ABSTRACT
Objective:To express SARS-CoV nucleocapsid protein in Bac-to-Bac Baculovirus Expression System and analyze the antigenicity of the recombinant protein.Methods: The SARS-CoV nucleocapsid gene was amplified by PCR.The PCR product digested with BamHⅠand SalⅠrestriction endonucleases was cloned into vector pFastBac HTC of Bac-to-Bac Baculovirus expression system.Recombinant plasmid was transformed DH 10Bac cells to obtain the recombinant Bacmid DNA.Recombinant Bacmid DNA was transferred into Sf9 cells which were inducted to express the recombinant protein in High Five cells.After purified by Ni affinity chroma-tography ,the antigenicity of the recombinant protein was analyzed by Western blot and ELISA.Results:Recombinant plasmid was con-structed successfully.The recombinant protein with the relative molecular mass of 48 kD was efficiently expressed in High Five cells and purified successfully by Ni affinity chromatography.Western blot and ELISA analysis showed that the recombinant protein could be spe -cifically recognized by the monoclonal antibody to SARS-CoV N protein and immune serum from rabbits ,respectively.The recombinant protein can specifically reacted with serum from SARS patients ,not with serum from healthy persons and patients infected with hCoV-229 E and hCoV-OC43.Conclusion: SARS-CoV nucleocapsid protein has been expressed successfully in the Bac-to-Bac Baculovirus Expression System ,and obtained good antigenicity.It is preliminary deemed that it can't reacted with serum from patients infected with hCoV-229E and hCoV-OC43.
ABSTRACT
Severe Acute Respiratory Syndrome(SARS)is a deadly infectious disease caused by SARS Coronavirus(SARS-CoV).Inactivated SARS-CoV has been explored as a vaccine against SARS-CoV.However,safe and potent adjuvants,especially with more efficient and economical needle-free vaccination are always needed more urgently in a pandemic.The development of a safe and effective mucosal adjuvant and vaccine for prevention of emergent infectious diseases such as SARS will be an important advancement.PIKA,a stabilized derivative of Poly(I:C),was previously reported to be safe and potent as adjuvant in mouse models.In the present study,we demonstrated that the intraperitoneal and intranasal co-administration of inactivated SARS-CoV vaccine together with this improved Poly(I:C)derivative induced strong anti-SARS-CoV mucosal and systemic humoral immune responses with neutralizing activity against pseudotyped virus.Although intraperitoneal immunization of inactivated SARS-CoV vaccine alone could induce a certain level of neutralizing activity in serum as well as in mucosal sites,co-administration of inactivated SARS-CoV vaccine with PIKA as adjuvant could induce a much higher neutralizing activity.When intranasal immunization was used,PIKA was obligatorily for inducing neutralizing activity in serum as well as in mucosal sites and was correlated with both mucosal IgA and mucosal IgG response.Overall,PIKA could be a good mucosal adjuvant candidate for inactivated SARS-CoV vaccine for use in possible future pandemic.
ABSTRACT
A group of SARS-Iike coronaviruses(SL-CoV)have been identified in horseshoe bats.Despite SL-CoVs and SARS-CoV share identical genome structure and high-level sequence similarity,SL-CoV does not bind to the same cellular receptor as for SARS-CoV and the N-terminus of the S proteins only share 64% amino acid identity,suggesting there are fundamental differences between these two groups of coronaviruses.To gain insight into the basis of this difference,we established a recombinant adenovirus system expressing the S protein from SL-CoV(rAd-Rp3-S)to investigate its immune characterization.Our results showed that immunized mice generated strong humoral immune responses against the SL-CoV S protein.Moreover,a strong cellular immune response demonstrated by elevated IFN-γ and IL-6 levels was also observed in these mice.However,the induced antibody from these mice had weaker cross-reaction with the SARS-CoV S protein,and did not neutralize HIV pseudotyped with SARS-CoV S protein.These results demonstrated that the immunogenicity of the SL-CoV S protein is distinct from that of SARS-CoV,which may cause the immunological differences between human SARS-CoV and bat SL-CoV.Furthermore,the recombinant virus could serve as a potential vaccine candidate against bat SL-CoV infection.
ABSTRACT
To evaluate the immunogenicity of inactivated SARS coronavirus (SARS-CoV), three groups of rabbits were immunized three times at 2-week intervals with inactivated vaccine + adjuvant, adjuvant,and normal saline respectively. Eight batchs of serum were sampled from the auricular vein at day 7 to day 51, and specific IgG antibody titers and neutralizing antibody titers were detected by indirect ELISA and micro-cytopathic effect neutralizing test. Antibody specificity was identified by proteinchip assay.Histopathological changes were detected by H&E staining. The results showed that, rabbits in the experimental group immunized with inactivated SARS-CoV all generated specific IgG antibodies with neutralizing activity, which suggested the inactivated SARS-CoV could preserve its antigenicity well and elicit an effective humoral immune responses. The peak titer value of specific IgG antibody and neutralizing antibody reached 1:40960 and 1:2560 respectively. In the experimental group, no obvious histopathological changes was detected in the H&E stained slides of heart, spleen, kidney and testis samples, but the livers had slight histopathological changes, and the lungs presented remarkable histopathological changes. These findings are of importance for SARS-CoV inactivated vaccine development.