Nanoadjuvants Produced by Advanced Nanochelating Technology in the Inactivated-Severe Acute Respiratory Syndrome Coronavirus-2 Vaccine Formulation: Preliminary Results on Cytokines and IgG Responses

Despite the great success of vaccines in various infectious diseases, most current vaccines are not effective enough, and on the contrary, clinically approved alum adjuvants cannot induce sufficient immune responses, including a potent cellular immune response to confer protection. In this study, we used Nanochelating Technology to develop novel nanoadjuvants to boost the potency of the alum-adjuvanted inactivated severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccine. BALB/c mice were immunized twice over 2 weeks with different doses of adjuvanted-vaccine formulations and immune responses were assessed. The analysis results of IFN-γ and IL-17 cytokines demonstrated the effectiveness of the nanoadjuvants produced by the Nanochelating Technology in shifting the alum-based vaccine toward a stronger Th1 pattern. In addition, these nanoadjuvants improved IL-2 cytokine response, which shows the efficacy of these novel formulations in inducing specific T lymphocyte proliferation. Using these nanoadjuvants increased IL-10 cytokine secretion that may be representative of a better immunoregulatory impact and may also potentially prevent immunopathology responses. Moreover, specific IgG titer analysis revealed the potency of these nanoadjuvants in improving humoral immune responses. The enzyme-linked immunosorbent assay of receptor-binding domain (RBD)-specific IgG response showed that the developed novel formulations induced strong IgG responses against this protein. This study shows that the nanostructures produced by the Advanced Nanochelating Technology have potent adjuvant effects on alum-based SARS-CoV-2 vaccines to not only compensate for alum weakness in inducing the cellular immune responses by smart regulation of the immune system but also significantly improve the humoral and cellular immune responses simultaneously.

The effect of in vitro consecutive passages and culture medium on the genetic variations in BCG Pasteur 1173P2 vaccine

Since the introduction of the Bacillus Calmette-Guérin (BCG) vaccine, the genomes of vaccine strains have undergone variations due to repeated passages in different laboratories and vaccine production facilities. Genetic variations have been considered as one of the effective factors in the BCG variable protective efficacy. Consecutive subcultures have been shown to play an essential role in causing genetic variations in several microorganisms, including Mycobacterium bovis BCG. Therefore, the world health organization (WHO) recommendation to limit the passages of master seed lot in the BCG vaccine production should be considered. Besides, the role of other external variables such as quality of the raw ingredients of the culture media, the type of the culture medium and the cultivation methods in the vaccine production has been poorly studied. Here, the effect of passages and culture medium on genetic variations in a BCG seed lot was investigated during a year. The findings of this study revealed a total of 19 variants compared to seed lot while the passages were more than the number recommended by WHO. The first culture of seed lot in the Sauton broth and Middlebrook 7H9 media, and the last subculture in Sauton broth had the least and the most variants, respectively. The observation of the higher number of variants in the last cultures on Sauton broth and Middlebrook 7H9 in comparison to the first and the middle cultures may indicate the effect of passages on the genetic variations in BCG. Additionally, more variants in BCG grown in the Sauton broth do not necessarily represent the greater ability of this medium to cause genetic mutations. For a better conclusion, it is required to examine the medium components as independent variables.

Genomic characteristics of two most widely used BCG vaccine strains: Danish 1331 and Pasteur 1173P2

Background

Bacillus Calmette–Guérin (BCG) refers to a group of vaccine strains with unique genetic characteristics. BCG is the only available vaccine for preventing tuberculosis (TB). Genetic and biochemical variations among the BCG vaccine strains have been considered as one of the significant parameters affecting the variable protective efficacy of the vaccine against pulmonary tuberculosis. To track genetic variations, here two vaccine strains (Danish 1331 and Pasteur 1173P2) popularly used according to the BCG World Atlas were subjected to a comparative analysis against the Mycobacterium tuberculosis H37Rv, Mycobacterium bovis AF2122/97, and Mycobacterium tuberculosis variant bovis BCG str. Pasteur 1173P2 reference genomes. Besides, the presence or absence of the experimentally verified human T cell epitopes was examined.

Results

Only two variants were identified in BCG Danish 1331 that have not been reported previously in any BCG strains with the complete submitted genome yet. Furthermore, we identified a DU1-like 14,577 bp region in BCG Danish 1331; The duplication which was previously seemed to be exclusive to the BCG Pasteur. We also found that 35% of the T cell epitopes are absent from both strains, and epitope sequences are more conserved than the rest of the genome.

Conclusions

We provided a comprehensive catalog of single nucleotide polymorphisms (SNPs) and short insertions and deletions (indels) in BCG Danish 1331 and BCG Pasteur 1173P2. These findings may help determine the effect of genetic variations on the variable protective efficacy of BCG vaccine strains.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08826-9.

Nanoincorporation of Plumbagin in Micelles Increase Its In Vivo Anti-Plasmodial Properties

Background:

The application of plumbagin (PLN), with a wide use in pharmaceutical science, is limited due to its low water solubility and poor bioavailability. Micelles can encapsulate hydrophobic drugs due to their hydrophobic core. The aim of this study was to develop and characterize a polymeric micelle formulation of PLN and evaluate its in vivo anti-plasmodial property.

Methods:

The study was conducted at Zanjan University of Medical Sciences, Zanjan, Iran in 2018. The triblock copolymeric micelles of PLN was prepared by e-caprolactone ring-opening polymerization, by PEG as the macroinitiator and using Sn(Oct)₂ for its catalytic properties. The synthesized nanoparticles were characterized by ¹H NMR, FTIR, GPC, AFM, and DLS. The encapsulation efficiency, drug loading capacity, and drug release were measured by UV-Vis at 520 nm. Also in vivo anti-plasmodial potential of fabricated drug loaded micelle was investigated using the 4-day suppressive test against Plasmodium berghei infection in mice.

Results:

The nanoparticles average diameter was obtained less than 80 nm. The loading capacity and encapsulation efficiencies were 18.9±1.3% and 81±0.78%, respectively. In vitro, PLN release studies showed a sustained-release pattern until 7 days in PLN-loaded micelles (M-PLN) and drug release rate in acidic condition was higher than neutral condition. In vivo, anti-plasmodial results against P. berghei displayed an 8-fold increase in anti-plasmodial activity of M-PLN when compared to free PLN at the tested dosage level on the 7^th day.

Conclusion:

Based on these results, PCL–PEG–PCL micelles have a great potential to be the carrier for PLN for the malaria targeting.

Genomic evidence for stability of the Bacillus Calmette-Guérin (BCG) vaccine strain (Pasteur 1173P2) from different batches in Iran

AIMS

Investigate the genetic stability of the BCG vaccine produced in Iran from different batches compared to the reference strain.

METHODS AND RESULTS

We comparatively analyzed the whole genome sequences of the vaccine batches from different years. Eleven vials of different batches from 2010, 2018, and 2019 were included. Complete genome analyses revealed no difference between the old (2010) and new (2018 and 2019) vaccine batches. Additionally, minor genetic changes include five single nucleotide polymorphisms (SNPs) and insertions/deletions (indels) were observed compared to the BCG Pasteur 1173P2 reference strain, which were shared among all batches. Besides, the batches were identical to the reference strain in terms of antibiotic resistance genes, prophage sequences, and clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems.

CONCLUSIONS

High genetic stability of the BCG vaccine used in the national immunization program was confirmed, which indicates the optimal conditions in the vaccine production process.

SIGNIFICANCE AND IMPACT OF THE STUDY

Genetic differences within and between vaccine strains have been declared as one of the main parameters related to the BCG vaccine variable protective efficacy. No study has been done to investigate the genetic variations of the vaccine batches at the single-base level.

Comparison of Cattle Serum Antibody Responses to Five Different Mycobacterial Antigens in an ELISA System

The presence of common zoonosis diseases caused by Mycobacterium tuberculosis complex (MTBC) and nontuberculous mycobacteria (NTM), such as Johne's and Crohn's diseases, poses a public health threat and economic losses to Iranian livestock. Therefore, the early detection of mycobacteria is of paramount importance. In this regard, enzyme-linked immunosorbent assay (ELISA) is a new, simple to use, rapid, and useful diagnostic tool. This study was performed to evaluate different crude antigens obtained from Mycobacterium species using an indirect ELISA test to identify the mycobacterial infection in infected livestock. Five different strains of Mycobacteria including M. tuberculosis, M. phlei, M. bovis, M. aviumsubspecies paratuberculosis, and M. bovis AN5 were cultured. The crude antigens in the samples were precipitated with trichloroacetic acid 4%. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis of crude antigens isolated from different Mycobacterium species was reported. The total level of protein was determined by the Lowry protein assay. After the crude antigen preparation, the ELISA test was performed and the results were compared with the purified protein derivative skin test. Data analysis was performed using SPSS software version 25. All five strains were detected in more than 92% of healthy animals. The highest sensitivity of ELISA tests was in M. bovis AN5 antigen which was greater than 83%. The highest diagnostic specificity and efficiency of assays were in M. avium subspecies paratuberculosis which was 95.83% and over 83%, respectively. Regarding the results, M. avium subspecies paratuberculosis and M. bovis AN5 antigens were promising candidates for the design of diagnostic ELISA due to their sensitivity, specificity, and efficiency.

The Effect of Antigen Dose and Antigen Presenting Process on T Cell Stimulation: A Method for Enrichment of TB10.4 Antigen-specific T-cell Clones

T-lymphocytes have critical functions in the immune responses against viral and intracellular bacterial infections as well as cancers. Antigen (Ag)-specific T-lymphocyte clones enriched and expanded in vitro are valuable tools in the study of immune responses in animal models and adoptive T-cell therapy of patients with cancer or infection. We described a method for inducing, enriching, and replicating Ag-specific poly-clonal T-cells from BALB/c mice infected with live Bacillus Calmette Guérin (BCG) bacterium. During a 7-8 days procedure, T-lymphocytes were purified from immune cells of lymph nodes stimulated with immunodominant Ag of BCG, TB10.4, and expanded by interleukin -2 cytokine. We evaluated the effect of Ag doses (1, 10, and 100 μg/mL) and exposure method of Ag presenting cells (APCs) to T-cells, on T-cells' proliferation, viability, and Interferon-gamma (IFN-γ) secretion at 2, 5, and 7 days after Ag stimulation. Increasing Ag concentration increased the average cell division, but at the highest dose of Ag (100 μg/mL), T-cell viability is decreased. Only clones induced by 10 μg/mL Ag produced a desirable amount of IFN-γ. Incubation of Ag and APCs, 24 h before T-lymphocytes addition, increased the proliferation and viability of cells. T cells are in a more favorable condition around day 5 of Ag stimulation in terms of proliferation and survival, and it is the desired time for T cell restimulation. For optimal preparation of specific T-cells for adoptive cell transfer, optimization of Ag dose, the order of APCs and T-cells exposure with Ag, and the duration of initial Ag stimulation, as well as the time for restimulation, is essential.

Comparing mRNA expression and protein abundance in MDR Mycobacterium tuberculosis: Novel protein candidates, Rv0443, Rv0379 and Rv0147 as TB potential diagnostic or therapeutic targets

Tuberculosis (TB) is a sizable public health threat in the world. This study was conducted to determine the differential protein composition between susceptible and MDRTB strains. Tuberculosis proteins were extracted by Triton™ X-114 and ammonium sulfate. Two-dimensional gel electrophoresis protein spots were selected for identification by mass spectrometry and mRNA expression levels were measured by real- time PCR. 2DE-Western blot and T cell epitope prediction for identified proteins were made by the IEDB server. The result shows at least six protein spots (Rv0147, Rv3597c, Rv0379, Rv3699, Rv1392 and Rv0443) were differentially expressed in MDRTB isolates. However, difference in mRNA gene expression was not found in the six mRNA genes. 2DE-Western blot procedures indicated strong reaction against MDRTB proteins corresponds to 13, 16 and 55 kDa areas that might be used as new diagnostic tools. In conclusion, these MDRTB proteins identified in this study could be reliable TB diagnostic candidates or therapeutic targets.

Genetic analysis of clinical and vaccine strains of Bordetella pertussis by Pulsed-Field Gel Electrophoresis (PFGE), Multi Locus Sequence Typing (MLST) and serotyping

In spite of high vaccination coverage in the Expanded Program of Immunization (EPI), pertussis has not been eradicated yet and the re-emergence of the disease is still reported worldwide. The genetic divergence study of circulating clinical strains of Bordetella pertussis among the population with high vaccination coverage is a useful tool to have an insight in the understanding of genetic patterns of this bacterium and deviation of them from vaccine strains. Different methods are accessible for studying of Bordetella pertussis that can perform appropriate assessment between populations. Strains used in this study were a collection of two pertussis vaccine strains used to create killed pertussis vaccine over years at Razi Vaccine and Serum Research Institute, 10 clinical and 2 reference strains (ATCC9797 and Tohama I) in Multilocus Sequence Typing (MLST), Pulsed-Field Gel Electrophoresis (PFGE), and serotyping. The genetic profiles of vaccine working and master seeds showed no important change(s) in frequencies of fingerprint types investigated in the vaccine strains and had homogeneity in PFGE method where the clinical isolates showed diversity in genetic profile. Serotyping method showed that all of 10 clinical strains expressing Fim 3. In MLST study, seven housekeeping genes including adk, pgm, fum C, tyr B, gly A, pep A and icd were analyzed which showed no changes in the sequence of clinical and vaccine strains with 100% homology. The genes that cause pathogenicity like ptxC, tcfA and fhaB were also evaluated and the results illustrated heterogeneity in the vaccine and circulating strains.

Improvement of Thermal Stability of BCG Vaccine

Background:

Thermal stability (TS) is a part of the BCG vaccine characterization by which the consistency of process in BCG vaccine production could be confirmed. To enhance the TS of the vaccine, some prevalent stabilizers in different concentrations were added to the final formulation of BCG bulk prior to Freeze-drying process. We found a formulation more effective than the current stabilizer for retaining the higher viability of lyophilized BCG vaccine produced by Pasteur Institute of Iran.

Methods:

In the design of experiments using Taguchi method, lactose, trehalose, glucose, dextran, and monosodium glutamate were added to the final formulation of BCG bulk prior to freeze-drying process. Viability of the samples was determined by counting the colony forming unit.

Results:

Maximum signal-to-noise ratio equal to maximum TS and viability was obtained by adding lactose, dextran, and glutamate in defined concentrations.

Conclusion:

Adding the stabilizers had a significant impact on TS of BCG vaccine to meet the quality requirements.