Antibody And T Cell Response After Booster Vaccination Of COVID-19 Inactivated,Recombinant Protein,and Vector-based Vaccines

Objectives(1)To evaluate the neutralizing antibodies and T-cell response in normal healthy individuals who received two doses of inactivated vaccine following heterologous booster vaccination with recombinant subunit protein vaccine.(2)To analyze severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)spike(S)protein-specific Ig G antibodies and T-cell responses in people living with human immunodeficiency virus(HIV)(PLWH)after homologous booster vaccination with inactivated vaccine and to compare antibody and T-cell responses with those in normal healthy individuals.(3)To compare the neutralizing antibodies and T-cell response in severe acute respiratory syndrome coronavirus(SARS-CoV)survivors and normal healthy individuals after homologous booster vaccination with a vector-based vaccine and to measure the cross-reactivity of serum neutralizing against SARS-CoV-2 variants of concern.Methods(1)We conducted a follow-up study and enrolled normal healthy individuals who received two doses of Corona Vac by Sinovac six months after vaccination followed by a heterologous booster dose of ZF2001 by Anhui Longcom.Epidemiological data were obtained through a questionnaire survey.Serum samples at one month and six months and peripheral blood mononuclear cells(PBMCs)at six months after booster vaccination were collected after informed consent was signed.A pseudovirus neutralization assay was used to detect serum-neutralizing antibodies against Wild type(WT)and Omicron subvariants.Activation-induced cell marker(AIM)and intercellular cytokine staining(ICS)were used for the detection of SARS-CoV-2-specific T cells.(2)We performed a prospective cohort study and enrolled PLWH who received a homologous boost of BBIBP-Cor V by Sinopharm six months after two doses of BBIBP-Cor V.Epidemiological data were obtained by questionnaire.After signing the informed consent form,serum samples were collected before booster vaccination,and serum and PBMC samples were collected on day 56 after the booster vaccination.In addition,age-and sex-matched normal healthy individuals who received three doses of BBIBP-Cor V matched with PLWH were used as controls.Enzyme-linked immunosorbent assay(ELISA)were used to detect serum S-Ig G antibodies against WT and Omicron subvariants.An AIM assay was used to detect SARS-CoV-2-specific T cells.(3)We performed a cross-sectional study and enrolled SARS-CoV survivors and normal healthy individuals after booster vaccination with adenovirus vector vaccine(Ad5-n CoV)by Cansino Biological.Epidemiological data were obtained by questionnaire survey.Serum and PBMC samples were collected one month after booster vaccination.A pseudovirus neutralization test was used to detect neutralizing antibodies against WT,early variant strains(Beta and Delta),and Omicron subvariants in serum.AIM and ICS assays were used to detect SARS-CoV-2-specific T cells.(4)Statistical analyses and graphical plots were performed using Graph Pad Prism and R language.Categorical variables are expressed as frequencies and percentages,and the chi-square test was used for statistical analysis.Antibody titers were log10 transformed and expressed as geometric mean titer(GMT)and 95%confidence interval(CI).The number of virus-specific T cells is expressed as the median and interquartile range(IQR).The Friedman test and Kruskal?Wallis test with the false discovery rate method(FDR)were used for multiple pairs of samples and independent samples,respectively.The Wilcoxon matched-pairs signed-rank t or Mann–Whitney U test was used to compare the differences between two groups.All tests were two-sided,and P values of less than 0.05 were considered statistically significant.Results(1)Neutralizing antibodies and T-cell response following heterologous booster vaccination with ZF2001 in normal healthy individualsA total of 30 normal healthy individuals who received a heterologous booster dose of ZF2001 6 months after two doses of Corona Vac were enrolled.After one month of booster vaccination,25(83.3%)of 30 serum samples neutralized WT.Approximately30.0%-53.3%of serum samples neutralized Omicron subvariants(BA.1,BA.1.1,BA.2,BA.2.11,BA.2.12.1,BA.2.13,BA.4/BA.5 and BA.3).Compared with the GMT(308.8)of WT,neutralization activity against Omicron subvariants(BA.1,BA.1.1,BA.2,BA.2.11,BA.2.12.1,BA.2.13,BA.4/BA.5 and BA.3)decreased by 8.6-15.4-fold.Six months after booster vaccination,18(72%)of 25 boosted sera-neutralized WT with a geometric mean titer(GMT)of 57.0(95%CI 32.3–100.6),whereas only 20%-36%of sera-neutralized BA.1,BA.2,BA.2.11,BA.2.75,and BA.4/BA.5 variants.However,only one of the 25 sera neutralized BF.7,and none neutralized BQ.1.1 and XBB.Neutralizing antibody titers against WT and Omicron subvariants(BA.1,BA.2,BA.4/BA.5)decreased significantly after six months of booster vaccination compared with one month.The GMT of WT decreased more significantly by 5.4-fold,and Omicron subvariants decreased by 1.6-2.6-fold.However,72%of sera still had neutralizing activity against WT.Flow cytometry showed that AIM~+CD4~+and AIM~+CD8~+T cells were detectable in more than 60%of individuals six months after heterologous booster vaccination.SARS-CoV-2 S-specific CD4~+and CD8~+T cells producing IFN-γwere detected in 32%and 34%of individuals,respectively.(2)Antibody and T-cell response after booster vaccination of BBIBP-Cor V in PLWHWe enrolled 23 PLWH and 11 normal healthy individuals who received a BBIBP-Cor V homologous booster vaccination six months after the primary two-dose vaccination.Before booster vaccination with BBIBP-Cor V,six months after two-dose vaccination,the GMT of S-Ig G antibody titers against WT and Omicron subvariants were at low levels(1.2-7.3),and approximately 70%-80%of serum samples had no S-Ig G antibodies against WT.The S-Ig G antibody titers against WT and Omicron subvariants were significantly increased,with an approximately 19-to 121.9-fold increase after booster vaccination.However,the antibody titers against Omicron subvariants were lower than those against WT.There were no significant differences in S-Ig G antibody levels against WT,BA.1,BA.2,BA.2.12.1,and BA.4/BA.5 between PLWH and normal healthy individuals after booster vaccination(p>0.05).Flow cytometry showed that AIM~+CD4~+T cells were detectable in 65.2%(15/23)of PLWH and 81.8%(9/11)of normal healthy individuals after booster vaccination.AIM+CD8+T cells were detected in 82.6%(19/23)and 63.6%(7/11)of PLWH and normal healthy individuals,respectively.Statistical analysis showed no difference in the frequencies of T cells between PLWH and normal healthy individuals(p>0.05).(3)Antibody and T-cell response after booster vaccination of Ad5-n CoV in SARS-CoV survivorsA total of 11 SARS-CoV survivors who had received homologous booster vaccination with Ad5-n CoV were enrolled.One month after booster vaccination,8(73%),9(82%),and 7(64%)of the 11 boosted SARS-CoV survivors neutralized SARS-CoV-2 WT,Beta,and Delta,respectively,whereas only 1-3(9%-27.3%)of them had neutralizing antibodies to Omicron subvariants(BA.1,BA.2,BA.2.12.1,and BA.4/BA.5).In contrast,only 2(22%)of 9 boosted normal healthy individuals had detectable neutralizing antibodies against WT,Beta,and Delta.None of them had neutralizing antibodies to Omicron subvariants.Further comparisons of the GMT to each tested virus between boosted SARS-CoV survivors and normal healthy individuals showed that antibody levels against WT,Beta,and Delta in serum from boosted SARS-CoV survivors were significantly higher than those in normal healthy individuals(p<0.05).Flow cytometry showed that AIM~+CD4~+T cells could be detected in 72.7%(8/11)of SARS-CoV survivors and 88.9%(8/9)of normal healthy individuals after booster vaccination,while 81.8%(9/11)and 77.8%(7/9)of boosted SARS-CoV survivors and normal healthy individuals had detectable AIM~+CD8~+T cells.We found that 90.9%(10/11)of boosted SARS-CoV survivors had detectable IFN-γ~+CD4~+T cells,and 55.6%(5/9)had detectable cells in the general healthy population.SARS-CoV-2-specific IFN-γ~+CD8~+T cells were detected in 100%(11/11)of boosted SARS-CoV survivors and 77.8%(7/9)of the general healthy population.In contrast,we observed that less boosted SARS-CoV survivors and boosted normal healthy individuals had detectable S-specific TNF-α~+CD4~+or CD8~+T-cell responses.ConclusionsZF2001 heterologous booster vaccination in normal healthy individuals enhanced neutralizing antibody titers against WT one month after booster vaccination.However,the neutralization activity against Omicron subvariants was low.In addition,neutralizing antibodies against WT and Omicron subvariants were significantly decreased six months after booster vaccination compared to antibodies one month after vaccination.Homologous BBIBP-Cor V booster vaccination in PLWH induced a significantly increased antibody titer after booster vaccination,and antibody and T-cell responses were similarly observed in normal healthy individuals.Homologous Ad5-n CoV booster vaccination could induce higher and broader neutralizing antibodies in SARS-CoV survivors than in normal healthy individuals but a comparable T-cell response with SARS-CoV survivors.In conclusion,booster vaccination could enhance antibody and T-cell immune responses,but the neutralizing ability against Omicron subvariants was limited.