DNA vaccination induced protective immunity against SARS CoV-2 infection in hamsterss

The development of efficient vaccines against COVID-19 is an emergent need for global public health. The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a major target for the COVID-19 vaccine. To quickly respond to the outbreak of the SARS-CoV-2 pandemic, a nucleic acid-based vaccine is a novel option, beyond the traditional inactivated virus vaccine or recombinant protein vaccine. Here, we report a DNA vaccine containing the spike gene for delivery via electroporation. The spike genes of SARS-CoV and SARS-CoV-2 were codon optimized for mammalian cell expression and then cloned into mammalian cell expression vectors, called pSARS-S and pSARS2-S, respectively. Spike protein expression was confirmed by immunoblotting after transient expression in HEK293T cells. After immunization, sera were collected for antigen-specific antibody and neutralizing antibody titer analyses. We found that both pSARS-S and pSARS2-S immunization induced similar levels of antibodies against S2 of SARS-CoV-2. In contrast, only pSARS2-S immunization induced antibodies against the receptor-binding domain of SARS-CoV-2. We further found that pSARS2-S immunization, but not pSARS-S immunization, could induce very high titers of neutralizing antibodies against SARS-CoV-2. We further analyzed SARS-CoV-2 S protein-specific T cell responses and found that the immune responses were biased toward Th1. Importantly, pSARS2-S immunization in hamsters could induce protective immunity against SARS-CoV-2 challenge in vivo. These data suggest that DNA vaccination could be a promising approach for protecting against COVID-19.     

Novel, chimpanzee serotype 68-based adenoviral vaccine carrier for induction of antibodies to a transgene product

An E1-deletion-containing adenoviral recombinant based on the chimpanzee serotype 68 (AdC68) was developed to express the rabies virus glycoprotein. Mice immunized with this construct (AdC68rab.gp) developed antibodies to rabies virus and remained resistant to challenge with an otherwise lethal dose of rabies virus. In na?ve mice immunized intranasally, the rabies virus-specific antibody responses elicited by AdC68rab.gp were comparable with regard to both titers and isotype profiles to those induced by an adenoviral recombinant based on human serotype 5 (Adhu5) expressing the same transgene product. In contrast, subcutaneous immunization with the AdC68rab.gp vaccine resulted in markedly lower antibody responses to the rabies virus glycoprotein than the corresponding Adhu5 vaccine. Antibodies from AdC68rab.gp-immunized mice were strongly biased towards the immunoglobulin G2a isotype. The antibody response to the rabies virus glycoprotein presented by Adhu5rab.gp was severely compromised in animals preexposed to the homologous adenovirus. In contrast, the rabies virus-specific antibody response to the AdC68rab.gp vaccine was at most marginally affected by preexisting immunity to common human adenovirus serotypes, such as 2, 4, 5, 7, and 12. This novel vaccine carrier thus offers a distinct advantage over adenoviral vaccines based on common human serotypes.     

Vaccine effectiveness against SARS-CoV-2 infection or COVID-19 hospitalization with the Alpha,Delta, or Omicron SARS-CoV-2 variant: A nationwide Danish cohort study

BackgroundThe continued occurrence of more contagious Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants and waning immunity over time require ongoing reevaluation of the vaccine effectiveness (VE). This study aimed to estimate the effectiveness in 2 age groups (12 to 59 and 60 years or above) of 2 or 3 vaccine doses (BNT162b2 mRNA or mRNA-1273) by time since vaccination against SARS-CoV-2 infection and Coronavirus Disease 2019 (COVID-19) hospitalization in an Alpha-, Delta-, or Omicron-dominated period.Methods and findingsA Danish nationwide cohort study design was used to estimate VE against SARS-CoV-2 infection and COVID-19 hospitalization with the Alpha, Delta, or Omicron variant. Information was obtained from nationwide registries and linked using a unique personal identification number. The study included all previously uninfected residents in Denmark aged 12 years or above (18 years or above for the analysis of 3 doses) in the Alpha (February 20 to June 15, 2021), Delta (July 4 to November 20, 2021), and Omicron (December 21, 2021 to January 31, 2022) dominated periods. VE estimates including 95% confidence intervals (CIs) were calculated (1-hazard ratio∙100) using Cox proportional hazard regression models with underlying calendar time and adjustments for age, sex, comorbidity, and geographical region. Vaccination status was included as a time-varying exposure. In the oldest age group, VE against infection after 2 doses was 90.7% (95% CI: 88.2; 92.7) for the Alpha variant, 82.3% (95% CI: 75.5; 87.2) for the Delta variant, and 39.9% (95% CI: 26.3; 50.9) for the Omicron variant 14 to 30 days since vaccination. The VE waned over time and was 73.2% (Alpha, 95% CI: 57.1; 83.3), 50.0% (Delta, 95% CI: 46.7; 53.0), and 4.4% (Omicron, 95% CI: −0.1; 8.7) >120 days since vaccination. Higher estimates were observed after the third dose with VE estimates against infection of 86.1% (Delta, 95% CI: 83.3; 88.4) and 57.7% (Omicron, 95% CI: 55.9; 59.5) 14 to 30 days since vaccination. Among both age groups, VE against COVID-19 hospitalization 14 to 30 days since vaccination with 2 or 3 doses was 98.1% or above for the Alpha and Delta variants. Among both age groups, VE against COVID-19 hospitalization 14 to 30 days since vaccination with 2 or 3 doses was 95.5% or above for the Omicron variant. The main limitation of this study is the nonrandomized study design including potential differences between the unvaccinated (reference group) and vaccinated individuals.ConclusionsTwo vaccine doses provided high protection against SARS-CoV-2 infection and COVID-19 hospitalization with the Alpha and Delta variants with protection, notably against infection, waning over time. Two vaccine doses provided only limited and short-lived protection against SARS-CoV-2 infection with Omicron. However, the protection against COVID-19 hospitalization following Omicron SARS-CoV-2 infection was higher. The third vaccine dose substantially increased the level and duration of protection against infection with the Omicron variant and provided a high level of sustained protection against COVID-19 hospitalization among the +60-year-olds.

Mie Agermose Gram and colleagues estimate vaccine effectiveness against infection and COVID-19 hospitalization with the Alpha, Delta or Omicron variant in Denmark.     

SARS-CoV-2重组S1和S蛋白疫苗诱导保护性免疫的研究*

目的:评价新型冠状病毒(SARS-CoV-2)重组S1蛋白和S蛋白疫苗对SARS-CoV-2的免疫保护效果。方法:将SARS-CoV-2重组S1蛋白和S蛋白分别联合氢氧化铝佐剂以0.1 μg/只、1 μg/只、5 μg/只、10 μg/只不同剂量接种6~8周BALB/c纯系健康雌性小鼠。第二次免疫后采血通过酶联免疫吸附试验(ELISA)检测血清中IgG抗体效价,通过假病毒中和试验比较免疫小鼠血清对SARS-CoV-2野生型株(WT)、英国株(B.1.1.7)、巴西株(P.1)、印度株(B.1.617.2)、Mu毒株(B.1.621)和南非株(501Y.V2-1)六种假病毒毒株中和活性效价,取脾细胞通过酶联免疫斑点技术(ELISpot)检测免疫小鼠的细胞免疫水平。结果:SARS-CoV-2重组S和S1蛋白都能诱导小鼠产生较强的IgG抗体水平。免疫S1蛋白的小鼠血清对SARS-CoV-2野生型株、英国株、巴西株有明显的中和活性,免疫S蛋白的小鼠血清除了对SARS-CoV-2野生型株、英国株、巴西株有明显中和活性之外,对印度株也有明显的中和活性,两种蛋白质免疫的小鼠血清均对野生型株中和效果最强。S蛋白免疫的小鼠脾细胞能够显著诱导出γ干扰素(IFN-γ)和白介素-4(IL-4)的产生。S蛋白诱导产生的IgG抗体、中和抗体、细胞免疫水平均高于S1。结论:SARS-CoV-2重组S蛋白疫苗能够诱导产生较强的保护性免疫应答。     

Comparative immunogenicity analysis of intradermal versus intramuscular administration of SARS-CoV-2 RBD epitope peptide-based immunogen In vivo

COVID-19 pandemic has caused severe disruption of global health and devastated the socio-economic conditions all over the world. The disease is caused by SARS-CoV-2 virus that belongs to the family of Coronaviruses which are known to cause a wide spectrum of diseases both in humans and animals. One of the characteristic features of the SARS-CoV-2 virus is the high reproductive rate (R₀) that results in high transmissibility of the virus among humans. Vaccines are the best option to prevent and control this disease. Though, the traditional intramuscular (IM) route of vaccine administration is one of the effective methods for induction of antibody response, a needle-free self-administrative intradermal (ID) immunization will be easier for SARS-CoV-2 infection containment, as vaccine administration method will limit human contacts. Here, we have assessed the humoral and cellular responses of a RBD-based peptide immunogen when administered intradermally in BALB/c mice and side-by-side compared with the intramuscular immunization route. The results demonstrate that ID vaccination is well tolerated and triggered a significant magnitude of humoral antibody responses as similar to IM vaccination. Additionally, the ID immunization resulted in higher production of IFN-γ and IL-2 suggesting superior cellular response as compared to IM route. Overall, our data indicates immunization through ID route provides a promising alternative approach for the development of self-administrative SARS-CoV-2 vaccine candidates.     

Mucosally delivered E1-deleted adenoviral vaccine carriers induce transgene product-specific antibody responses in neonatal mice

E1-deleted adenoviral vectors of the human serotype 5 (AdHu5) and the chimpanzee serotype 68 (AdC68) expressing the rabies virus glycoprotein (rab.gp) were tested for induction of transgene product-specific Abs upon intranasal or oral immunization of newborn mice. Both vectors induced Abs to rabies virus that could be detected in serum and from mucosal secretions. Serum rabies virus neutralizing Ab titers sufficed to protect neonatally vaccinated mice against a subsequent challenge with rabies virus. The efficacy of the AdHu5rab.gp vector given orally to newborn mice born to AdHu5 virus-immune dams was not impaired by maternally transferred Abs to the vaccine carrier.     

Immunogenicity,effectiveness and safety of COVID-19 vaccine in older adults living in nursing homes: A real-life study

IntroductionBNT162b2 (BioNTech and Pfizer) is a nucleoside-modified mRNA vaccine that provides protection against SARS-CoV-2 infection and is generally well tolerated. However, data about its efficacy, immunogenicity and safety in people of old age or with underlying chronic conditions are scarce.PurposeTo describe BNT162b2 (BioNTech and Pfizer) COVID-19 vaccine immunogenicity, effectiveness and reactogenicity after complete vaccination (two doses), and immunogenicity and reactogenicity after one booster, in elders residing in nursing homes (NH) and healthy NH workers in real-life conditions.MethodsObservational, ambispective, multicenter study. Older adults and health workers were recruited from three nursing homes of a private hospital corporation located in three Spanish cities. The primary vaccination was carried out between January and March 2021. The follow-up was 13 months. Humoral immunity, adverse events, SARS-CoV-2 infections, hospitalizations and deaths were evaluated. Cellular immunity was assessed in a participant subset.ResultsA total of 181 residents (mean age 84.1 years; 89.9% females, Charlson index ≥2: 45%) and 148 members of staff (mean age 45.2 years; 70.2% females) were surveyed (n:329). After primary vaccination of 327 participants, vaccine response in both groups was similar; ≈70% of participants, regardless of the group, had an antibody titer above the cut-off considered currently protective (260 BAU/ml). This proportion increased significantly to ≈ 98% after the booster (p < 0.0001 in both groups). Immunogenicity was largely determined by a prior history of COVID-19 infection. Twenty residents and 3 workers were tested for cellular immunity. There was evidence of cellular immunity after primary vaccination and after booster. During the study, one resident was hospitalized for SARS-CoV-2. No SARS-CoV-2-related deaths were reported and most adverse events were mild.ConclusionsOur results suggest that the BNT162b2 mRNA COVID-19 vaccine is immunogenic, effective and safe in elderly NH residents with underlying chronic conditions.     

Efficient lung recruitment of respiratory syncytial virus-specific Th1 cells induced by recombinant bacillus Calmette-Guérin promotes virus clearance and protects from infection

Infection by the respiratory syncytial virus (RSV) can cause extensive inflammation and lung damage in susceptible hosts due to a Th2-biased immune response. Such a deleterious inflammatory response can be enhanced by immunization with formalin- or UV-inactivated RSV, as well as with vaccinia virus expressing the RSV-G protein. Recently, we have shown that vaccination with rBCG-expressing RSV Ags can prevent the disease in the mouse. To further understand the immunological mechanisms responsible for protection against RSV, we have characterized the T cell populations contributing to virus clearance in mice immunized with this BCG-based vaccine. We found that both CD4(+) and CD8(+) T cells were recruited significantly earlier to the lungs of infected mice that were previously vaccinated. Furthermore, we observed that simultaneous adoptive transfer of CD8(+) and CD4(+) RSV-specific T cells from vaccinated mice was required to confer protection against virus infection in naive recipients. In addition, CD4(+) T cells induced by vaccination released IFN-γ after RSV challenge, indicating that protection is mediated by a Th1 immune response. These data suggest that vaccination with rBCG-expressing RSV Ags can induce a specific effector/memory Th1 immune response consisting on CD4(+) and CD8(+) T cells, both necessary for a fully protective response against RSV. These results support the notion that an effective induction of Th1 T cell immunity against RSV during childhood could counteract the unbalanced Th2-like immune response triggered by the natural RSV infection.     

Yellow fever vaccine protects mice against Zika virus infection

Zika virus (ZIKV) emerged as an important infectious disease agent in Brazil in 2016. Infection usually leads to mild symptoms, but severe congenital neurological disorders and Guillain-Barré syndrome have been reported following ZIKV exposure. Creating an effective vaccine against ZIKV is a public health priority. We describe the protective effect of an already licensed attenuated yellow fever vaccine (YFV, 17DD) in type-I interferon receptor knockout mice (A129) and immunocompetent BALB/c and SV-129 (A129 background) mice infected with ZIKV. YFV vaccination provided protection against ZIKV, with decreased mortality in A129 mice, a reduction in the cerebral viral load in all mice, and weight loss prevention in BALB/c mice. The A129 mice that were challenged two and three weeks after the first dose of the vaccine were fully protected, whereas partial protection was observed five weeks after vaccination. In all cases, the YFV vaccine provoked a substantial decrease in the cerebral viral load. YFV immunization also prevented hippocampal synapse loss and microgliosis in ZIKV-infected mice. Our vaccine model is T cell-dependent, with AG129 mice being unable to tolerate immunization (vaccination is lethal in this mouse model), indicating the importance of IFN-γ in immunogenicity. To confirm the role of T cells, we immunized nude mice that we demonstrated to be very susceptible to infection. Immunization with YFV and challenge 7 days after booster did not protect nude mice in terms of weight loss and showed partial protection in the survival curve. When we evaluated the humoral response, the vaccine elicited significant antibody titers against ZIKV; however, it showed no neutralizing activity in vitro and in vivo. The data indicate that a cell-mediated response promotes protection against cerebral infection, which is crucial to vaccine protection, and it appears to not necessarily require a humoral response. This protective effect can also be attributed to innate factors, but more studies are needed to strengthen this hypothesis. Our findings open the way to using an available and inexpensive vaccine for large-scale immunization in the event of a ZIKV outbreak.     

Immunological responses of hamsters in the acquired immune state to Mycoplasma pneumoniae infection

Protective effects of vaccination of hamsters against Mycoplasma pneumoniae infection, evaluated according to the recovery of mycoplasmas and histopathological changes in the respiratory tract after challenge infection, persisted for at least 6 months after the final vaccination. Serum antibody levels reached a maximum in the second week after the last vaccination and decreased markedly between the first and the third months, but increased again in sera obtained from animals given booster injections. Metabolism-inhibiting antibodies were detected in bronchial washings of animals showing high resistance obtained by vaccinal or passive immunization. Antiserum transfer was also effective for protection but cell-mediated immune responses were not demonstrated in any animals up to 6 months after the vaccination. Even after 10 months, suppression of both mycoplasmal proliferation and lung lesions was apparent, and a single dose of the vaccine induced a significant booster effect. These findings suggest that (1) humoral immunity is more important than cell-mediated immunity in resistance of hamsters to M. pneumoniae pneumonia, and (2) the antibody secreted in the respiratory tract may be involved in the local defense mechanisms.     

Dynamics of autoantibodies in elderly persons in the process of vaccination with Grippol and multicomponent vaccine VP-4

The dynamics of antibodies to organ specific and organ nonspecific antigens in the process of combined immunization with Grippol, an influenza polymer subunit vaccine and polycomponent vaccine VP-4 used for prophylaxis of acute respiratory infections, was under study. Persons aged 65 years and older were vaccinated. Grippol alone was introduced in a single subcutaneous injection into 92 persons and Grippol in combination with vaccine VP-4--to 103 persons. B[symbol: see text]-4 Vaccine was introduced intranasally and orally (6-8 doses). The administration of vaccine VP-4 was started simultaneously with vaccination with Grippol. Prior to immunization and 1 and 5 months later autoantibodies to the following antigens were detected: DNA (native and denaturated), collagen, elastin, myelin basic protein, microsomal fractions of kidneys, lungs, heart, liver, intestine, pituitary body, thyroid gland, pancreas, adrenal glands, ovaries, mucous and muscular layers of stomach. The number of persons with the level of antibodies at least to one of the antigens under study exceeding the normal values prior to vaccination varied from 19.4 +/- 8.6% to 41.5 +/- 7.7%, the average values of positive sera being 0.26 +/- 0.05 to 0.32 +/- 0.08 delta OD. One and 5 months after vaccination both values varied within the same limits in both groups. Immunization with Grippol as well as with its combination with vaccine VP-4 was found to increased spectrum of antibodies to tissue antigens and their increased content. The data give evidence that Grippol and vaccine Vp-4, introduced according to the immunization schedule used in these experiments, do not induce development of autoimmune processes.     

Induction of CD8+ T cells to an HIV-1 antigen through a prime boost regimen with heterologous E1-deleted adenoviral vaccine carriers

E1-deleted adenoviral recombinants most commonly based on the human serotype 5 (AdHu5) have been shown thus far to induce unsurpassed transgene product-specific CD8(+) T cell responses. A large percentage of the adult human population carries neutralizing Abs due to natural exposures to AdHu5 virus. To circumvent reduction of the efficacy of adenovirus (Ad) vector-based vaccines by neutralizing Abs to the vaccine carrier, we developed E1-deleted adenoviral vaccine carriers based on simian serotypes. One of these carriers, termed AdC68, expressing a codon-optimized truncated form of gag of HIV-1 was shown previously to induce a potent transgene product-specific CD8(+) T cell response in mice. We constructed a second chimpanzee adenovirus vaccine vector, termed AdC6, also expressing the truncated gag of HIV-1. This vector, which belongs to a different serotype than the AdC68 virus, induces high frequencies of gag-specific CD8(+) T cells in mice including those pre-exposed to AdHu5 virus. Generation of an additional E1-deleted adenoviral vector of chimpanzee origin allows for sequential booster immunizations with heterologous vaccine carriers. In this study, we show that such heterologous prime boost regimens based on E1-deleted adenoviral vectors of different serotypes expressing the same transgene product are highly efficient in increasing the transgene product-specific CD8(+) T cell response. They are equivalent to sequential vaccinations with an E1-deleted Ad vector followed by booster immunization with a poxvirus vector and they surpass regimens based on DNA vaccine prime followed by a recombinant adenoviral vector boost.     

Do we need nasal vaccines against COVID 19 to suppress the transmission of infections?

Covid-19 vaccines have within the first year prevented about 14 million deaths but did not induce a strong mucosal immune response. Data from US, UK, Singapore and Israel showed a variable and mostly modest effects of vaccination on virus excretion during breakthrough infections. Contact studies showed decreased transmission of infection from vaccinated index cases, but the effect varied according to dominant virus type, with study type and the nature of the contact group and diminished with time after vaccination. Some researchers suspect that it is unlikely to stop the pandemic with injected vaccines alone. Promising animal experiments were conducted with mucosal vaccines. Mice nasally immunized with a chimpanzee adenovirus vector mounted a mucosal immune response, were protected against viral challenge after a single vaccine dose and suppressed nasal replication of the challenge virus. Phage T4 expressing SARS-CoV-2 spike and nucleocapsid induced a sterilizing lung immunity in nasally vaccinated mice. Also hamsters intranasally immunized with the prefusion-stabilized spike protein showed no infectious virus in nasal turbinates upon challenge. Other studies showed that intranasal vaccination with an adenovirus vaccine reduced but did not eliminated viral transmission from infected to naïve hamsters. Intranasal vaccination of rhesus macaques with adenovirus vaccines also substantially reduced or even suppressed viral replication in the upper and lower respiratory tract. Human data on mucosal SARS-CoV-2 vaccines are so far limited to safety and immunogenicity studies. Aerosolized adenovirus vaccines given either as a booster or as primary immunization were safe and induced similar or superior immune response than injected vaccines while an aerosolized influenza vectored vaccine induced only a weak humoral and cellular immune response. Overall 100 mucosal SARS-CoV-2 vaccines are in development and 20 are in clinical trials. First human trials demonstrate that this will not be an easy task.     

Protection of inactivated influenza virus vaccine against lethal influenza virus infection in diabetic mice

Influenza virus infection frequently causes complications and some excess mortality in the patients with diabetes. Vaccination is an effective measure to prevent influenza virus infection. In this paper, antibody response and protection against influenza virus infection induced by vaccination were studied in mouse model of diabetes. Healthy and diabetic BALB/c mice were immunized once or twice with inactivated influenza virus vaccine at various dosages. Four weeks after the first immunization or 1 week after the second immunization, the mice were challenged with influenza virus at a lethal dose. The result showed that the antibody responses in diabetic mice were inhibited. Immunization once with high dose or twice with low dose of vaccine provided full protection against lethal influenza virus challenge in diabetic mice, however, in healthy mice, immunization only once with low dose provided a full protection.     

Recipients of COVID-19 vaccines face challenges of SARS-CoV-2 variants

The coronavirus disease 19 (COVID-19) has been rampant since 2019, severely affecting global public health, and causing 5.75 million deaths worldwide. So far, many vaccines have been developed to prevent the infection of SARS-CoV-2 virus. However, the emergence of new variants may threat vaccine recipients as they might evade immunological surveillance that depends on the using of anti-SARS-CoV-2 antibody to neutralize the viral particles. Recent studies have found that recipients who received two doses of vaccination plus an additional booster shoot were able to quickly elevate neutralization response and immune response against wild-type SARS-CoV-2 virus and some initially appeared viral variants. In this review, we assessed the real-world effectiveness of different COVID-19 vaccines by population studies and neutralization assays and compared neutralization responses of booster vaccines in vitro. Finally, as the efficacy of COVID-19 vaccine is expected to decline over time, continued vaccination should be considered to achieve a long-term immune protection against coronavirus.     

Age Dependence of Immunity Induced by a Candidate Universal Influenza Vaccine in Mice

Influenza has a major impact on the elderly due to increased susceptibility to infection with age and poor response to current vaccines. We have studied universal influenza vaccine candidates based on influenza A nucleoprotein and matrix 2 (A/NP+M2). Long-lasting protection against influenza virus strains of divergent subtypes is induced, especially with mucosal immunization. Here, we tested universal vaccination in BALB/c mice of different ages. Vaccination used intramuscular DNA priming to A/NP+M2 followed by intranasal (i.n.) boosting with recombinant adenoviruses (rAd) expressing the same antigens, or only A/NP+M2-rAd given i.n. Antigen-specific systemic antibody responses were induced in young, middle-aged, and elderly mice (2, 11–17, and 20 months old, respectively), but decreased with age. Antibody responses in bronchoalveolar lavage (BAL) were detected only in young mice. Antigen-specific T cell responses were seen in young and middle-aged but not elderly mice. A/NP+M2 vaccination by the two regimens above protected against stringent challenge in young and middle-aged mice, but not in elderly mice. However, mice vaccinated with A/NP-rAd or A/M2-rAd during their youth were partially protected against challenge 16 months later when they were elderly. In addition, a regimen of two doses of A/NP+M2-rAd given i.n. one month apart beginning in old age protected elderly mice against stringent challenge. This study highlights the potential benefit of cross-protective vaccines through middle age, and suggests that their performance might be enhanced in elderly individuals who had been exposed to influenza antigens early in life, as most humans have been, or by a two-dose rAd regimen given later in life.     

Relative deficiency in interferon-γ-secreting CD4+ T cells is strongly associated with poorer COVID-19 vaccination responses in older adults

Although the two-dose mRNA vaccination regime provides protection against SARS-CoV-2, older adults have been shown to exhibit poorer vaccination responses. In addition, the role of vaccine-induced T-cell responses is not well characterised. We aim to assess the impact of age on immune responses after two doses of the BNT162b2 mRNA vaccine, focussing on antigen-specific T-cells. A prospective 3-month study was conducted on 15 young (median age 31 years, interquartile range (IQR) 25–35 years) and 14 older adults (median age 72 years, IQR 70–73 years). We assessed functional, neutralising antibody responses against SARS-CoV-2 variants using ACE-2 inhibition assays, and changes in B and T-cell subsets by high-dimensional flow cytometry. Antigen-specific T-cell responses were also quantified by intracellular cytokine staining and flow cytometry. Older adults had attenuated T-helper (Th) response to vaccination, which was associated with weaker antibody responses and decreased SARS-CoV-2 neutralisation. Antigen-specific interferon-γ (IFNγ)-secreting CD4+ T-cells to wild-type and Omicron antigens increased in young adults, which was strongly positively correlated with their neutralising antibody responses. Conversely, this relationship was negative in older adults. Hence, older adults' relative IFNγ-secreting CD4+ T cell deficiency might explain their poorer COVID-19 vaccination responses. Further exploration into the aetiology is needed and would be integral in developing novel vaccination strategies and improving infection outcomes in older adults.     

两种表达系统来源新冠病毒RBD蛋白免疫小鼠后的IgG抗体水平对比研究

当前新冠肺炎疫情仍在全球蔓延,给中国及世界的公共卫生安全和经济发展带来了严峻挑战。SARS-CoV-2病毒入侵机体的关键过程是刺突蛋白受体结合域RBD通过结合宿主细胞ACE2受体实现感染,而此过程与病原快速检测、疫苗以及药物干预等主要抗病毒策略的研究与开发密切相关。因此,本研究旨在比较哺乳细胞和昆虫细胞重组表达来源的新冠病毒刺突蛋白受体结合结构域RBD免疫小鼠后产生IgG抗体水平的变化,评估不同来源和不同剂量抗原的抗体滴度水平和持续时间,希望将有助于疫苗、药物以及病原检测等相关研究。通过SDS-PAGE和质谱技术鉴定出昆虫和哺乳动物细胞表达系统制备的bRBD和hRBD蛋白质的分子量略有差异,主要为糖基化修饰不同所致;流式细胞术检测发现,bRBD和hRBD与ACE2受体过表达细胞结合率分别为88.5%和92.7%,表明二者均具有较好的活性;利用Quick Antibody免疫佐剂通过肌肉注射对Balb/c小鼠进行免疫接种,设置10μg、20μg 2个免疫抗原的剂量,共接种2次,并在初次免疫后第2、4、6、8、12、24周从尾部取血,分离获得血清;酶联免疫吸附结果显示,10μg和20μg的...     

Determination of the optimal inoculation dose of Brucella chemical vaccine

Brucellosis chemical vaccine, when injected intramuscularly, proved to be low-reactogenic, postvaccinal reactions, both systemic and local, becoming less frequent and intense with the decrease of the dose from 2 to 0.5 mg. The highest antigenic and immunogenic activity was observed with a dose of 1 mg; out of 4 tested doses this dose produced the highest percentage of seroconversions, the highest titers of agglutinins and the longest time of their persistence in the subjects. When introduced in doses of up to 2 mg, brucellosis chemical vaccine did not induce pronounced sensitization. A high degree of correlation between the indices of seroconversion frequency in Wright's agglutination test and Huddleson's test was established after vaccination with all tested doses. This fact indicates that one of these tests can be used for the assessment of the antigenic and immunogenic activity of the vaccine at an early period after immunization (the term of observation not exceeding 3 months). On the basis of the complex comparison of the indices characterizing the reactogenicity and the antigenic and immunogenic activity of 4 tested doses of brucellosis chemical vaccine a dose of 1 mg was chosen as the optimum vaccination dose.