Vaccine Research
Volume:8 Issue: 2, Summer and Autumn 2021

Sinopharm (BBIBP-CorV) is an inactivated whole-virus COVID-19 vaccine. The phase 3 trial showed an efficacy of up to 78% in preventing symptomatic COVID-19 infections. However, there have been questions raised regarding in its efficacy in older people. In this paper, several lessons are highlighted from this. Firstly, there is a need to take into account the heterogeneity of COVID-19 vaccine studies, such as representation of older people; and whether the results are generalizable to the target population of immunization programmes. Secondly, for older people, antibody responses alone may not indicate the level of protection afforded by vaccines, as cell mediated immunity is a better marker of immunity. Finally, suggestions are given to improve the immune response in older people, such as heterologous vaccination and booster doses.

The virulent Newcastle disease virus (NDV) strains cause an economically important infectious disease in poultry. The common vaccination program with genotype II NDV strains is routinely practiced to provide a better protection level against Newcastle disease (ND). Nevertheless, the emergence of new antigenic and genetic variants within the circulating NDVs raises the importance of improved control strategies. The genotype VII NDV is associated with many of the most recent outbreaks of the disease worldwide.

We evaluated the impacts of genetic divergence between the genotypes II and VII on the immunity against NDV to choose a suitable vaccine virus candidate by focusing on the F and HN proteins. Comparative bioinformatics analyses based on B- and T-cell epitopes binding affinity, protein secondary structure and physicochemical properties predictions were applied for genotypes II and VII.

Although the results showed more differences in HN protein than F protein, there was no major difference between the predicted antigenicity values, epitope regions, affinity binding to MHC-I and MHC-II, secondary structures, surface accessibility, and stability of these immunogens between genotypes II and VII.

The results suggest that genotype II-based live vaccines can induce immune responses against NDV; however, an inactivated vaccine formulated by genotype VII should be considered in combination with the traditional live vaccine to provide better protection in controlling programs against ND.

Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs) that detect pathogen associated molecular patterns and activate innate and adaptive immune system. Coronaviruses can be detected via TLRs through their biological materials such as ribonucleic acids, glycoproteins and CpG motifs. During COVID-19 pandemic, different strategies have been used for combating SARS-CoV-2 to initiate a proper and balanced immune response through TLRs or other PRRS. Understanding the trigerred TLR signaling pathways during coronavirus infections would assist to understand the control and defense mechanisms against these viral diseases. In this review, we summarize different studies on the use and function of of TLRs and their signaling pathways as vaccines/adjuvants or therapeutic agents against coronavirus infections. Since the pandemic is ongoing and there still many unknowns with respect to COVID-19 immunology, we highlight the role of TLRs and their agonists/antagonists in previous coronavirus infections, and show their potential role in the current SARS-CoV-2 immunopathology.

Corneal transplantation is among the most successful organ transplantations in humans due to its immune privilege. This owes to lack of blood and lymph vessels and the absence of major histocompatibility complex antigen presenting cells (MHC-II APCs) in the cornea. However, vaccination may trigger MHC-II response as well as antigenic cross reactivity, resulting in allograft rejection. This has been reported earlier in sporadic cases after influenza and yellow fever vaccines. With the rampant vaccination and booster doses against COVID-19, similar episodes of post-vaccination graft rejection in penetrating and lamellar keratoplasties have been reported. We had reported a case of corneal graft rejection post covid vector vaccine which recovered with steroid medications. Allograft rejection with various subtypes of vaccination opens the door to comprehend immune privilege mechanisms and prophylaxis against organ rejection. Clinicians and patients are advised to be alert to this possibility, for prompt recognition as well as treatment of post-vaccination corneal graft rejection.

Cervical cancer is one of main causes of cancer death in women, especially in   developing countries. Therefore, a low-cost broad-spectrum preventive vaccine is immediately needed. The RG-1 epitope of L2 protein is a major cross-neutralizing epitope but has low immunogenicity. This defect can be overcome by using built-in adjuvants such as TLR agonists and bacterial toxoid epitopes. To address this issue, we designed an epitope-based vaccine against HPV16 using immunoinformatic tools.

  The HPV16 RG-1 epitope was linked to built-in adjuvants including the D1 domain of flagellin and RS09 epitope as TLR agonists, and a tetanus toxoid epitope for induction of immune responses. Using immunoinformatic tools, the immunological characteristics of the construct were evaluated. In the first step, MHC-I and II binding, CD4+ T cell immunogenicity prediction, and in the second step, immunogenicity simulation of the construct were investigated.

MHC-I and II predicted epitopes showed a high potentiality to bind to mice and human MHC alleles. The results of the binding of the RG-1 epitope to MHC-I and MHC-II showed that RG-1 could induce humoral and cellular immune response while fused to three built-in adjuvants. Also, the CD4+ immunogenicity assessment results predicted that several epitopes in the designed construct, including epitopes of D1 domain and tetanus toxoid P2 epitope, behaved as potentially strong Th inducers. The immunogenicity simulation results showed that the construct could potentially provide sufficient antigen, and induce suitable humoral and cellular immune responses.

The development of new vaccine strategies has been the focus of several studies. The results showed that the designed construct can potentially provide an effective model for developing a preventive vaccine candidate against a variety of HPV genotypes.

Faecalibacterium prausnitzii is an important member of human gut microbiota with a critical function in the health of humans through the induction of inflammatory and immune responses leading to intestinal hemostasis. Microbiota-induced extracellular vesicles (EVs) were presented as a novel communication pathway between microbiota and the host that are capable of imposing positive effects on the host. Recently, EV-based treatments have been evaluated in different studies, and using EVs derived from microbiota has been recommended in recent studies as post-vaccination adjuvants. Accordingly, in the present study, the effects of various EV concentrations on the mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ) and fasting-induced adipose factor (FIAF) genes were evaluated and optimized in the human epithelial colorectal adenocarcinoma (Caco-2) cell line.

The effects of the extracted EVs from F. prausnitzii on the PPARγ and FIAF gene expression were investigated in the Caco-2 cell line via cell culture and quantitative real-time PCR. The obtained outcomes were then compared with those of our previous study (concentrations of 50 and 100 µg/ml).

It was shown that F. prausnitzii EVs (150 µg/ml) significantly increased PPARγ and FIAF gene expression in the Caco-2 cell line, relative to previous studies conducted by our team.

Considering the positive impact of F. Prausnitzii EVs on the studied genes’ expression in the present study, the EVs of the bacterium will be proposed as new post-vaccination adjuvants in people suffering from intestinal barrier disorders such as inflammatory bowel disease patients. However, more studies should be performed in this respect.

Multiple myeloma is the second most common blood malignancy which has remained incurable with current therapies. However, gene therapy using suicide viral vectors such as adenoviral vectors appear more promising than other treatments. The aim of this study was to evaluate the effects of an adenoviral vector vaccine candidate containing HSV-TK gene on tumor reduction and autophagy mechanism in animal model.

Myeloma tumor was created in mouse models using myeloma SP2/0 cell line. Three groups of negative control, positive control and target group of BALB/c mice were formed. Candidates for the Ad-HSV-tk /GCV vaccine at high titer (108) were then injected three times every 72 hours at target mice and metformin was injected into the control group for 12 consecutive days. Tumor size was measured in all 15 mice studied every three days, and finally, three days after the last dose of the vaccine, the tumors were removed for Western blotting and LC3B expression.

Examination of tumor size showed that injection of the vaccine and autophagy-inducing drug reduced tumor size compared to the negative control group. Western blotting indicated that LC3B expression was significantly higher in the target and positive control groups than in the negative control group. (Mean Diff: -0.4921; P value < 0.05; q: 7.911).

The results suggest that Ad-HSV-tk/GCV vaccine candidate was able to induce autophagy and reduce the growth of tumor cells in the animal model studied due to the ability of adenovirus to induce the immune system response, the anti-myeloma nature of adenovirus and the function of HSV-tk suicide gene

CoronaVirus Disease 2019 (COVID-19) is a viral infection caused by the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2), which is effective worldwide and has killed more than 6 million patients until today.  Hyper secretion of proinflammatory cytokines triggered by a viral infection that cannot be eliminated by the immune system and an ongoing hyper-inflammatory state primarily in the lung seem to be the main causes of death. Many mechanisms have been proposed in the pathogenesis of the cytokine storm associated with COVID-19. Poor viral clearance and persistence of a strong cytokine response despite inadequate antiviral immunity appear to be the main mechanisms underlying the pathogenesis. The diagnosis can be made easily by clinical features, imaging techniques, and nasopharyngeal PCR. The diagnosis of this hyper-inflammatory state developing in the course of COVID-19 can be made based on clinical features, abnormally high ferritin, CRP, D-dimer levels, and rapidly progressive radiological findings. In addition to the antiviral and supportive treatments developed for COVID-19, CoronaVirus Disease 2019 (COVID-19) is a viral infection caused by the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2), which is globally influential and has killed more than 6 million patients until today. Hyper-secretion of pro-inflammatory cytokines triggered by the viral infection that cannot be eliminated by the immune system and an ongoing hyper-inflammatory state primarily in the lung seem to be the major causes of death. The mechanisms proposed to explain the pathogenesis of the cytokine storm associated with COVID-19 included poor viral clearance and persistent robust cytokine response despite inadequate antiviral immunity. The diagnosis can be made easily by clinical features, imaging techniques, and nasopharyngeal PCR. The diagnosis of this hyper-inflammatory state in a patient with COVID-19 can be made with rapid deterioration in clinical features, and laboratory findings including abnormally high serum CRP, ferritin and D-dimer levels, and rapidly progressive pulmonary radiological findings. In addition to the anti-viral and supportive treatments, corticosteroids, IL-1, or IL-6 receptor blockers are frequently used to suppress the increased cytokine response. corticosteroids, IL-6 blockers, or IL-1 blockers are frequently used to suppress the increased cytokine response.