus strains. Based on amino acid sequence comparison, the CLEVB1 isolate shared 99.2 % homology with strains teal/Egypt/SDU-3/2016 and quail/Egypt/SDU-2/2016, which were both isolated from migratory birds in 2016. Therefore, the CLEVB1 isolate is thought that it was originated from two previously identified Newcastle disease virus strains, highlighting the results of ongoing interactions between migratory birds and backyard poultry. It is recommended that continuous Newcastle disease virus surveillance and routine vaccination in backyard poultry sectors are mandatory to reduce the risk of future outbreaks.

Validation of the biphenyl colorimetric method for the determination of carbohydrate content in capsular polysaccharide of Streptococcus pneumoniae serotype 5

2025-06-09T13:53:47+00:00

Streptococcus pneumoniae is among the major pathogens that cause invasive and non-invasive infections at both ends of life: in children under 5 years of age and in people over 65 years of age. The Finlay Vaccine Institute initiated the "Pneumococcus Project", consisting of the conception and development of the Quimi-Vio® vaccine (pneumococcal vaccine) whose composition includes 2 µg of polysaccharides of serotypes 1, 5, 14, 18C, 19F, 23F and 4 μg of 6B conjugated with tetanus toxoid adsorbed on aluminum phosphate. The validation of the methods that allow the identification and quantification of the active ingredients (capsular polysaccharides in this case) present in the formulations are within the mandatory requirements for the final release of the product. During the quality control process of these polysaccharides, the content or concentration of carbohydrates is evaluated, which in the case of serotypes 1 and 5 is carried out using the biphenyl assay (m-hydroxybiphenyl colorimetric method). The objective of this work was to validate the biphenyl method to quantify carbohydrates in purified capsular polysaccharides from Streptococcus pneumoniae serotype 5, due to the importance of having a validated carbohydrate quantification method that allows it to be applied in quality control of pneumococcus active pharmaceutical ingredients. A standard solution of galacturonic acid at 1 mg/mL prepared from a Working Reference Material, galacturonic acid batch AG (1)/18, was used for the preparation of the calibration curve. An evaluation of the validation parameters was carried out: linearity, accuracy, precision and specificity, according to current requirements. The biphenyl method was specific, linear, exact and precise in the range of 0.005 - 0.10 mg/mL since the acceptance criteria established for each of them were satisfactorily met. The biphenyl or m-hydroxybiphenyl colorimetric method was valid for quality control of the purified capsular polysaccharide samples of Streptococcus pneumoniae evaluated, giving reliable results.

Selection of a culture medium to obtain outer membrane vesicles of Salmonella spp.

2025-07-01T12:26:09+00:00

Salmonellosis is an infectious disease caused by Gram negative bacteria of the Salmonella genus. Currently there are only vaccines licensed for use in humans against Salmonella Typhi. Reports in the literature about outer membrane proteins of Salmonella spp. with immunogenic activity and the existence of licensed vaccines based on outer membrane vesicles against other Gram-negative bacteria such as Neisseria meningitidis B, support the feasibility of the development of vesicle-based vaccines against Salmonella. In order to select a culture medium to obtain outer membrane vesicles of Salmonella spp., in the present work the behavior of the Salmonella Typhimurium strain ATCC-14028 was evaluated in five culture media. Two media were selected according to the biomass yield and specific growth speed. From the culture of the bacteria in the selected media, outer membrane vesicles were obtained and purified using detergent extraction. They were characterized using an analytical battery: Lowry method, polyacrylamide gel electrophoresis (12.5 %) with densitometric study, dynamic light scattering method and Z potential. The results obtained allowed the selection of the medium IVI used by the Iranian Veterinary Institute for the culture of enterobacteria, to obtain outer membrane vesicles of Salmonella spp., as it is the medium where the highest yield was obtained in biomass (11.4 g/L) and protein expression (21 protein bands in polyacrylamide gel electrophoresis.

Standardization of the Ellman method by retrogression for the quantification of maleimide groups in functionalized tetanus toxoid, for use as a carrier protein

2025-08-11T14:26:23+00:00

Conjugate vaccines have proven to be the most effective and efficient platform for preventing infections caused by encapsulated bacteria (Streptococcus pneumoniae, Haemophilus influenzae type b, among others) and, more recently, against severe acute respiratory syndrome coronavirus type 2. Among the methods used to obtain conjugate vaccines are those based on the Michael reaction, where one of the macromolecules participating in the reaction is functionalized with maleimide groups; this methodology has been used to obtain the experimental and production batches of the SOBERANA^®02 vaccine. Therefore, for proper technological performance, it is necessary to know the level of maleimide functionalization of the carrier protein. The objective of the present work was to develop and standardize an analytical procedure for the quantification of the maleimide groups that functionalize the carrier proteins, based on the Ellman method by retrogression, to be used in process controls of the SOBERANA^®02 vaccine. The main performance parameters recommended by the regulatory entity were evaluated: linearity in the working range of 0.25 - 4 µmol/L of sulfhydric groups, specificity, precision and accuracy. The statistical procedures based on descriptive and inferential analysis used allowed to determine that the procedure is specific for maleimide groups, linear (r2 > 0.98; CVf < 5%, relative standard deviation (Sbrel) < 2%, and intercept not significant), exact (percentage recovery with no significant difference with 100%) and precise under conditions of intermediate repeatability and precision.

Systematic review and meta-analysis of respiratory syncytial virus vaccines and their impact on respiratory tract infections in children under 5 years

2025-09-09T16:49:32+00:00

Respiratory syncytial virus is the main cause of respiratory tract infections in infants and children. This study systematically reviewed and conducted a meta-analysis of published data on four types of respiratory syncytial virus vaccines and their effect on respiratory tract infections. After screening of 910 studies, 16 studies involving 1189 participants aged 0 to 5 years were included in the analysis. We observed that vector-based vaccines demonstrated a significant reduction in the incidence of lower respiratory tract infections (vector based: RR: 0.47, 95% CI: 0.32–0.69; p = 0.0001), when compared to other vaccines. The study also identified that the c-DNA vaccines showed a significant increase in the incidence of upper respiratory tract infections compared to placebo groups (patients: 63.81%; placebo group: 37.25%; RR: 1.69, 95% CI: 1.17–2.46; p = 0.005). All vaccines, except c-DNA, showed reduced incidences of respiratory tract infections, with vector-based vaccines having a significant impact in reducing respiratory tract infections in infants and children.