Vaccine Research
Volume:1 Issue: 2, Summer and Autumn 2014

The purity and correct folding of a recombinant protein is critical for any structural, biochemical and vaccine design studies. Plasmodium vivax Duffy binding protein-II is a leading vaccine candidate for vivax malaria. In the present study, the purification process of recombinant DBP-IX (a variant form of PvDBP-II) was optimized to achieve the highest yield and purity. Moreover, naturally-acquired IgG antibodies to the expressed protein have been evaluated. DBP-IX was cloned and expressed as a his-tagged protein in E. coli. The recombinant protein was purified using Ni-NTA agarose and different purification parameters were optimized to achieve the highest yield and purity. The quality of the purified rDBP-IX was assessed by different procedures such as SDS-PAGE gel analysis in both reducing and non-reducing conditions, followed by indirect immunofluorescence antibody test and ELISA using the sera of P. vivax infected patients (n= 202). DBP-IX was successfully cloned, expressed and optimally purified. Differential mobility of the rDBP-IX on the SDS-PAGE gel in reducing and non-reducing conditions, confirmed the presence of disulphide bonds. In addition, anti-rPvDBP-IX antibody produced in mice recognized the native PvDBP-II, suggesting that epitopes in the recombinant protein were similar to the corresponding native form. Finally by performing ELISA experiments, it was demonstrated that natural P. vivax infection produces IgG against rDBP-IX (42.1%) whilecytophilicIgG1 antibody (35.4%) was the predominantly detected IgG subclass. The results indicated that the optimally-purified rDBP-IX was of a quality that could be used in vaccine development research and immunological studies of vivax malaria.

Gastric cancer, as the second reason of cancer mortality around the world, is defined as one of the serious health problems and a wide range of current research is focused to overcome the challenges relevant to its successful therapy. Employing recent approaches in the field of vaccine tumor therapy and immunotherapic strategies such as utilization of monoclonal antibodies can play significant roles in achieving efficient therapeutic means to combat the disease. Methods and In this study, computational methods including three-dimensional modeling, based on sequence combinational pattern identification together with docking procedures have been employed for design and in silico construction of prolific and effective antibody structures against HER-2 and MAGE-3 antigens. These methods led to introduction of novel and efficient anti-HER2 and anti-MAGE3 antibodies. For instance, combinational pattern of bH1 antibody (light chain) and IGG1-KAPPA 4D5 antibody (heavy chain) which obtained an exceptional score of 844.83 KJ/mol as the new candidate for cancer vaccine therapy, whereas Herceptin scored 453.4 KJ/mol. In addition, the suggested pattern for designing antibody against MAGE-3 with combination of bH1 antibody (heavy chain) and HLA-A 0201 (light chain) achieved acceptable score of 640.8 KJ/mol. It is envisaged that the results obtained from the current research could be utilized to develop efficient combined strategies for vaccine therapy of gastric cancer.

Due to their similar routes of transmission, human immunodeficiency virus (HIV) and hepatitis B virus (HBV) co-infection occurs considerably. HBV infection progresses more rapidly in HIV-infected patients. Therefore, HBV vaccination of all non-immune HIV infected patients is recommended. On the other hand, HIV-infected subjects have suboptimal responses to HBV vaccine. In this study, we aimed to determine the immune responses to standard HBV vaccination in HIV-infected patients. Fifty-six HIV infected patients who lacked evidence of either prior HBV infection or immunity were subjected to standard HBV vaccination, as 3 intramuscular injections of the standard dose (20 μg) of recombinant HBV vaccine at months 0, 1 and 6. Hepatitis B surface antibody (anti-HBs) titers were checked in all cases one month after the vaccination. A protective antibody response was defined as an anti-HBs titer of ≥10 IU/L. HBV seroprotection was observed in 56.6% of HIV-infected patients. There was no significant difference between cases with and without seroprotection regarding age, sex, possible route of HIV acquisition, CD4 count, receiving antiretroviral therapy (and its duration) and HCV infection. Our study confirms previous reports that HIV-infected patients have a lower response rate to the standard HBV vaccination compared to general population. So other strategies are needed to improve the HBV vaccine response rate in HIV cases.

Acute myeloid leukemia (AML) is a type of poor prognosis hematological malignancies characterized by heterogeneous clonal expansion of myeloid progenitors. Leukemic stem cells are thought to form the majority of a cell population in minimal residual diseases (MRDs) which are resistant to current chemotherapeutic regimens and mediate disease relapse. Current therapeutic vaccine strategies have developed to mount effective anti-leukemic immunity and eradicate the MRDs. Dendritic cells (DCs) are the most professional antigen-presenting cells to elicit efficient anti-leukemic immune responses. In this review article, we present the possibility of generating AML blast-targeted DCs, especially leukemia-derived DCs and their appropriate maturation protocols and particularly the synergistic effects of TLR agonists. We also discuss about the in vitro evaluation of the generated DCs, some reported outcomes of DC-based clinical trials as well as the possibility of combination therapy to improve the efficacy of DC-based vaccines in AML patients.

Manufacturing new Hepatitis B virus vaccines, specifically by the use of nanoparticles, is of high global interest. In this paper, a new biocompatible and biodegradable structure of nano-sized hepatitis B virus’ surface antigen (HBsAg) was generated by conjugation with dendrimers, a low cost biodegradable and biocompatible polymer. The physicochemical properties of the conjugate were characterized by zeta potential and size distribution analyses and FT-IR spectrometry. The results confirmed the conjugation between HBsAg and the dendrimers. Immunological assays indicated that the immunogenicity of the conjugated HBsAg is more than HBsAg alone. Further investigations are required to explore the mechanisms of action and the exact immunological pathway(s) of this nanocomplex vaccine candidate.

Hepatitis C (HCV) is a worldwide problem without an effective vaccine with more than 170 million chronically infected people worldwide. DNA vaccines expressing antigenic portions of the virus with adjutants have recently been developed as a novel vaccination technology. In the present study, a DNA vaccine expressing HCV core protein was developed with IL12 as a genetic adjuvant and different aspects of cell immune responses due to this vaccine were evaluated in an animal model of the infection. HCV core gene was inserted into pcDNA3. 1(-) eukaryotic expression vector and the recombinant plasmid was transformed into DH5α competent cells and a large scale DNA vaccine was prepared. The expression of the vector was verified in CHO cell line. Female C57BL/6 mice were immunized 3 times with 90 ng doses of the DNA vaccine on days 0, 14 and 28. Two weeks after the last immunization, the immune responses against HCV core antigen were assessed by lymphocyte proliferation, CTL cytotoxicity and cytokines secretion assays. The results showed that the co-administration of IL12, as a genetic adjuvant, increased the ability of HCV core DNA vaccine to enhance cytolytic T lymphocyte activity, lymphocyte proliferation and shifting of the immune response toward a T helper (Th1) pattern and altogether improved the protective immunity. This study demonstrated that intramuscular injection of HCV core DNA vaccine with a genetic adjuvant induced significant cellular immune responses in C57BL/6 mice.

Preventing communicable diseases in the armed forces (AF) of a country is considered as a national interest and has a great importance. There are limited data on the efficacy of vaccination of the navy personnel. This study was designed to evaluate both the safety and the immunogenicity of a recombinant hepatitis B (HB) vaccine made by Pasteur Institute of Iran (IPI-rHB), in this target group. In this study, all members of two navy units were enrolled. After measuring their amount of primary antibody, the subjects were selected for vaccination. Finally, 108 male volunteers were surveyed who were all between 25 to 45 years of age. Three doses of IPI-rHB vaccine (1 ml containing 20µg of the recombinant antigen) were administered to the subjects who were serologically negative for HB markers. The vaccination was given intramuscularlyvia the deltoid muscle according to the 0, 1 and 6 months schedule. The subjects were carefully monitored to record any adverse reaction of the vaccine. Blood specimens were collected from each subject, 1 month after the second and third vaccinations, in order to determine the anti-HBs antibody response to the vaccine. The obtained serum was tested by ELISA to quantify anti-HBs antibodies raised in each subject. The results showed that local pain, fever, erythema, induration, nausea, vomiting and headache were the significant side effects noted. Protective antibodies (anti-HBs) were detected with seroconversion and seroprotection rates of 52.9% and 47.1%, respectively after the second dose and seroconversion and seroprotection rates of 100% and 93.51% after the third dose of the vaccine. After completing the vaccination; in 101 (93.51%) of the participants, antibody level was greater than 10 mIU/ml and in 7 (6.48%) subjects, the antibody level was between 1 and 10 mIU/ml. After the vaccination, the geometric mean titer of anti-HB antibody was 132.85. The seroprotection rate was 93.51% among the vaccinated population and 6.48% of the participants showed seroconversion. In this study, 22 (20.37%) subjects had anti-HBs titer of 10-100 mIU/ml and 79%(73.15%) subjects had anti-HBs titer of greater than100 mIU/ml. Although immunity to HB was achieved to a protective level among all the participants, the assessment of the long term immunity in AF members after complete vaccination is recommended. the results emphasized the importance of HB vaccination in adults, especially the AF members. Moreover, it reinforced the fact that three doses of HB vaccine is necessary to increase the seropositivity rate of anti-HBsAg in this group.

Development of effective immunodiagnostic methods for detection of Mycobacterium tuberculosis infection is crucial. Serodiagnostic methods, based on antibody response to specific antigens could provide promising approaches for rapid, economical and easy to perform diagnostic tests which are crucial for tuberculosis (TB) control. In this study, the level of IgG antibody responses against recombinant TB10.4 and BacilleCalmette-Guerin (BCG) in sera from TB patients and vaccinated healthy controls were evaluated. Indirect ELISA was used to assess the anti-TB10.4 IgG levels. Serum samples were obtained from vaccinated healthy controls (65), confirmed TB positive patients (77), TB cases under antibiotic treatment (14), and cases with atypical mycobacteria infection (5). The ratio of test sera optical density to the optical density of pooled negative control was taken as cut off value. Using indirect ELISA method, anti-TB10.4 was detected in 64.5%, 93.5%, 85.7% and 100% of the sera from vaccinated healthy controls, confirmed TB positive cases, TB cases under antibiotic treatment and cases with atypical mycobacteria infection, respectively. The relative sensitivity for TB10.4 was calculated as 84.32%. In this study, the use of TB10.4 protein showed high sensitivity, but low specificity in detection of anti-M. tb antibodies in TB patients. These results suggest that further studies should be undertaken to identify the optimal combinations of antigens for the sensitive and specific serodiagnosis of TB.