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Middle East respiratory syndrome coronavirus (MERS-CoV) was identified as a novel human coronavirus and posed great threat to public health world wide,which calls for the development of effective and safe vaccine urgently. In the study, peptide epitopes tagrgeting spike antigen were predicted based on bioinformatics methods. Nine polypeptides with high scores were synthesized and linked to keyhole limpet hemocyanin (KLH). Female BALB/C mice were immunized with individual polypeptide-KLH, and the total IgG was detected by ELISA as well as the cellular mediated immunity (CMI) was analyzed using ELIs-pot assay. The results showed that an individual peptide of YVDVGPDSVKSACIEVDIQQTFFDKTWPRPIDVSKADGI could induce the highest level of total IgG as well as CMI (high frequency of IFN-γ secretion) against MERS-CoV antigen in mice. Our study identified a promising peptide vaccine candidate against MERS-CoV and provided an experimental support for bioinformatics-based design of peptide vaccine.
Subject(s)
Animals , Female , Humans , Mice , Antibodies, Viral , Allergy and Immunology , Computational Biology , Coronavirus Infections , Allergy and Immunology , Virology , Immunization , Mice, Inbred BALB C , Middle East Respiratory Syndrome Coronavirus , Genetics , Allergy and Immunology , Peptides , Genetics , Allergy and Immunology , Spike Glycoprotein, Coronavirus , Genetics , Allergy and Immunology , Viral Vaccines , Genetics , Allergy and ImmunologyABSTRACT
Objective To investigate the development strategy of novel T cell based vaccine against HCV infection.Methods BALB/c mice were primed with pSCK-based DNA vaccine and boosted with type 5 adenoviral vector-based vaccine, which expressed the structural proteins ( Core, E1 and E2) de-rived from a Chinese HCV patient (genotype 1b, Hebei strain).Enzyme linked immunospot assay (ELIS-POT) and intracellular cytokine staining ( ICS) were used to analyze the elicited antigen-specific immune re-sponses and the efficacy of cross-protection.Results Immunization of mice with the prime-boost vaccination strategy elicited stronger T cell immune responses against multiple HCV antigens than using the DNA vac-cines alone, especially the IFN-γ-secreting T cell responses against E1 protein as indicated by ELISPOT as-say.ICS data indicated that the prime-boost regimen elicited more TNF-α-producing CD4+and IFN-γ-produ-cing CD8+T cells against E1 protein and high levels of IFN-γ-producing CD4+and CD8+T cells against E2 protein in comparison with immunization with DNA vaccines.Moreover, the prime-boost vaccination was ca-pable of eliciting effective cross-protection in a surrogate challenge model based on a recombinant heterolo-gous HCV (JFH1, 2a) vaccinia virus.Conclusion The prime-boost vaccination using DNA and rAd5-based vaccine expressing HCV structural antigens induced significant cellular immune response and cross-protection in mice, suggesting the possibility of using it as a promising T cell based vaccine against HCV in-fection.
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Objective To establish an inactivated viral particle-based ELISA for the detection of antibodies against Middle East respiratory syndrome coronavirus (MERS-CoV) in serum samples collected from a MERS-CoV associated case. Methods Serum samples were collected from 10 newborns and 40 healthy adults. A viral particle-based ELISA was established by using the inactivated MERS-CoV virions as antigen. The levels of IgM and IgG antibodies in the serum samples were detected by the established ELISA and the cut-off values for positive detection were determined. Then the inactivated MERS-CoV virion-based ELISA was used to detect the antibodies against MERS-CoV in 5 serum samples collected from the first im-ported MERS case in China. Results The cut-off values of IgM and IgG antibodies in serum samples for ELISA were determined to be A450 readings of 0. 32 and 0. 42, respectively. The titers of IgM and IgG anti-bodies in serum samples collected at early admission to hospital from the first imported MERS case in China were both 1 ︰ 40. Seroconversion occurred 2 weeks after his admission to hospital with the titers of IgM and IgG reaching to 1 ︰ 320. Conclusion The inactivated MERS-CoV virion-based ELISA was established successfully and could be used for the detection of serum antibodies (IgG and IgM) in MERS associated cases.
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Objective To prepare and screen out monoclonal antibodies against the receptor bind-ing domain (RBD) of Middle East respiratory syndrome coronavirus ( MERS-CoV) spike ( S) protein in mice. Methods The RBD of MERS-CoV S protein expressed in the insect-baculovirus system was purified and then used to immunize the female BALB/ c mice. The spleen cells collected from the mice were fused with myeloma Sp2 / 0 cells. The positive hybridoma cells were obtained by using limited dilution method. Enzyme-linked immunosorbent assay ( ELISA), Western blot assay and neutralization test based on the MERS-CoV pseudovirus were performed for further screening and identification. Results Twelve strains of hybridoma cells that produced the monoclonal antibodies against RBD of MERS-CoV S protein were screened out. All of the 12 monoclonal antibodies (McAbs) could have specific reaction with the RBD of MERS-CoV S protein as indicated by the results of ELISA. Of the 12 McAbs, two were identified as the immunoglobulin M (IgM) isotype and the rest were IgG1 isotype by using double antibodies sandwich ELISA. Four McAbs including 1F1, 2E4, 3C3 and 3E6 were identified as having neutralizing activity by the neutralization test based on MERS-CoV pseudovirus. Results of the Western blot assay showed that the four McAbs (1F1, 2E4, 3C3 and 3E6) could have specific reaction with the RBD of MERS-CoV S protein, but no cross-reac-tion with that of SARS-CoV S protein. Conclusion Twelve mouse-derived McAbs against the RBD of MERS-CoV S protein were obtained. The prepared hybridoma cells showed the characteristics of high speci-ficity and stability in antibody secretion. Four out of the 12 McAbs were proved to have neutralizing activity.
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Objective To express the receptor binding domain (RBD) protein of the Middle East respiratory syndrome coronavirus (MERS-CoV) and to characterize the antigenicity of the purified recombi-nant protein. Methods The codon-optimized gene encoding the RBD protein of MERS-CoV was synthesized and then cloned into the pET30a ( +) vector to construct the recombinant expression plasmid. The trans-formed E. coli BL21 (DE3) strains carrying expression plasmid were induced by IPTG under different condi-tions. The expressed products were purified by using nickel affinity chromatography and further analyzed by SDS-PAGE and Western blot assay. Indirect ELISA was performed to analyze the antigenicity and specificity of RBD proteins expressed in prokaryotic expression systems in human serological test. Results The recom-binant RBD proteins were mainly expressed as conclusion body in an optimal induction condition of 37℃ and 0. 5 mmol/ L IPTG for 4 h. The high purified recombinant RBD proteins were obtained through denaturation and renaturation with a relative molecular mass of about 29×103 . Results of the Western blot assay showed that the recombinant RBD proteins could have specific reaction with the serum samples collected form mice with MERS-CoV infection. Indirect ELISA revealed that the RBD proteins expressed in the prokaryotic ex-pression system showed better sensitivity and specificity in the detection of antibodies against MERS-CoV in human serum samples. Conclusion This study reported the prokaryotic expression and purification of RBD protein of MERS-CoV for the first time, which might pave the way for further investigation on immunological detection of MERS-CoV and development of vaccines against MERS-CoV infection.
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Objective To express and characterize the virus-like particles( VLPs) of H5 subtype containing of hemagglutinin ( HA ) and matrix 1 ( M1 ) protein by using Baculovirus-insect cells .Methods Full length genes encoding HA protein from the A/Indonesia/05/2005(H5N1) strain and the M1 protein from the A/Anhui/01/2005 ( H5N1 ) strain were cloned into a baculovirus expression vector to construct pFBD-M1-HA.The expression of HA and M1 proteins were detected by Western blot and indirect immunoflu-orescence after the transfection of Spodoptra frugiperda (Sf9) insect cells with recombinant baculovirus.Pu-rified VLPs were analyzed by SDS-PAGE and visualized with transmission electron microscope.The biologi-cal activity of purified VLPs was detected by hemagglutination test.Results The HA and M1 proteins of H5 subtype expressed by baculovirus-insect cells could be self-assembled into the functional mature VLPs.The hemagglutination titer of VLPs was as high as 1024 HAU/50μl.Conclusion The H5 subtype VLPs as pre-pared in this study would pave a way for the development of a candidate recombinant A ( H5) vaccine.
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In this study, we evaluated the difference ot biological characteristics in the MERS-CoV infected mice model in prior to transduction with different dosage of human DPP4. Firstly, we transduced different dosage of DPP4 (high or low) into mice, and then challenged them with MERS-CoV in order to establish the model. After establishment of mice model, we observed the clinical signs of disease, virus replication, immunopathogenesis and antibody response. The results indicated that the infected mice showed typical pneumonia, virus replication, histological lesions, and neutralizing antibody production. Moreover, the high dosage group was superior to the low dosage group. Fourteen days after infection, the specific antibody to virus structural protein and neutralizing antibody were analyzed, the high dosage group induced higher level antibody. In summary, the MERS-CoV infected mice model were established prior transduction with DPP4, and the level of DPP4 influenced the clinical signs of disease, virus replication and antibody response in this model.
Subject(s)
Animals , Female , Humans , Mice , Coronavirus Infections , Genetics , Pathology , Virology , Dipeptidyl Peptidase 4 , Genetics , Metabolism , Disease Models, Animal , Mice, Inbred BALB C , Middle East Respiratory Syndrome Coronavirus , Genetics , PhysiologyABSTRACT
Objective To compare the immune effects of Coxsackievirus B3 (CVB3) capsid protein VP1 expressed bacterially, recombinant adenovirus rAd/VP1 and recombinant plasmid pcDNA3/VP1which express VP1 protein in mice. Methods After expressed in prokaryotic cells, VP1 protein was purified. Recombinant adenovirus rAd/VP1 and recombinant plasmid pcDNA3/VP1 were amplified and extracted. Six to 8-week-old, male BALB/c mice were divided into four groups randomly. Each group contained 18 mice. The mice of pcDNA3/VP1 group or VP1 protein group were immunized intramuscularly with three injections at three weeks apart, of recombinant plasmid pcDNA3/VP1 at a dose of 100 μg/mouse or recombinant protein VP1 at a dose of 50 μg/mouse. The mice of rAd/VP1 group were immunized intramuscularly twice at two weeks interval with rAd/VP1 at a dose of 1.2 × 107 PFU. The control group was mock-immunized with 100 μl of PBS intramuscularly. Mice were bled from the retroorbital sinus plexus every two weeks after each immunization. ELISA and micro-neutralization test were used to detect levels of CVB3-specific IgG antibody and neutralizing antibody titers in the sera of immunized mice. Three weeks after the last immunization, the cytotoxic T lymphocyte(CTL) killing activity of spleen lymphocytes was detected with CCK-8 assay. Subsequently, virus titers in the sera of immunized mice were determined by the 50% cell culture infective dose( CCID50 ) assay on HeLa cell monolayers and percentage of animals surviving were observed after lethal CVB3 attack over a period of 21 days. Results The titers of specific IgG antibody and neutralizing antibody in sera of VP1 protein immunized mice were higher than other groups( P ＜0.05 ). While CTL killing activity of spleen lymphocytes of VP1 protein immunized mice was lower than mice in rAd/VP1 group( P ＜0. 05). Virus titers in sera of VP1 protein immunized mice were lower than the mice in pcDNA3/VP1 or rAd/VP1 groups ( P ＜ 0.05 ), while survival rate was significantly higher than these two groups ( P ＜ 0.05 ).Conclusion VP1 protein induced higher level of humoral immune response and acquired obvious immune protection effects in mice. The immunizing potency of VP1 protein vaccine surpassed plasmid pcDNA3/VP1or recombinant adenovirus rAd/VP1. It appeared to be a promising candidate among the three different vaccines.
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Objective:To investigate the influence of B-lymphocyte chemoattractant on the immune response of CVB3 fusion gene vaccine pcDNA3/C3d3-sVP1.Methods:BALB/c mice were divided into 4 groups randomly, and injected intramuscularly with pcDNA3,pcDNA3/BLC,pcDNA3/C3d3-sVP1 and the combination with the plasmid pcDNA3/BLC and pcDNA3/C3d3-sVP1.At a certain time,they were measured for the titers for neutralizing antibodies,specific CTL cytotoxic activity.The protective efficacy of DNA vaccinations was evaluated by titers of blood viruses and survival rate.Results:The titers for antibodies increased with the time of inoculation.More specifically,the antibody titers (42.17±1.43) and the specific CTL cytotoxic activity (41.3%±3.51%) of the mice in the combination group were remarkably stronger than in the mice with pcDNA3/C3d3-sVP1(P＜0.05),but the virus titers of blood was lower.After lethal CVB3 challenge,the protection of mice from death in the combination group with the plasmid pcDNA3/BLC and pcDNA3/C3d3-sVP1 was 44%.Survival curves indicated that the survive state of combination group was better than others.Conclusion:BLC can strongly enhance the specific immunity induced by C3d3-sVP1.
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Objective To construct recombinant adenovirus Ad/MDC-VP1 and investigate its im-muno-boosting effect of the mice primed with the experimental DNA vaccine against Coxsackievirus infection. Methods The recombinant adenovirus Ad/MDC-VP1 was constructed and packaged. The Western blot analysis was used to verify the target protein. BALB/c mice were divided into four groups: Ad/MDC-VP1 group, pcDNA3/MDC-VP1 group, pcDNA3/MDC-VP1 prime-Ad/MDC-VP1 boost group and PBS group. The mice in each group were immunized intramuscularly. The titers of serum IgG and neutralizing antibody were tested by ELISA and trace neutralization assay, respectively. The lymphocytes proliferation activity and specific CTL cytotoxic activity were tested by CCK-8 assay. The mice in each group were challenged with le-thal dose of Coxsackievirus, and the assay of the serum virus titers and the observation of protection efficacy against Coxsackievirus infection were carried out. Results The recombinant adenovirus Ad/MDC-VP1 was successfully constructed and the target protein was expressed. It was observed that the titers of CVB3 VP1 specific antibody, lymphocyte stimulation index, CTL cytotoxicity activities and protection rate of the pcDNA3/MDC-VP1 prime-Ad/MDC-VP1 boost group were much higher than those of the rest groups( P < 0.05), and the titer of serum virus was lower after CVB3 challenged ( P < 0.05 ). Conclusion Both the cellular and humoral immune responses in mice could been significantly enhanced by the pcDNA3/MDC-VP1 prime-Ad/MDC-VP1 boost strategy.