Spike-specific CXCR3+ TFH cells play a dominant functional role in supporting antibody responses in SARS-CoV-2 infection and vaccination

CD4+ T follicular helper (TFH) cells are required for high-quality antibody generation and maintenance. However, the longevity and functional role of these cells are poorly defined in COVID-19 convalescents and vaccine recipients. Here, we longitudinally investigated the dynamics and functional roles of spike-specific circulating TFH cells and their subsets in convalescents at the 2nd, 5th, 8th, 12th and 24th months after COVID-19 symptom onset and in vaccinees after two and three doses of inactivated vaccine. SARS-CoV-2 infection elicited robust spike-specific TFH cell and antibody responses, of which spike-specific CXCR3+ TFH cells but not spike-specific CXCR3- TFH cells and neutralizing antibodies were persistent for at least two years in more than 80% of convalescents who experienced symptomatic COVID-19, which was well coordinated between spike-specific TFH cell and antibody responses at the 5th month after infection. Inactivated vaccine immunization also induced spike-specific TFH cell and antibody responses; however, these responses rapidly declined after six months with a two-dose standard administration, and a third dose significantly promoted antibody maturation and potency. Functionally, spike-specific CXCR3+ TFH cells exhibited better responsiveness than spike-specific CXCR3- TFH cells upon spike protein stimulation in vitro and showed superior capacity in supporting spike-specific antibody secreting cell (ASC) differentiation and antibody production than spike-specific CXCR3- TFH cells cocultured with autologous memory B cells. In conclusion, spike-specific CXCR3+ TFH cells played a dominant functional role in antibody elicitation and maintenance in SARS-CoV-2 infection and vaccination, suggesting that induction of CXCR3-biased spike-specific TFH cell differentiation will benefit SARS-CoV-2 vaccine development aiming to induce long-term protective immune memory. HighlightsO_LISARS-CoV-2 infection elicited robust spike-specific TFH cell and antibody responses, which persisted for at least two years in the majority of symptomatic COVID-19 convalescent patients. C_LIO_LIInactivated vaccine immunization also elicited spike-specific TFH cell and antibody responses, which rapidly declined over time, and a third dose significantly promoted antibody maturation and potency. C_LIO_LISpike-specific CXCR3+ TFH cells exhibited more durable responses than spike-specific CXCR3- TFH cells, correlated with antibody responses and showed superior capacity in supporting ASC differentiation and antibody production than spike-specific CXCR3- TFH cells. C_LI

A mosaic-type trimeric RBD-based COVID-19 vaccine candidate induces potent neutralization against Omicron and other SARS-CoV-2 variants

Large-scale populations in the world have been vaccinated with COVID-19 vaccines, however, breakthrough infections of SARS-CoV-2 are still growing rapidly due to the emergence of immune-evasive variants, especially Omicron. It is urgent to develop effective broad-spectrum vaccines to better control the pandemic of these variants. Here, we present a mosaic-type trimeric form of spike receptor-binding domain (mos-tri-RBD) as a broad-spectrum vaccine candidate, which carries the key mutations from Omicron and other circulating variants. Tests in rats showed that the designed mos-tri-RBD, whether used alone or as a booster shot, elicited potent cross-neutralizing antibodies against not only Omicron but also other immune-evasive variants. Neutralizing antibody titers induced by mos-tri-RBD were substantially higher than those elicited by homo-tri-RBD (containing homologous RBDs from prototype strain) or the inactivated vaccine BBIBP-CorV. Our study indicates that mos-tri-RBD is highly immunogenic, which may serve as a broad-spectrum vaccine candidate in combating SARS-CoV-2 variants including Omicron.

Structure and computation-guided design of a mutation-integrated trimeric RBD candidate vaccine with broad neutralization against SARS-CoV-2

The spike (S) protein receptor-binding domain (RBD) of SARS-CoV-2 is an attractive target for COVID-19 vaccine developments, which naturally exists in a trimeric form. Here, guided by structural and computational analyses, we present a mutation-integrated trimeric form of RBD (mutI tri-RBD) as a broadly protective vaccine candidate, in which three RBDs were individually grafted from three different circulating SARS-CoV-2 strains including the prototype, Beta (B.1.351) and Kappa (B.1.617). The three RBDs were then connected end-to-end and co-assembled to possibly mimic the native trimeric arrangements in the natural S protein trimer. The recombinant expression of the mutI tri-RBD, as well as the homo-tri-RBD where the three RBDs were all truncated from the prototype strain, by mammalian cell exhibited correct folding, strong bio-activities, and high stability. The immunization of both the mutI tri-RBD and homo-tri-RBD plus aluminum adjuvant induced high levels of specific IgG and neutralizing antibodies against the SARS-CoV-2 prototype strain in mice. Notably, regarding to the "immune-escape" Beta (B.1.351) variant, mutI tri-RBD elicited significantly higher neutralizing antibody titers than homo-tri-RBD. Furthermore, due to harboring the immune-resistant mutations as well as the evolutionarily convergent hotspots, the designed mutI tri-RBD also induced strong broadly neutralizing activities against various SARS-CoV-2 variants, especially the variants partially resistant to homo-tri-RBD. Homo-tri-RBD has been approved by the China National Medical Products Administration to enter clinical trial (No. NCT04869592), and the superior broad neutralization performances against SARS-CoV-2 support the mutI tri-RBD as a more promising vaccine candidate for further clinical developments.

Immunogenicity and Safety of a SARS-CoV-2 Inactivated Vaccine (KCONVAC) in Healthy Adults: Two Randomized, Double-blind, and Placebo-controlled Phase 1/2 Clinical Trials

BackgroundThe significant morbidity and mortality resulted from the infection of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) call for urgent development of effective and safe vaccines. We report the immunogenicity and safety of a SARS-CoV-2 inactivated vaccine, KCONVAC, in healthy adults. MethodsTwo phase 1 and phase 2 randomized, double-blind, and placebo-controlled trials of KCONVAC were conducted in Chinese healthy adults aged 18 through 59 years. The phase 1 trial was conducted in a manner of dosage escalation. The first 30 participants were randomized in a ratio of 4:1 to receive two doses of either KCONVAC at 5 g per dose or placebo on Day 0 and Day 14, and the second 30 participants were randomized to receive either KCONVAC at 10 g per dose or placebo following the same procedures. The participants in the phase 2 trial were randomized in a ratio of 2:2:1 to receive either KCONVAC at 5 g or 10 g per dose, or placebo on Day 0 and Day 14, or Day 0 and Day 28. In the phase 1 trial, the primary safety endpoint was the proportion of participants experiencing adverse reactions/events within 28 days following each vaccination. Antibody response and cellular response were assayed in the phase 1 trial. In the phase 2 trial, the primary immunogenicity endpoint was the seroconversion and titre of neutralization antibody, and the seroconversion of receptor binding domain (RBD)-IgG 28 days after the second dose. FindingsIn the phase 1 trial, 60 participants were enrolled and received at least one dose of 5-g vaccine (N=24), 10-g vaccine (N=24), or placebo (N=12). In the phase 2 trial, 500 participants were enrolled and received at least one dose of 5-g vaccine (N=100 for 0/14 or 0/28 regimens), 10-g vaccine (N=100 for each regimen), or placebo (N=50 for each regimen). In the phase 1 trial, 13 (54%), 11(46%), and 7 (58%) participants reported at least one adverse event (AE), of whom 10 (42%), 6 (25%), and 6 (50%) participants reported at least one vaccination-related AE after receiving 5-g vaccine, 10-g vaccine, or placebo, respectively. In the phase 2 trial, 16 (16%), 19 (19%), and 9 (18%) participants reported at least one AE, of whom 13 (13%), 17 (17%), and 6 (12%) participants reported at least one vaccination-related AE after receiving 5-g vaccine, 10-g vaccine, or placebo at the regimen of Day 0/14, respectively. Similar results were observed in the three treatment groups of Day 0/28 regimen. All the AEs were grade 1 or 2 in intensity. No AE of grade 3 or more was reported. One SAE (foot fracture) was reported in the phase 1 trial. KCONVAC induced significant antibody response. 87{middle dot}5% (21/24) to 100% (24/24) of participants in the phase 1 trial and 83{middle dot}0% (83/100) to 100% (99/99) of participants in the phase 2 trial seroconverted for neutralising antibody to live virus, neutralising antibody to pseudovirus, and RBD-IgG after receiving two doses. Across the treatment groups in the two trials, the geometric mean titres (GMTs) of neutralising antibody to live virus ranged from 29{middle dot}3 to 49{middle dot}1 at Day 0/14 regimen and from 100{middle dot}2 to 131{middle dot}7 at Day 0/28 regimen, neutralising antibody to pseudovirus ranged from 69{middle dot}4 to 118{middle dot}7 at Day 0/14 regimen and from 153{middle dot}6 to 276{middle dot}6 at Day 0/28 regimen, and RBD-IgG ranged from 605{middle dot}3 to 1169{middle dot}8 at Day 0/14 regimen and from 1496{middle dot}8 to 2485{middle dot}5 at Day 0/28 regimen. RBD-IgG subtyping assay showed that a significant part of RBD-IgG was IgG1. The vaccine induced obvious T-cell response with 56{middle dot}5% (13/23) and 62{middle dot}5% (15/24) of participants in 5-g and 10-g vaccine groups showed positive interferon-{gamma} enzyme-linked immunospot responses 14 days after the second dose in the phase 1 trial, respectively. InterpretationKCONVAC is well tolerated and able to induce robust antibody response and cellular response in adults aged 18 to 59 years, which warrants further evaluation with this vaccine in the upcoming phase 3 efficacy trial. FundingGuandong Emergency Program for Prevention and Control of COVID-19 (2020A1111340002) and Shenzhen Key Research Project for Prevention and Control of COVID-19.

Immunogenicity and safety of a severe acute respiratory syndrome coronavirus 2 inactivated vaccine in healthy adults: randomized, double-blind, and placebo-controlled phase 1 and phase 2 clinical trials / 中华医学杂志(英文版)

BACKGROUND@#The significant morbidity and mortality resulted from the infection of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) call for urgent development of effective and safe vaccines. We report the immunogenicity and safety of an inactivated SARS-CoV-2 vaccine, KCONVAC, in healthy adults.@*METHODS@#Phase 1 and phase 2 randomized, double-blind, and placebo-controlled trials of KCONVAC were conducted in healthy Chinese adults aged 18 to 59 years. The participants in the phase 1 trial were randomized to receive two doses, one each on Days 0 and 14, of either KCONVAC (5 or 10 μg/dose) or placebo. The participants in the phase 2 trial were randomized to receive either KCONVAC (at 5 or 10 μg/dose) or placebo on Days 0 and 14 (0/14 regimen) or Days 0 and 28 (0/28 regimen). In the phase 1 trial, the primary safety endpoint was the proportion of participants experiencing adverse reactions/events within 28 days following the administration of each dose. In the phase 2 trial, the primary immunogenicity endpoints were neutralization antibody seroconversion and titer and anti-receptor-binding domain immunoglobulin G seroconversion at 28 days after the second dose.@*RESULTS@#In the phase 1 trial, 60 participants were enrolled and received at least one dose of 5-μg vaccine (n = 24), 10-μg vaccine (n = 24), or placebo (n = 12). In the phase 2 trial, 500 participants were enrolled and received at least one dose of 5-μg vaccine (n = 100 for 0/14 or 0/28 regimens), 10-μg vaccine (n = 100 for each regimen), or placebo (n = 50 for each regimen). In the phase 1 trial, 13 (54%), 11 (46%), and seven (7/12) participants reported at least one adverse event (AE) after receiving 5-, 10-μg vaccine, or placebo, respectively. In the phase 2 trial, 16 (16%), 19 (19%), and nine (18%) 0/14-regimen participants reported at least one AE after receiving 5-, 10-μg vaccine, or placebo, respectively. Similar AE incidences were observed in the three 0/28-regimen treatment groups. No AEs with an intensity of grade 3+ were reported, expect for one vaccine-unrelated serious AE (foot fracture) reported in the phase 1 trial. KCONVAC induced significant antibody responses; 0/28 regimen showed a higher immune responses than that did 0/14 regimen after receiving two vaccine doses.@*CONCLUSIONS@#Both doses of KCONVAC are well tolerated and able to induce robust immune responses in healthy adults. These results support testing 5-μg vaccine in the 0/28 regimen in an upcoming phase 3 efficacy trial.@*TRIAL REGISTRATION@#http://www.chictr.org.cn/index.aspx (No. ChiCTR2000038804, http://www.chictr.org.cn/showproj.aspx?proj=62350; No. ChiCTR2000039462, http://www.chictr.org.cn/showproj.aspx?proj=63353).

Evaluation of medium to long term efficacy of balloon dilation in the treatment of aural fullness as chief complaint / 中华耳鼻咽喉头颈外科杂志

To discuss the characteristics of symptoms improvement based on the follow-up evaluation of Eustachian tube balloon dilation medium to long-term efficacy in patients with symptomatic Eustachian tube dysfunction (SETD). Patients from 2015 to 2017 were followed up after Eustachian tube balloon dilation (with the sense of aural fullness, or tinnitus and hearing ambiguity). All participants had been done ETDQ-7 before surgery and were re-evaluated with ETDQ-7 in follow-up. The improvement of overall and individual symptoms scores in ETDQ-7, the effects of gender and the difference of scores at different stages (12-18 months, 18-24 months and 24-30 months) after the operation were analyzed. There were 29 patients, including 16 males and 13 females, whose age ranged from 20 to 62 years old. The medium to long-term score of ETDQ-7 significantly declined after surgery (27.0±7.9 . 14.1±7.5, 0.05). Among all symptoms, symptoms like "blockage feeling in ear or being like under the water, constriction feeling" , "sound of blisters or explosions in the ear" decreased obviously (0.05). Comparing different stages after surgery, the scores of ETDQ-7 existed no difference (0.05). And the difference of gender showed no significant influence on surgery effects. The subjective symptoms of patients with Eustachian tube dysfunction diagnosed with SETD can be significantly improved in the medium to long-term follow-up after Eustachian tube balloon dilation, and the degree of improvement is not linearly related to the postoperative time.

Genetic characterization of enterovirus 71 complete genome isolated in Beijing, 2008 / 中华流行病学杂志

Objective To investigate the characterization of the complete genome of EV71 in Beijing, 2008 and to provide basis for selecting appropriate virus strain to develop vaccine. Methods 12 throat swab samples were collected from children with hand-foot-mouth disease (HFMD). One sample named 08YM-3 was cultured and isolated in vero cells. Viral RNA was extracted and carried out by RT-PCR and 5' , 3' rapid amplification of eDNA ends (RACE) to obtain the sequence from 08YM-3. PCR products were cloned and analyzed. Nucleotide identity between sequences was calculated and sequence alignments were made to generate phylogenetic trees using MegAlign in DNAStar. Results 3 clones were constructed that covered EV71 complete genome. Data from sequences analysis showed that this viral strain named BJ08 shared 95.6%-96.7%, 88.3%-96.1%,78.1%-94.0%,90.8%-94.6%, 85.9%-94.1% and 90.9%-93.9% in 5' UTR, PI, P2, P3, 3' UTR region and complete genome with C4 subtype, respectively. B J08 showed low nucleotides identity (<90%) with other subtypes. Phylogenetic trees established from alignment of the complete genome and VPI region indicated that B J08 belonged to C4 subtype. BJ08 and C4 subtype strains shared the same amino acids in 6 sites in VP1 region, which were associated with EV71 subtype. There was no mutation in VP1 antigen epitope (92-107aa). Conclusion This BJ08 strain belonged to C4 subtype. Further study on EV71 complete genome would have great significance for vaccine research.

Evaluation on the analytical sensitivity of 31 HBsAg enzyme immunoassay kits / 中华流行病学杂志

Objective To study the analytical sensitivity on 31 HBsAg enzyme immunoassy (EIA) test kits.Methotis Thirty one HBsAg EIA kits produced by domestic or overseas manufactories and applied for approval during May 2007 to May 2008,were evaluated using the national reference panels.The hyperbolic curve of the log A value and log concentration for the national sensitivity standards was established.The cut-off value of each kit was substituted into the curvilinear equation to determine the analytical sensitivity which was compared between different HBsAg EIA kits.Results Twenty seven(351 lots) domestic and 4(27 lots) overseas kits were compared.Among 378 lots of the 31 HBsAg EIA kits,only 2 lots of the domestic kits had a lower sensitivity when tested with the national HBsAg reference panels,with an average approvalr ate of 99.43%(349/351).The mean analytical sensitivity of the domestic kits for adr,adw,ay serotypes were 0.307,0.419,0.513 ng/ml,respectively.There was a significant difierence between serotypes (F=97.30,P<0.01).The mean analytical sensitivity of the overseas kits for adr,adw,ay serotypes were 0.054,0.066,0.050 ng/ml respectively,with no significant difference between serotypes(F=0.65,P>0.05).The analytical sensitivity of the overseas kits for all the three serotypes was higher than that of the domestic kits(P<0.01).There was no significant difference found between the analytical sensitivities of the kits produced by the same manufactory using 30- or 60- minute incubation of detection(P>0.05).In contrast,there was significant diffefence noticed between the analytical sensitivities of the kits produced by the same manufactory when tested for 10 or 15- minute coloration of the results(P<0.01).Conclusion Analytical sensitivity of the HBsAg EIA domestic kits should be further improved,especiatry for detecting adw and ay serotypes.

Evaluation of multiplex nucleic acid testing assays for screening of hepatitis B virus DNA in blood donation process / 中华流行病学杂志

Objective To evaluate the multiplex nucleic acid testing (NAT) assays for HBV,HCV and HIV in detecting HBV DNA in plasma samples. Methods 534 plasma samples collected form several areas were detected with Abbott Architect i2000 HBsAg, ani-HBs, HBeAg, anti-HBe, anti-HBc and anti-HBc IgM diagnostic kits. HBV DNA levels of those samples were detected with Roche COBAS AmpliPrep/ COBAS TaqMan HBV Test. Two kinds of multiplex NAT assays for HBV, HCV and HIV were used to test HBV DNA of those 534 samples. Results of serology-markers and quantitative HBV DNA levels with results of NAT were compared. Results HBV DNA was positive in all 81 HBsAg, HBeAg and anti-HBc positive samples,detected by both of NAT assays. HBV DNA was positive in 11 and 19 of 200 HBsAg negative samples when detected with the two kinds of NAT assays separately. Compared with the quantitative results detected by Roche COBAS AmpliPrep/COBAS TaqMan HBV Test, the HBV DNA positive rates were 96.9% and 94.3% in 193 samples of HBV DNA levels over 500 IU/ml while 40.2% and 45.3% in 117 samples of HBV DNA levels below 500 IU/ml while 99.3% and 96.0% in 151 samples of DNA negative HBV. Conclusion There are some occult low level HBV DNA carriers with HBsAg negative results in China. NAT assays for HBV, HCV and HIV may be useful to improve the transfusion safety.

Sensitivity and specificity of 4 domestic ELISA kits for detection of hepatitis B virus markers / 中华流行病学杂志

Objective To compare and analyze the sensitivity,specificity of 4 domestic ELISA kits for detection of hepatitis B virus (HBV) markers (HBsAg,anti-HBs,HBeAg,anti-HBe,and anti-HBc).Methods Five hundred and ninety four serum samples collected from patients with chronic hepatitis B and abnormal blood donors were detected for HBV markers and by 4 domestic ELISA kits.Samples with conflicting results by different diagnostic kits were retested.Samples with the HBsAg values close to the cut-off point were detected by Abbott HBsAg confirmation kit (Architect HBsAg confirm).Sensitivity of the kits was determined,using the national sensitivity reference panels for HBsAg,anti-HBs,HBeAg,anti-HBe and anti-HBc.Results The rates of sensitivity on 4 domestic kits for detection of HBsAg were 4 to 10 times lower,and on the 4 domestic kits for detection of anti-HBs,HBeAg,anti-HBc and anti-HBc were 4 to 16 times lower,as compared to Abbott Architect kits.In addition,the domestic HBV ELISA kits had some false positive results.The total coincidence rates of HBsAg,anti-HBs,HBeAg,anti-HBe,anti-HBc were 96.46%-98.15%,94.28%-98.15%,98.15%-99.49%,90.07%-96.30%,92.09%-96.80%,respectively.Conclusion Both sensitivity and specificity of the domestically produced HBV ELISA kits should be improved.

Primary evaluation of anti-HEV diagnostic reagent by experimental infection animal model with hepatitis E virus / 中华流行病学杂志

<p><b>OBJECTIVE</b>To evaluate anti-HEV diagnostic kits by experimental infecting rhesus monkeys with HEV.</p><p><b>METHODS</b>Eight rhesus monkeys were infected with genotype 1 and 4 HEV separately. The alanine aminotransferase (ALT) level of all monkeys were detected before and after the process of infection. HEV RNA in stool specimens was tested by reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Anti-HEV IgG in serum was detected by GL-IgG and WT-IgG.</p><p><b>RESULTS</b>HEV RNA presented in the stool of all the 8 monkeys after infection. The ALT level of 1 monkey infected with genotype 1 HEV and 2 monkeys infected with genotype 4 HEV appeared abnormally after infection. Tested by GL-IgG, 2 of the 4 monkeys infected with genotype 1 HEV and 1 of 4 monkeys infected with genotype 4 HEV seroconverted to anti-HEV IgG. However, when tested by WT-IgG, all the infected monkeys seroconverted to anti-HEV IgG. The anti-HEV IgG tested by WT-IgG was positive during the whole observation period,and the anti-HEV IgG measured by GL-IgG only remained 12 weeks after infection. Detected by GL-IgG and WT-IgG, seropositive conversion of the anti-HEV IgG happened almost at the same time.</p><p><b>CONCLUSION</b>Both GL-IgG and WT-IgG could detect the anti-HEV IgG of experimentally infected rhesus monkeys but the WT-IgG had a higher sensitivity for detection of anti-HEV IgG than</p>

Expression of HBV S and preS1 fusion gene in Pichia pastoris expression system / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To clone and express the ss1 recombinant gene containing S gene and preS1 (10-50 AA) gene in P. pastoris expression system.</p><p><b>METHODS</b>The fusion gene ss1 containing the S (1-222 AA) gene and preS1 (10-50 AA) gene was constructed with PCR method. The fusion ss1 gene was cloned into the expression vector of pPIC3.5k. The linear vector DNA was transformed into the host cell of GS115 with electroporation method. After screening with G418, the product was induced to express with methanol and its antigenicity was analyzed.</p><p><b>RESULTS</b>The molecular weight of expressed ss1 protein was about 30,000 dalton. The product was reactive to anti-HBs and anti-preS1 mAb.</p><p><b>CONCLUSION</b>The fusion gene was efficiently expressed in P. pastoris expression system.The expressed products have the antigenicity of both S and preS1 protein.</p>