Transcriptional signatures of fully protected participants
The vaccine immunogenicity assessment showed that the group of fully protected individuals was the smallest. Our main objective was to understand the transcriptomic profiles after vaccination of this particular group and analyze the transcriptional signatures that played a role in their rapid immune response and durable seroprotection. Transcriptomic profiling was performed twice, prior vaccination at day 0 and post vaccination at day 7. Through differential expression analysis, we identified 1849 differentially expressed transcripts between day 7 and day 0 in the group of fully protected participants, of which 708 transcripts were up-regulated and 1141 transcripts were down-regulated. In contrast, 1430, 857, 784 transcripts were differentially expressed in the groups of partial, weak and no protection respectively. Only 316 transcripts were overlapped between the four groups and 1057 transcripts were expressed only in the group of fully protected participants (Supplementary Tables 1).
An unsupervised hierarchical cluster analysis was performed on 1849 transcripts that were differentially expressed in the fully protected group and revealed two distinct clusters, which reflected significant changes in gene expression levels before and after vaccination at day 7 (Fig. 2A). This was further supported by a principal component analysis on the same set of transcripts, comparing all the participants, and revealed a distinct cluster that separated the fully protected group from the other groups (Fig. 2B).
Gene ontology (GO) enrichment of molecular processes (Supplementary Table 2) provided a straightforward interpretation of the differently expressed transcripts in the fully protected group and highlighted the main biological processes and molecular pathways involved in the influenza vaccine response mechanism (Fig. 3). The process of B cell activation was enriched (p-value = 1.7e-08), this process is pivotal to the vaccine response and involves sophisticated pathways and signalling cascades upon binding to antigens derived from the inactivated influenza virus strains [19–21]. Several biological processes were enriched indicating the activation of B cells due to the recognition of antigens and the transmission of activation signals through the B-cell receptor: B cell receptor signalling pathway (p-value = 9.3e-12), phagocytosis recognition (p-value = 1.2e-11), antigen receptor-mediated signalling pathway (p-value = 3.3e-07), and immune response-activating cell surface receptor signalling pathway (p-value = 1.5e-05). These processes emphasize the need of promptly reacting to an antigenic stimulus, as well as the availability of a diverse repertoire of naïve B cells in order to achieve a successful activation of B cells. The significant differentially expressed transcripts that contributed to the enrichment of these processes included: FCRL1 and CD40. The expression of FCRL1 attains its highest levels in naive B cells, and then decreases once B cells become activated and start forming germinal centres [22]. On the other hand, the expression of CD40 indicates possible interaction with helper T cells that influence naive B cell development and activation via CD40 signalling [23].
The B-cell receptor dependent signal stimulated by an antigen also triggers the development of B lymphoblasts, which divide and differentiate into short-lived plasmablasts that secrete antibodies [24]. This initial extrafollicular response produces early protective antibodies of slightly lower affinity towards the inactivated influenza virus strains and with shorter life span. Furthermore, B cells possess the indispensable ability to phagocyte and process antigens to present antigenic peptides on B cell surface via major histocompatibility complex (MHC) class II molecules. This serves as a communication facility between activated B cells and follicular helper T cells (TFH) having the same antigen-specificity and residing near the B cell follicles [25–26]. Once TFH cells come into contact with B cells that display identical linked antigen epitopes on their MHC class II molecules, TFH cells start to help by expressing their CD40 ligand and secreting various cytokines that promotes the survival and proliferation of B cells. Moreover, under the influence and support of TFH cells, germinal centres begin to form and activated follicular B cells begin to undergo affinity maturation to effectively target specific viral epitopes [27–32]. The germinal centres form several days after antigen encounter as temporary structures in the centre of the B cell follicles and characterized by intense cellular activity involving cell division and cell death. This region is surrounded by a network of follicular dendritic cells (FDCs) [33], a group of activated and resting B cells, and antigen specific TFH cells. The germinal centre itself is comprised of two primary areas: the light zone and the dark zone. Within the dark zone, activated B cells undergo proliferation and somatic hypermutation (SHM) to adapt their specific immunoglobulin variable regions, which make up the antigen-binding sites of their B cell receptor (BCR), in order to increase affinity and better align with epitopes present in influenza virus proteins, which include the surface hemagglutinin (HA) glycoprotein, the primary target of the vaccine.
B cells with higher-affinity BCRs move to the light zone and attempt to capture antigens trapped on FDCs for further processing and presenting on their MHC class II molecules. Alternatively, B cells with lower-affinity BCRs are unable to effectively capture and present antigens. Consequently, these B cells ultimately undergo apoptosis and die due to lack of support from TFH. On the other hand, successfully proliferating B cells undergo repeated cycles of entry to the dark zone for continuous somatic hypermutations and affinity selection. The germinal centre formation and reactions enriched the biological process termed adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains (p-value = 1.7e-4). The significant differentially expressed transcripts that contributed to the enrichment of this process included: TLR4, IL4, and BCL6. The expression of TLR4 modulates FDC activation and maturation, and plays a role in preventing GC B cell apoptosis [34]. On the other hand, the expression of BCL6 is regulated by IL4 cytokine, while BCL6 acts as a critical mediator of the magnitude and duration of the GC responses [35].
Ultimately B cells exit the germinal centre either as long-lived plasma cells (LLPCs) or memory B cells (MBCs) [36]. The former, LLPCs migrate to the bone marrow and compete for dedicated survival niches that enable them to sustain antibody secretion for a prolonged duration [37–42]. Meanwhile, MBCs retain their B cell characteristics in anticipation of encountering the same antigen, and are programmed to rapidly differentiate into antibody-secreting cells (ASCs) of high affinity [43–44]. The generation of these two B cell lineages and the production of antibodies are the expected outcomes of successful vaccination, which led to the enrichment of two significant biological processes that indicate the production of antibodies through biosynthesis after exposure to a stimulus: humoral immune response mediated by circulating immunoglobulin (p-value = 4.7e-14) and immunoglobulin production (p-value = 6.9e-9). The significant differentially expressed transcripts that contributed to the enrichment of these processes included: MZB1 and XBP1. Both transcripts code for multifunctional proteins that are involved in the differentiation of B cells into plasma cell and the proper adaptation and functioning of antibody secreting cells. These two transcripts are among the list of potential genes that are found contributing to the ideal vaccine response, further explanation and details are provided in the following section.
Genes with Significant Variations in log2-fold Change between the Fully Protected Group and the Non-fully Protected Groups
We analyzed the transcriptional signature of the fully protected group and compared each significant transcript's log2-fold change with those of the three groups that did not achieve full protection – namely, the partially protected, weakly protected, and unprotected groups. Through analysis of variance (Supplementary Table 3), we identified a list of 16 genes that showed significant pair-wise differences in their log2-fold change means between the fully protected group and the other three groups, indicating their potential influence on the effectiveness of the vaccine response (Fig. 4). The identified 16 genes are CD38, SDC1, MZB1, TNFRSF17, TNFRSF13B, POU2AF1, PAX5, IRF4, TXNDC5, TXNDC11, HSP90B1, FKBP11, PDIA5, MYDGF, PRDX4 and XBP1.
Considering the significant variations in the log2-fold change observed among the groups, we attempted to investigate the known functions of each gene to gain insight and comprehend the potential impact of these genes on the ideal vaccine response.
1) CD38 was up-regulated within the fully protected group, with an average log2-fold change of 2.95. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 1.64, 1.36, and 1.15 respectively. CD38, also referred to as CADPR1, is a multifunctional protein expressed on the surface of B cells in healthy individuals. It acts as both a receptor and a multifunctional enzyme, one of its key roles is to catalyze the synthesis and hydrolysis of a general calcium messenger molecule cyclic ADP-ribose (cADPR) [45]. Recent research has revealed that CD38 has a strong connection with CD19 in inactive B cells, as well as with the IgM B cell receptor when it is in an engaged state, suggesting a modulatory effect on B cell activation upon antigen recognition by regulating CD19 [46]. Furthermore, researchers used CD19 and CD38, and CD138 to classify different plasma cell subsets in the bone marrow of human subjects and their findings revealed that the CD19−CD38++CD138+ subset was morphologically distinct and exclusively contained PCs that targeted viral antigens which the subjects had not encountered for over four decades [47], consequently, elevated levels of CD38 expression may indicate the effective production of LLPCs.
2) SDC1 was up-regulated within the fully protected group, with an average log2-fold change of 1.46. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 0.79, 0.73, and 0.48 respectively. SDC1, also referred to as CD138 antigen, encodes a heparin-sulfate glycoprotein. SDC1 is a member of the syndecan proteoglycan family that mediates cell signalling, cell binding and cell migration. CD138 serves as a cell surface marker for normal B cells and is expressed at varying levels throughout different stages of B cell differentiation [48]. Higher expression of CD138 indicates the presence of LLPC. Notably, the expression of CD138 on ASCs leads to increased levels of heparan sulfate, known for its ability to bind pro-survival cytokines like IL-6 and APRIL and protect ASCs from apoptosis and promote longevity [49].
3) MZB1 was up-regulated and exhibited a remarkable increase in expression level within the fully protected group, with an average log2-fold change of 3.66. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 2.36, 2.04, and 1.7 respectively. MZB1, also referred to as pERp1, encodes the marginal zone B and B1 cell specific protein. It is found within the endoplasmic reticulum (ER) as a component of the BiP chaperone complex. MZB1 belongs to the CNPY family of ER resident saposin-like proteins and it has saposin-fold with unique sequence extensions not present in other saposin proteins [50]. During the process of the B cell to plasma cell differentiation, MZB1 is significantly up-regulated and analyses demonstrated that MZB1 is an unusual type of resident ER protein that specifically assists immunoglobulin biosynthesis. Knowing that, plasma cells have the ability to produce and release huge amounts of immunoglobulin molecules that undergo assembly and oxidative folding within the ER [51]. Other studies revealed that deletion of MZB1 adversely affects humoral immune responses and the secretion of antibodies in plasma cells that naturally undergo ER stress [52]. In addition, retention of ASCs in the bone marrow and their maturation into plasma cells require the involvement of a cell surface molecule known as very late antigen 4 (VLA4). Interestingly, ASCs deficient in the co-chaperone MZB1, which is essential for VLA4 activation, showed impaired ability to migrate and home in the bone marrow [53].
4) TNFRSF17 was up-regulated within the fully protected group, with an average log2-fold change of 3.01. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 1.63, 1.3, and 1.06 respectively. TNFRSF17, also referred to as BCMA or TNFRSF13A, encodes the tumor necrosis factor (TNF) Receptor Superfamily Member 17 protein. It is a non glycosylated integral membrane protein that is preferentially expressed in mature B lymphocytes. TNFRSF17 interacts with TNF receptor-associated factor TRAF1, TRAF2, and TRAF3, leading to the activation of nuclear factor-kappa B (NF-κB), elk-1, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase [54]. B-cell activating antigen (BCMA), transmembrane activator and CAML interactor (TACI) and B-cell activating factor receptor (BAFFR) serve as receptors for B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL), establishing a complex network that plays a crucial role in the progression of humoral immunity. More specifically, the functional activity of the BCMA receptor aids in promoting the survival of LLPCs [55–58]. The investigation into the genetic knockout of TNFRSF17 yielded noteworthy findings, a substantial reduction of ASCs in the bone marrow when compared to wild-type controls, occurring 6–8 weeks after immunization. Nevertheless, germinal centre responses and early antigen-specific serum IgM and IgG levels remained within normal ranges, indicating that the primary impact of losing BCMA affected the LLPCs [58].
5) TNFRSF13B was up-regulated within the fully protected group, with an average log2-fold change of 2.22. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 1.17, 1.07, and 1.05 respectively. TNFRSF13B, also referred to as TACI, encodes a lymphocyte-specific member of the TNF receptor superfamily. The TNF superfamily ligands BAFF and APRIL, along with their three receptors BAFFR, BCMA, and TACI, play significant roles in the immunological functions of the B cell arm of the immune system. BAFF-R specifically targets BAFF, while BCMA has a greater affinity for APRIL compared to BAFF. On the other hand, TACI is capable of binding both ligands with equal effectiveness. TACI facilitates NF-κB responses and triggers the process of immunoglobulin IgG and IgA class-switch recombination in B cells. In humans, TACI deficiency was found to manifest as an antibody deficiency syndrome [59–63].
6) POU2AF1 was up-regulated within the fully protected group, with an average log2-fold change of 0.88. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 0.69, 0.18, and 0.04 respectively. POU2AF1, also referred to as B cell-specific coactivator (OCA-B) or OBF-1, encodes octamer-binding factor protein. OCA-B polypeptide is the primary factor that activates immunoglobulin (Ig) promoters in B cells, working in conjunction with OCT-1 and OCT-2 binding proteins; it forms a binding complex that specifically targets octamer sites found in both promoters and enhancers. Its main role is to initiate the transcription process for Ig genes in B cells [64–66]. Furthermore, the transcriptional activator OCT-2, along with its cofactor OBF-1, serves as key regulatory factors for IL6 expression, driving the differentiation of activated CD4 + T cells into TFH cells. Therefore, OBF1 plays a role in the response of B cells to thymus-dependent antigens, being essential for the formation of germinal centres that are fundamental to the generation of high-affinity antibody-secreting cells [67–69].
7) PAX5 was up-regulated within the fully protected group, with an average log2-fold change of 0.95. In contrast, it was down-regulated within the partially, weakly, and non-protected groups, with average log2-fold changes of -0.2, -0.05, and − 0.25 respectively. PAX5, also referred to as B-Cell lineage specific activator protein (BSAP), encodes a member of the paired box (PAX) family of transcription factors. PAX5 is a unique transcription factor that safeguards the B-lymphocyte lineage commitment and performs a dual role by activating B cell-specific genes and simultaneously repressing B cell-lineage unspecific genes [70]. The pro-B cell stage signifies a B cell lineage commitment phase, wherein the rearrangement of heavy-chain genes takes place. Approximately 23% of all expression alterations observed during the transition from common lymphoid progenitors to committed pro-B cells can be attributed to PAX5 regulated genes, which identifies PAX5 as an essential regulator of B cell developmental transition [71]. The targets of PAX5 activation include immune receptors, such as CD19 and CD21, as well as transcription factors interferon regulators, such as IRF4, IRF8, and BACH2 [72]. The PAX5 repressed genes control a wide range of biological functions, including cell communication, adhesion, migration, nuclear processes, and cellular metabolism as part of the process of B cell commitment [73]. For instance, PAX5 repression of the cohesin-release factor WAPL in pro-B cells results in alterations to the chromosomal architecture which facilitates the generation of a diverse antibody repertoire [74]. Studies also revealed that PAX5 plays a role in proliferation and immunoglobulin isotype switching in germinal centre B cells [75].
8) IRF4 was up-regulated within the fully protected group, with an average log2-fold change of 0.8. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 0.26, 0.14, and 0.12 respectively. IRF4 encodes a transcription factor belongs to o the IRF (interferon regulatory factor) family of transcription factors characterized by a specific DNA-binding domain and the ability to bind to regulatory elements in promoters of interferon-inducible genes [76]. IRF4 is required for the generation of germinal centre B cells by inducing the expression of key germinal centre genes including BCL6 and AICDA. IRF4 also induces BLIMP1 which handles the transition from a germinal centre B cell gene expression program to that of a plasma cell. This multifunctional nature of IRF4 implies its involvement in a multifaceted regulatory network, wherein its expression levels plays an additional role, lower IRF4 expression levels appear to facilitate the progression of the germinal centre pathway and higher expression levels promote the differentiation of plasma calls [77]. Investigating the involvement of IRF4 in post germinal centre B cell development revealed that IRF4 plays an important role in the differentiation of plasma cells and the process of class switch recombination (CSR). The conditional deletion of IRF4 in germinal centre B cells lacked post–germinal centre plasma cells and inability to differentiate memory B cells into plasma cells, which highlights the significance of IRF4 as a pivotal transcriptional regulator in the development of plasma cells [78].
9) TXNDC5 was up-regulated and exhibited a remarkable increase in expression level within the fully protected group, with an average log2-fold change of 4.79. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 3.11, 2.74, and 2.43 respectively. TXNDC5, also referred to as PDIA15 or ERp46, encodes the thioredoxin domain-containing protein 5 and a member of the protein disulfide isomerase (PDI) family. It plays a role in the formation and rearrangement of disulfide bonds for proper protein folding. In addition, TXNDC5 functions as a molecular chaperone, regulating the synthesis of abnormal proteins and maintaining cellular homeostasis. TXNDC5 possesses various biological functions, including anti-oxidation, promoting angiogenesis, cellular inflammation, and energy metabolism [79–80].
10) TXNDC11 was up-regulated within the fully protected group, with an average log2-fold change of 1.24. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 0.7, 0.51, and 0.4 respectively. TXNDC11, also referred to as EFP1, encodes the thioredoxin domain-containing protein 11. TXNDC11 is specifically induced by ER stress and regulated by the IRE1-XBP1 pathway. This pathway is a major component of the unfolded protein response (UPR) signalling pathway, which plays a significant role in maintaining cellular homeostasis [81].
11) HSP90B1 was up-regulated within the fully protected group, with an average log2-fold change of 1.47. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 0.71, 0.67, and 0.44 respectively. HSP90B1, also referred to as GRP94, encodes heat shock protein 90 beta family member 1. It is an important ER molecular chaperone that plays a role in the UPR pathway and enhances the functioning of B cells by chaperoning TLRs and integrins. The chaperone function of the HSP90B1 gene is of great significance in protein physiology, as well as in the processing and transportation of secreted proteins [82].
12) FKBP11 was up-regulated within the fully protected group, with an average log2-fold change of 1.41. In contrast, the partially, weakly, and non-protected groups demonstrated lower average log2-fold changes of 0.74, 0.72, and 0.51 respectively. FKBP11, also referred to as FKBP19, encodes FK506-binding protein 11. It is a member of the FKBP family of peptidyl-prolyl cis/trans isomerases, which accelerate the folding of proteins during protein synthesis. Recent studies have discovered that the differentiation of B cells into plasma cells is accompanied by the induction of FKBP11 expression, suggesting its potential role as a catalyst for antibody folding in plasma cells. In particular, the upregulation of FKBP11 expression has been observed to correlate with the induction of ER stress as part of the UPR pathway and in a manner that is dependent on the X-box-binding protein 1 (XBP1) [83].
13) PDIA5 was up-regulated within the fully protected group, with an average log2-fold change of 1.2. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 0.55, 0.54, and 0.32 respectively. PDIA5, also referred to as PDIR, encodes disulfide-isomerase A5 protein. It is a member of the disulfide isomerase (PDI) family of ER proteins that catalyze protein folding and thiol-disulfide interchange reactions. The domain organization of PDIR is atypical and different from other well-known members of the PDI family. PDIR stands out as the sole PDI consisting of one N-terminal non-catalytic domain and three catalytic domains. Upon analyzing the crystal structure of the non-catalytic domain of human PDIR, it became apparent that this domain serves as the primary binding site for the major ER chaperone calreticulin [84].
14) MYDGF was up-regulated within the fully protected group, with an average log2-fold change of 1.07. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 0.53, 0.51, and 0.34 respectively. MYDGF, also referred to as C19orf10 or IL-25, encodes paracrine-acting protein. It is highly conserved throughout evolution and can be found in various cellular compartments, including the ER, Golgi apparatus, and extracellular space [85]. MYDGF is produced by mucosal epithelial cells, and when it is overly expressed, it promotes eosinophilia and triggers the production of TH2-type cytokines [86]. Furthermore, it has been observed to activate the conventional pathways of the NF-κB through the phosphorylation of NF-κBp65 in germinal centre B cells [87].
15) PRDX4 was up-regulated within the fully protected group, with an average log2-fold change of 0.95. In contrast, the partially, weakly, and non-protected groups demonstrated lower average log2-fold changes of 0.33, 0.29, and 0.12 respectively. PRDX4, also referred to as AOE372, encodes an antioxidant enzyme and belongs to the peroxiredoxin family. It is located in the ER and plays a role in safeguarding against oxidative stress by detoxifying cellular peroxides [88]. However, the function of this protein goes beyond eliminating peroxide, it also promotes oxidative protein folding through the oxidation of PDI [89]. Furthermore, PRDX4 defines a reduction-oxidation pathway that specifically regulates the activity of NF-κB by modulating the phosphorylation of IκB-alpha in the cytoplasm [90].
16) XBP1 was up-regulated within the fully protected group, with an average log2-fold change of 0.75. In contrast, the partially, weakly, and non-protected groups demonstrated statically significant reductions, with average log2-fold changes of 0.22, 0.31, and 0.14 respectively. It is a basic-region leucine zipper protein in the CREB/ATF (cyclic AMP response element binding protein/activating transcription factor) family of transcription factors. XBP1 functions as a transcription factor during ER stress by facilitating the UPR pathway triggered by accumulated misfolded proteins [91], and has an additional function in protecting cells against oxidative stress [92]. Studies have revealed that the specific signals responsible for triggering plasma cell differentiation and the UPR pathway operate in synchronization through XBP1 to promote successful terminal B-cell differentiation [93–94]. The activation of XBP1 is important to maintain the optimal differentiation, functioning and survival of LLPCs with high secretory activity. However, recent studies revealed that the absence of XBP-1 only leads to a reduction rather than a total cessation of antibody secretion in plasma cells [95].
After thoroughly investigating the documented functionalities of each gene, we proceeded to investigate further and constructed a protein-protein interaction network using the list of 16 genes. This network substantially aids in the recognition of proteins that directly interact with one another, as well as the identification of the function of closely interconnected proteins. Interestingly, all of the proteins were found to have interactions, resulting in the creation of 2 densely interacting sub-networks (Fig. 4A). One of these sub-networks consisted of 8 genes that functionally enriched the gene ontology biological process termed regulation of B cell proliferation, a process that regulates the rate of B cell proliferation and has a direct correlation with germinal centre reactions and the frequency of terminal differentiation of B cells into ASCs. The other sub-network consisted of 8 genes that functionally enriched two gene ontology biological processes: endoplasmic reticulum unfolded protein response and cellular homeostasis, these two biological processes are closely linked to the essential adaption of the metabolism of ASCs to accommodate the elevated rate of protein biosynthesis required for antibody secretion. At the molecular level, the unfolded protein response denotes a series of molecular signals that emerge as a stress response due to the presence of unfolded proteins within the endoplasmic reticulum. These signals allow for the synchronization of protein synthesis rates with nutrient and energy stores, consequently facilitating the secretion of the required substantial amount of antibodies [96]. The functional enrichment of these sub-networks provided insights into the biological processes that, if compromised, could potentially hinder the ideal response to the vaccine.
The network's topological analysis indicates that XBP1, IRF4, HSP90B1 are the central hub nodes with the highest degrees of interactions and together they form the backbone of the network. They are crucial for maintaining the network's structure and functioning, which implies that any substantial reduction in the production of these proteins might impact the entire protein interaction network and consequently compromise the biological processes that are essential for an ideal vaccine response.
Genes with Significant Variations in log2-fold Change Between Participants Receiving the Vaccine for the First Time and those Repeatedly Vaccinated
Initially (day 0), a total of 123 seronegative participants received a single dose of TIIV. A group of 32 participants reported having received influenza vaccines in previous influenza seasons, irrespective of their diminished antibody level at day 0. Consequently, we assessed the immunogenicity of the vaccine in accordance with the participants' vaccination history, and it was observed that individuals who had received multiple previous vaccinations exhibited diminished rates of vaccine response within the confines of this study (Table 2). This outcome was expected since their previous vaccinations have not stimulated an effective immune response or may have only provided short-term protection.
Table 2
Participants’ seroprotection against the vaccine virus strains at 7 and 90 days post-vaccination. The data presented is categorized according to participants' vaccination history.
Seroprotected
Participants
|
First Vaccination (91 Participants)
|
Repeated Vaccination (32 Participants)
|
H1N1
|
H3N2
|
B1
|
H1N1
|
H3N2
|
B1
|
Day 0
|
0 (0.0%)
|
0 (0.0%)
|
0 (0.0%)
|
0 (0.0%)
|
0 (0.0%)
|
0 (0.0%)
|
Day 7
|
42 (46.15%)
|
34 (37.36%)
|
38 (41.76%)
|
12 (37.5%)
|
13 (40.62%)
|
11 (34.38%)
|
Day 90
|
59 (64.84%)
|
61 (67.03%)
|
71 (78.02%)
|
9 (28.13%)
|
15 (46.88%)
|
20 (62.5%)
|
Neither Day 7 nor Day 90 (Non-responders)
|
28 (30.77%)
|
26 (28.57%)
|
16 (17.58%)
|
18 (56.25%)
|
14 (43.75%)
|
9 (28.16%)
|
Only Day 7
(Short-term responders)
|
4 (4.4%)
|
4 (4.4%)
|
4 (4.4%)
|
5 (15.62%)
|
3 (9.37%)
|
3 (9.37%)
|
Only Day 90
(Late responders)
|
21 (23.08%)
|
31 (34.07%)
|
37 (40.66%)
|
2 (6.25%)
|
5 (15.62%)
|
12 (37.5%)
|
Day 7 and Day 90
(Ideal responders)
|
38 (41.76%)
|
30 (32.97%)
|
34 (37.36%)
|
7 (21.88%)
|
10 (31.25%)
|
8 (25.0%)
|
The fully protected group consisting of 11 participants, who responded ideally to the vaccine, had not previously received the vaccine. Conversely, the non-protected group, consisting of 42 participants who have demonstrated an inability to achieve the ideal response against any strain of the virus, included 14 out of 32 (43.75%) participants who had previously received an influenza vaccine and 28 out of 91 (30.76%) participants who had not previously received any influenza vaccine. Through analysis of variance of the gene expressions log2-fold change for the 16 potential genes (Supplementary Table 4), the differences in the mean log2-fold change had significantly increased across all genes when comparing the fully protected group to the repeatedly vaccinated non-protected group (Fig. 5). This group of 14 participants, who lacked ideal responses to any of the vaccine strains and showed either a short-term or no response after past vaccinations, exhibited the lowest gene expression levels of the potential genes, suggesting that the influence of these genes on the efficacy of the vaccine response is not coincidental, but rather a significant impact.