ABSTRACT
Objective:To prepare a recombinant hemagglutinin trimer (HA-Tri) vaccine against influenza viruses and to study its immunogenicity in a mouse model.Methods:A stable CHO cell line that could express HA-Tri was constructed. Western blot, single radial immunodiffusion, protein particle size detection and N-glycosylation site analysis were performed for qualitative and quantitative analysis of the recombinant protein. According to the different treatment conditions such as dosage and adjuvant, BALB/c mice were divided into 11 groups and subjected to consistent immunization procedures. Serum neutralizing antibody titers were measured on 56 d after the first immunization to evaluate the immunogenicity of HA-Tri.Results:The constructed CHO cells could secret and express HA-Tri proteins. The HA-Tri proteins were biologically active and capable of forming precipitation rings in the single radial immunodiffusion. The particle size of HA-Tri was approximately 18.79 nm and 10 N-glycosylation sites were detected, including high mannose, complex glycoforms and heterozygous glycoforms. After prime-boost immunization, there was no statistically significant difference in the titers of neutralizing antibodies induced in mice by 3.75 μg of HA-Tri in combination with RFH01 adjuvant and 15 μg of monovalent vaccine stock solution ( P=0.431 2, U=36). Serum antibody titers in the HA-Tri+ RFH01 groups were higher than those in the corresponding HA-Tri groups without RFH01 adjuvant, and the highest titer was induced in the 15 μg HA-Tri+ RFH01 group, which was 1 280. Conclusions:The recombinant HA-Tri protein was successfully prepared. HA-Tri in combination with RFH01 adjuvant could induce humoral immune responses against influenza viruses in BALB/c mice, which would provide reference for the development of influenza virus recombinant subunit vaccines.
ABSTRACT
<p><b>OBJECTIVE</b>In previous studies, we immunized mice with Ebola recombinant protein vaccine and gene vector vaccine. Both stimulated high levels of humoral immunity. In this work, we constructed a pseudovirus containing Ebola membrane proteins to verify whether the two immunization strategies can induce neutralizing antibodies in mice.</p><p><b>METHODS</b>A pseudovirus containing an Ebola virus membrane protein based on the HIV-1 viral gene sequence was constructed and evaluated using a known neutralizing antibody. The titer of the neutralizing antibody in the sera of mice immunized with the recombinant protein and the gene vector vaccine was examined using a neutralization test.</p><p><b>RESULTS</b>Ebola pseudovirus was successfully prepared and applied for neutralizing antibody detection. Immunological experiments showed that recombinant protein GP-Fc and gene vaccine pVR-modGP-Fc had good immunogenicity. The titer of the bound antibody in the serum after 8 weeks of immunization in mice was more than 1:105, and the recombinant protein induced greater humoral immunity. The results of the neutralization test based on the Ebola pseudovirus system demonstrated that both vaccines induced production of protective antibodies, while the gene vaccine induced a higher titer of neutralizing antibodies.</p><p><b>CONCLUSION</b>An Ebola pseudovirus detection system was successfully established and used to evaluate two Ebola vaccines. Both produced good immunogenicity. The findings lay the foundation for the development of new Ebola vaccines and screening for neutralizing monoclonal antibodies.</p>