4-1BB and OX40 stimulation enhance CD8 and CD4 T-cell responses to a DNA prime, poxvirus boost vaccine

4-1BB (CD137) is a tumour necrosis factor receptor (TNFR) family member, expressed primarily on CD8 T cells after activation. Signalling through 4-1BB has been reported to enhance CD8 T-cell expansion and to protect activated CD8 T cells from death, resulting in an enlarged memory population. Although stimulating 4-1BB has been shown to significantly improve the immune response to weak immunogens such as tumours, little is known about its effect on the CD8 T-cell response to a powerful viral vector such as vaccinia. To test 4-1BB's ability to improve the murine CD8 T cell response to a DNA prime, poxvirus boost vaccine, similar to those used for human immunodeficiency virus and simian immunodeficiency virus vaccines, we administered 4-1BB agonist antibody at the time of the poxvirus boost. 4-1BB stimulation increased the number of functional memory CD8 T cells by two- to fourfold. However, we saw a similar enhancement at the peak of the response and in the memory phase, thus we found no evidence in the context of virus infection that 4-1BB stimulation could increase the percentage of CD8 T cells that survive the acute activation phase to become memory cells. OX40 (CD134) is an analogous TNFR family member expressed primarily on activated CD4 T cells. OX40 stimulation increased the number of antigen-specific CD4 T cells approximately threefold. Stimulating both 4-1BB and OX40 enhanced the CD8 T-cell response more than 4-1BB alone. Thus stimulating these receptors can improve the response to a powerful virus vector, and may be useful in vaccine development.     

Blood levels of TT virus following immune stimulation with influenza or hepatitis B vaccine

Torque Teno virus (TTV) has been demonstrated to be present persistently in the blood of healthy individuals without evidence that it causes any disease process. The levels of TTV vary in patients co-infected with other viruses and there has been considerable speculation as to whether TTV contributes to pathogenesis by other viruses or if the varying levels might be related to immune activation in the host. In the present study, the load of TTV was examined in plasma and peripheral blood mononuclear cells (PBMCs) following immunization of subjects with either influenza (a recall antigen) or hepatitis B virus (HBV) (a new antigenic exposure). The results overall did not indicate a significant change in TTV titers over a 90 day observation period; however, when TTV genogroup was taken into consideration there was an increase in viral load in plasma at some time points for subjects persistently infected with genogroup 3. While this was observed in both influenza and HBV immunized subjects, the effect was more profound in HBV vaccination. Thus, it appears that exposure to a new antigen rather than a recall antigen may stimulate TTV replication more effectively. The data further suggest that investigating the interactions between TTV and its host might require to examine specifically each TTV genogroup separately in order to determine if certain TTV types have any role in disease pathogenesis.     

Different immune responses after intradermal and intramuscular administration of vaccine against tick-borne encephalitis virus

A single multisite intradermal (ID) administration of the same dose used for regular intramuscular (IM) immunisation with vaccine against tick-borne encephalitis virus (TBEV) resulted in seroconversion of all vaccinees within three weeks: with the regular IM schedule, two vaccinations were necessary for all vaccinees to seroconvert. After the first ID vaccination, antibodies of the IgM class against TBEV (anti-TBEV-IgM) were observed in all vaccinees; after the first IM vaccination, only three out of nine vaccinees showed an IgM response. The geometric mean titer (GMT) of anti-TBEV-IgM in seropositives was 5–20-fold higher in the ID group and similar to that after natural infection. The GMT of antibodies of the IgG class against TBEV (anti-TBEV-IgG) was also higher in the ID group but with a less marked difference. Hemagglutination-inhibiting (HI) antibodies appeared earlier and persisted longer after one or two ID injections; after a third vaccination, HI antibody levels were similar in both groups. Side effects after ID vaccination were limited to local reactions. These results indicate that follow-up injections may be omitted or at least reduced after ID administration of the vaccine dose usually used for IM vaccination schedules. However, additional studies in larger groups of vaccinees are necessary before ID vaccination can be recommended for general use.     

Booster shot of inactivated SARS-CoV-2 vaccine induces potent immune responses in people living with HIV

This study aimed to investigate the immunogenicity to SARS-CoV-2 and evasive subvariants BA.4/5 in people living with HIV (PLWH) following a third booster shot of inactivated SARS-CoV-2 vaccine. We conducted a cross-sectional study in 318 PLWH and 241 healthy controls (HC) using SARS-CoV-2 immunoassays. Vaccine-induced immunological responses were compared before and after the third dose. Serum levels of IgG anti-RBD and inhibition rate of NAb were significantly elevated at the “post-third dose” sampling time compared with the pre-third dose in PLWH, but were relatively decreased in contrast with those of HCs. Induced humoral and cellular responses attenuated over time after triple-dose vaccination. The neutralizing capacity against BA.4/5 was also intensified but remained below the positive inhibition threshold. Seropositivity of SARS-CoV-2-specific antibodies in PLWH was prominently lower than that in HC. We also identified age, CD4 cell counts, time after the last vaccination, and WHO staging type of PLWH as independent factors associated with the seropositivity of antibodies. PLWH receiving booster shot of inactivated vaccines generate higher antibody responses than the second dose, but lower than that in HCs. Decreased anti-BA.4/5 responses than that of WT impede the protective effect of the third dose on Omicron prevalence.     

Inflammatory responses to influenza vaccination at the extremes of age

Age affects the immune response to vaccination, with individuals at the extremes of age responding poorly. The initial inflammatory response to antigenic materials shapes the subsequent adaptive response and so understanding is required about the effect of age on the profile of acute inflammatory mediators. In this study we measured the local and systemic inflammatory response after influenza vaccination or infection in neonatal, young adult and aged mice. Mice were immunized intramuscularly with inactivated influenza vaccine with and without the adjuvant MF59 and then challenged with H1N1 influenza. Age was the major factor affecting the inflammatory profile after vaccination: neonatal mice had more interleukin‐1α (IL‐1α), C‐reactive protein (CRP) and granulocyte–macrophage colony‐stimulating factor (GMCSF), young adults more tumour necrosis factor‐α (TNF), and elderly mice more interleukin‐1 receptor antagonist (IL‐1RA), IL‐2RA and interferon‐γ‐induced protein 10 (IP10). Notably the addition of MF59 induced IL‐5, granulocyte colony‐stimulating factor (G‐CSF), Keratinocyte Chemotractant (KC) and monocyte chemoattractant protein 1 (MCP1) in all ages of animals and levels of these cytokines correlated with antibody responses. Age also had an impact on the efficacy of vaccination: neonatal and young adult mice were protected against challenge, but aged mice were not. There were striking differences in the localization of the cytokine response depending on the route of exposure: vaccination led to a high serum response whereas intranasal infection led to a low serum response but a high lung response. In conclusion, we demonstrate that age affects the inflammatory response to both influenza vaccination and infection. These age‐induced differences need to be considered when developing vaccination strategies for different age groups.     

Cell mediated immune responses against human prion protein

Vaccination approaches that may provide protection against the abnormal form of prion protein (PrPSc) have recently focused on the ability of antibodies to prevent PrPSc propagation. Progress has been hampered due to the difficulty in generating antibody responses in wild type mice, which is believed to be a consequence of T cell tolerance to the normal form of prion protein (PrPC). The problem of tolerance can be avoided using transgenic mice unable to express PrPC. This study examines active PrP specific T cell responses that can be produced in PrP null (PrP 0/0) mice using simple peptide vaccination procedures. Spleenocytes recovered from vaccinated PrP 0/0 mice were tested in vitro for their specificity with T cell recognition demonstrated through a proliferative response to the peptide. Analysis of mRNA also indicates the stimulation of a heterogenous population of T cells with an increase in cytokines and cytotoxicity associated mRNA. Responsive T cells were expanded using a T cell cloning procedure and demonstrated an ability to recognize the mature human prion protein. These clones may potentially be used to negate the problem of T cell tolerance in wild type mice.     

CpG ODN增强乙肝疫苗在老年小鼠中的免疫应答

目的：探讨CpG ODN对老年小鼠的体液和细胞免疫应答的增强作用。方法：选用老年C57BL／6小鼠，将乙肝疫苗和10μg、20μg CpG ODN同时或单独肌注到小鼠体内，两周后以同样剂量加强免疫一次，再过3周后摘除眼球取血，用EILSA方法检测抗HBs16；抗体和IL-12；无菌取脾脏作HE染色，观察脾脏淋巴细胞变化。结果：10μg和20μg CpG ODN与疫苗同时注射组产生的抗体绝对量分别是单独注射疫苗组的3倍和4倍；产生的IL-12水平较对照组有明显升高，且20μg比10μCpG组产生的IL-12水平更高。光镜下各组的脾脏淋巴细胞的变化如下：正常老年鼠组脾脏淋巴细胞较正常青年鼠组明显稀少；老年鼠 10μgCpG组脾脏淋巴细胞较正常老年鼠组有了明显增加，且细胞核也明显增大；20μgCpG组增加的更加明显。结论：CpG ODN能增强乙肝疫苗在老年小鼠中的体液和细胞免疫应答。     

Acquired immune responses to the seasonal trivalent influenza vaccination in COPD

Epidemiological data suggest that influenza vaccination protects against all-cause mortality in chronic obstructive pulmonary disease (COPD) patients. However, recent work has suggested there is a defect in the ability of some COPD patients to mount an adequate humoral response to influenza vaccination. The aim of our study was to investigate humoral and cell-mediated vaccine responses to the seasonal trivalent influenza vaccination (TIV) in COPD subjects and healthy controls. Forty-seven subjects were enrolled into the study; 23 COPD patients, 13 age-matched healthy controls (HC ≥ 50) and 11 young healthy control subjects (YC ≤ 40). Serum and peripheral blood mononuclear cells (PBMC) were isolated pre-TIV vaccination and at days 7 and 28 and 6 months post-vaccine for haemagglutinin inhibition (HAI) titre, antigen-specific T cell and antibody-secreting cell analysis. The kinetics of the vaccine response were similar between YC, HC and COPD patients and there was no significant difference in antibody titres between these groups at 28 days post-vaccine. As we observed no disease-dependent differences in either humoral or cellular responses, we investigated if there was any association of these measures with age. H1N1 (r = −0·4253, P = 0·0036) and influenza B (r = −0·344, P = 0·0192) antibody titre at 28 days negatively correlated with age, as did H1N1-specific CD4⁺ T helper cells (r = −0·4276, P = 0·0034). These results suggest that age is the primary determinant of response to trivalent vaccine and that COPD is not a driver of deficient responses per se. These data support the continued use of the yearly trivalent vaccine as an adjunct to COPD disease management.     

Immunodominance in CD4 T-cell responses: implications for immune responses to influenza virus and for vaccine design

CD4 T cells play a primary role in regulating immune responses to pathogenic organisms and to vaccines. Antigen-specific CD4 T cells provide cognate help to B cells, a requisite event for immunoglobulin switch and affinity maturation of B cells that produce neutralizing antibodies and also provide help to cytotoxic CD8 T cells, critical for their expansion and persistence as memory cells. Finally, CD4 T cells may participate directly in pathogen clearance via cell-mediated cytotoxicity or through production of cytokines. Understanding the role of CD4 T-cell immunity to viruses and other pathogens, as well as evaluation of the efficacy of vaccines, requires insight into the specificity of CD4 T cells. This review focuses on the events within antigen-presenting cells that focus CD4 T cells toward a limited number of peptide antigens within the pathogen or vaccine. The molecular events are discussed in light of the special challenges that the influenza virus poses, owing to the high degree of genetic variability, unpredictable pathogenicity and the repeated encounters that human populations face with this highly infectious pathogenic organism.     

Polyvalent vaccine approaches to combat HIV-1 diversity

A key unresolved challenge for developing an effective HIV-1 vaccine is the discovery of strategies to elicit immune responses that are able to cross-protect against a significant fraction of the diverse viruses that are circulating worldwide. Here, we summarize some of the immunological implications of HIV-1 diversity, and outline the rationale behind several polyvalent vaccine design strategies that are currently under evaluation. Vaccine-elicited T-cell responses, which contribute to the control of HIV-1 in natural infections, are currently being considered in both prevention and treatment settings. Approaches now in preclinical and human trials include full proteins in novel vectors, concatenated conserved protein regions, and polyvalent strategies that improve coverage of epitope diversity and enhance the cross-reactivity of responses. While many barriers to vaccine induction of broadly neutralizing antibody (bNAb) responses remain, epitope diversification has emerged as both a challenge and an opportunity. Recent longitudinal studies have traced the emergence of bNAbs in HIV-1 infection, inspiring novel approaches to recapitulate and accelerate the events that give rise to potent bNAb in vivo. In this review, we have selected two such lineage-based design strategies to illustrate how such in-depth analysis can offer conceptual improvements that may bring us closer to an effective vaccine.     

The adhesion receptor CD155 determines the magnitude of humoral immune responses against orally ingested antigens

CD155, originally known as the cellular receptor for poliovirus, is the founding member of a subfamily of immunoglobulin-like adhesion receptors. Apart from its function in establishing adherens junctions between contacting epithelial cells, the engagement of CD155 with two recently identified ligands, CD226 and CD96, mediates immunologically relevant processes such as NK cell-driven killing of tumor cells in humans. Here we report on the generation and immunological analysis of mice constitutively deficient of CD155. Moreover, the expression profile of CD155 on hematopoietic cells has been determined using newly established antibodies. CD155-deficient mice develop normally without displaying an overt phenotype. However, the animals are distinguished by distinct deficits in the development of a regular humoral immune response. Whereas systemic challenges revealed no differences, orally administered antigen evoked less efficient IgG and IgA antibody responses despite of normal IgM titers when compared to wild-type mice. Therefore, CD155 may assist in an efficient humoral immune response generated within the intestinal immune system.     

Effect of age on serum immunoglobulin G subclass antibody responses to inactivated influenza virus vaccine

We previously reported an age-associated impairment of serum immunoglobulin G (IgG) antibody responses to inactivated influenza virus vaccine. The present study extends these observations by examining the IgG subclass distribution of vaccine responses measured by enzyme linked immunosorbent assay in healthy adults aged <40 (young), 40–64 (middle-aged), and ?65 (elderly) years. Serological responses in all age groups showed antibodies that were predominantly IgG1 and secondarily IgGS. Influenza antigen-specific IgG4 titers did not change following vaccination, and antibodies of the IgG2 subclass were not detected in any serum specimens. Aging was associated with a significant impairment of IgG1, but not of IgGS, antibody production. Relative differences in the magnitude and frequency of response between IgG1 and IgGS subclasses, which were present in young and middle-aged adults (viz., IgG1 > IgGS), were less apparent in the elderly. This observation was confirmed in a second analysis of IgG subclass-specific responses in a separate cohort of elderly vaccinees. These results suggest that the age-related impairment of humoral responses to inactivated influenza virus vaccine is primarily accounted for by differences in IgG1 antibody production, and that IgGS antibodies make up a larger proportion of the overall serologic response in the elderly than they do in younger persons. © 1994 Wiley-Liss, Inc.     

Prevalence of antibody to current influenza virus strains in adolescents

During the Spring of 1986, 118 pupils aged 15-18 years were surveyed for the presence of humoral antibodies to five influenza strains. Prevalence of humoral immunity (HI) antibodies and immunity was found to be related to the year of the strain's emergence and to length of circulation time in the community. A high percentage of the adolescents were not immune to one or more of the tested strains. More than 40% of the studied group were not immune to the old A strains A/Philipines 2/82 (H3N2) and A/Chile 1/83 (H1N1), nearly 70% were not immune to the two B strains (B/USSR 100/83 and B/Ann Arbor 1/86), and almost the entire group (96%) was unprotected against the recent strain A/Singapore 6/86. Only one pupil was immune to all five strains; 35.6%, 22.2%, 17.8%, and 9.2% were immune to one, two, three, or four of the strains, respectively; and 14.4% were not immune to even one strain.     

The impact of timing of maternal influenza immunization on infant antibody levels at birth

Pregnant women and infants are at an increased risk of severe disease after influenza infection. Maternal immunization is a potent tool to protect both these at-risk groups. While the primary aim of maternal influenza vaccination is to protect the mother, a secondary benefit is the transfer of protective antibodies to the infant. A recent study using the tetanus, diphtheria and acellular pertussis (Tdap) vaccine indicated that children born to mothers immunized in the second trimester of pregnancy had the highest antibody titres compared to children immunized in the third trimester. The aim of the current study was to investigate how the timing of maternal influenza immunization impacts infant antibody levels at birth. Antibody titres were assessed in maternal and cord blood samples by both immunoglobulin (Ig)G-binding enzyme-linked immunosorbent assay (ELISA) and haemagglutination inhibition assay (HAI). Antibody titres to the H1N1 component were significantly higher in infants born to mothers vaccinated in either the second or third trimesters than infants born to unvaccinated mothers. HAI levels in the infant were significantly lower when maternal immunization was performed less than 4 weeks before birth. These studies confirm that immunization during pregnancy increases the antibody titre in infants. Importantly, antibody levels in cord blood were significantly higher when the mother was vaccinated in either trimesters 2 or 3, although titres were significantly lower if the mother was immunized less than 4 weeks before birth. Based on these data, seasonal influenza vaccination should continue to be given in pregnancy as soon as it becomes available.     

A dual purpose universal influenza vaccine candidate confers protective immunity against anthrax

Preventive influenza vaccines must be reformulated annually because of antigen shift and drift of circulating influenza viral strains. However, seasonal vaccines do not always match the circulating strains, and there is the ever‐present threat that avian influenza viruses may adapt to humans. Hence, a universal influenza vaccine is needed to provide protective immunity against a broad range of influenza viruses. We designed an influenza antigen consisting of three tandem M2e repeats plus HA2, in combination with a detoxified anthrax oedema toxin delivery system (EFn plus PA) to enhance immune responses. The EFn‐3×M2e‐HA2 plus PA vaccine formulation elicited robust, antigen‐specific, IgG responses; and was protective against heterologous influenza viral challenge when intranasally delivered to mice three times. Moreover, use of the detoxified anthrax toxin system as an adjuvant had the additional benefit of generating protective immunity against anthrax. Hence, this novel vaccine strategy could potentially address two major emerging public health and biodefence threats.     

CD40/CD40L dyad in the inflammatory and immune responses in the central nervous system

CD40 and its cognate ligand （CD40L） are a pair of regulators of pro-inflammatory and immune responses. In the central nervous system （CNS）, CD40 is expressed on a variety of cells, including vascular endothelial cells, smooth muscle cells, astrocytes and microglia （the brain macrophages, being the most sensitive cell type to respond to CD40 ligand）. Interaction between CD40 on microglia and CD40L presented by infiltrating T lymphocytes and other resident CNS cells triggers a series of intracellular signaling events that promote the production of a wide array of cytokines, chemokines and neurotoxins. Thus, both molecules serve as amplifiers of pro-inflammatory and immune responses in the CNS and constitute important molecular targets for therapeutic intervention of diseases.Cellular ＆ Molecular Immunology. 2006;3（3）：163-169.     

Properties of mouse CD40: Cellular distribution of CD40 and B cell activation by monoclonal anti-mouse CD40 antibodies

We describe here the derivation of a rat monoclonal antibody (mAb) against mouse CD40 (designated 3/23), which stains 45–50% of spleen cells of adult mice, approximately 90% of which are B cells. Interestingly, some 5–10% of both CD4⁺ and CD8⁺ T cells in the spleens of (some, but not all) adult, unimmunized mice are also CD40⁺, whereas CD40⁺ cells were not detectable in the thymus, even following collagenase digestion. Some 35–40% of lymphoid cells in the bone marrow of adult mice are CD40⁺ and virtually all of these are B220⁺, and hence of the B cell lineage: triple-color flow cytometry showed that CD40 is expressed at low levels on some 30% of pre-B cells, at intermediate levels on 80% of immature B cells and on essentially all mature B cells in the bone marrow. These results, therefore, suggest that in the mouse CD40 is expressed relatively late during the process of B cell differentiation. The mAb induced marked up-regulation of major histocompatibility complex class II molecules, CD23 and B7.2 antigens on mature B cells. It also stimulated modest levels of DNA synthesis in mature B cells by itself: this was markedly enhanced by suboptimal concentrations of mitogenic (but not non-mitogenic) anti-μ and anti-δ mAb, and moderately enhanced by co-stimulation with interleukin-4. Hyper-cross-linking of CD40 (using biotinylated mAb and avidin) also enhanced the proliferative response to anti-CD40.     

The delivery site of a monovalent influenza vaccine within the respiratory tract impacts on the immune response

Pulmonary vaccination is a promising immunization route. However, there still remains a crucial need to characterize the different parameters affecting the efficacy of inhaled vaccination. This study aimed at assessing the impact of antigen distribution within the respiratory tract on the immune response to a monovalent A/Panama/2007/99 H3N2 influenza split virus vaccine administered to BALB/c mice. Varying the administration technique allowed the targeting of the vaccine to different sites of the mouse respiratory tract, i.e. the nasal cavity, the upper or central airways, or the deep lung. This targeting was verified by using ovalbumin as a tracer compound. The immune responses generated following influenza vaccine administration to the different respiratory tract sites were compared to each other and to those elicited by intramuscular and peroral intragastric immunization. Delivery of the vaccine to the different respiratory regions generated systemic, local and cellular virus-specific immune responses, which increased with the depth of vaccine deposition, culminating in deep-lung vaccination. The latter induced virus-specific serum immunoglobulin G and neutralizing antibody titres as elevated as intramuscular vaccination, whereas the production of mucosal secretory immunoglobulin A was significantly superior in deep-lung-vaccinated animals. The analysis of cytokines secreted by mononuclear cells during an in vitro recall response indicated that deep-lung vaccination induced a local shift of the cellular immune response towards a T helper type 1 phenotype as compared to intramuscular vaccination. In conclusion, antigen distribution within the respiratory tract has a major effect on the immune response, with the deep lung as the best target for inhaled influenza vaccination.