No vaccine against methicillin-resistantStaphylococcus aureus(MRSA) has been currently approved for use in humans.Staphylococcusenterotoxin B (SEB) is one of the most potent MRSA exotoxins. In the present study, we evaluated the efficacy and immunologic mechanisms of an SEB multiple B-cell epitope vaccine against MRSA infection. Synthetic overlapping peptide ELISA identified three novel B-cell immunodominant SEB epitopes (in addition to those previously known): SEB_31–48, SEB_133–150and SEB_193–210. Six B-cell immunodominant epitopes (amino acid residues 31–48, 97–114, 133–150, 193–210, 205–222 and 247–261) were sufficient to induce robust IgG1/IgG2b-specific protective responses against MRSA infection. Therefore, we constructed a recombinant MRSA SEB-specific multiple B-cell epitope vaccine Polypeptides by combining the six SEB immunodominant epitopes and demonstrated its ability to induce a robust SEB-specific IgG1 response to MRSA, as well as a Th2-directing isotype response. Moreover, Polypeptides-induced antisera stimulated synergetic opsonophagocytosis killing of MRSA. Most importantly, Polypeptides was more effective at clearing the bacteria in MRSA-infected mice than the whole SEB antigen and was able to successfully protect mice from infection by various clinical MRSA isolates. Altogether, these results support further evaluation of the SEB multiple B-cell epitope-vaccine to address MRSA infection in humans.

Helicobacter pylori (H. pylori) infects more than half of the world’s population, causing chronic gastritis, peptic ulcers and gastric cancer. Urease B subunit (UreB), a conserved protein of H. pylori, is capable of inducing specific CD4⁺ T-cell responses and provides protection against this infection. Previous studies have confirmed the effectiveness of rUreB subunit vaccines in generating CD4⁺ T-cell-mediated protection, but less is known regarding the roles of different subtypes of T-cell immunity, such as Th1, Th2 and Th17, particularly the immunodominant epitopes inducing specific CD4⁺ T-cell responses, in vaccine-mediated protection. In this study, we demonstrated that the vaccination of BALB/c mice with rUreB resulted in significant antigen-specific Th1 and Th17 immune responses. Importantly, two novel Th epitopes, UreB_317–329 and UreB_409–421, which are recognized by a major population of CD4⁺ T cells, were identified in immunized mice. Our results demonstrated that two novel epitopes can simultaneously induce Th1 and Th17 immune responses; however, only the epitope vaccine-induced CD4⁺ T-cells secreting IFN-γ mediated the protection against H. pylori; cells secreting IL-17A did not. Taken together, our results suggest that two novel immunodominant epitopes can induce Th1 and Th17 immune responses, but only the induced Th1 lymphocytes mediate protection against H. pylori.

Background: Chronic hepatitis B (CHB) remains a significant global health problem, leading to recurrent inflammation and liver-damaging diseases such as fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Currently, although diagnostic markers for CHB are well established, the indicators for predicting liver injury caused by hepatitis B virus (HBV) infection still need to be further explored. Thus, the identification of credible infectious indicators is urgently needed to facilitate timely clinical intervention and avoid the progression of disease malignancy.Methods: The Gene Expression Omnibus (GEO) database GSE83148 data set was used to explore the hub genes for HBV infection. The quantitative real-time polymerase chain reaction (qPCR) was used to identify the impact of HBV infection on the expression of hub gene at the cell level. At the same time, serum samples and clinical information were collected from healthy, HBV-free and CHB patients. The enzyme-linked immunosorbent assay (ELISA) was used to verify the results of cell experiments and Pearson correlation analysis was used to clarify hub genes correlation with HBV infection indicators and liver injury-related indicators. Finally, the Gene Expression Profiling Interactive Analysis (GEPIA) database was used to analyze the differences in the expression of hub gene in liver injury diseases.Results: Chemokine (C-X-C motif) ligand (CXCL)8, CXCL9, CXCL10, and CXCL11 were identified as hub genes in HBV infection. After HBV infection, the expression of the four chemokines was significantly increased and the concentrations secreted into serum were also increased. Moreover, the four chemokines were significantly correlated with HBV infection-related indicators and liver injury-related indicators, which were positively correlated with alanine aminotransferase (ALT), aspartate aminotransferase (AST) and hepatitis B e antigen (HBeAg), and negatively correlated with AST/ALT ratio and hepatitis B core antibody (HBcAb). In addition, the expression of CXCL9, CXCL10, and CXCL11 in HCC tissues was significantly higher than in normal tissues.Conclusion: Using a combination of bioinformatics, cell experiments, and clinical correlation analysis, this study showed that CXCL8, CXCL9, CXCL10, and CXCL11 can be used as serum biomarkers to forecast liver injury caused by HBV infection.

Immunodominant antigens that induce Th1 and Th17 responses protect mice against Helicobacter pylori infection Immunodominant antigens that induce Th1 and Th17 responses protect mice against Helicobacter Pylori infection

Objective Helicobacter pylori infection has been reported to aggravate rheumatoid arthritis (RA), but the relevant mechanism remains unclear. This study aimed to investigate the underlying pathogenic mechanism of H. pylori infection in the progression of RA. Methods The Disease Activity Score (DAS-28) and serum anticitrullinated protein antibody (ACPA) levels were compared between H. pylori-negative and H. pylori-positive patients with RA. MH7A cells were stimulated with polyclonal ACPA purified from the peripheral blood of patients with RA. The citrullination levels were assessed by western blot in GES-1 cells and sera. ChIP, luciferase reporter assays, mass spectrometry and ELISA were applied to explore the molecular mechanism of H. pylori infection in RA progression. Results The DAS-28 and ACPA levels of patients with RA in the H. pylori-positive group were significantly higher than those in the H. pylori-negative group. Polyclonal ACPA derived from H. pylori-positive patients promoted cell proliferation and induced secretion of IL-6 and IL-8. For the first time, we found that H. pylori infection induces cellular protein citrullination by upregulating protein arginine deiminase type 4 (PAD4). Furthermore, we confirmed a direct functional binding of hypoxia-inducible factor 1α on the PADI4 gene promoter. We demonstrated that PAD4 interacts with and citrullinates keratin 1 (K1), and serum and synovial fluid levels of anti-Cit-K1 antibody were markedly increased in H. pylori-infected patients with RA. Conclusion Our findings reveal a novel mechanism by which H. pylori infection contributes to RA progression. Therapeutic interventions targeting H. pylori may be a viable strategy for the management of RA.

Subtype specificity of influenza A virus (IAV) is determined by its two surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA). For HA, 16 distinct subtypes (H1–H16) exist, while nine exist for NA. The epidemic strains of H1N1 IAV change frequently and cause annual seasonal epidemics as well as occasional pandemics, such as the notorious 1918 influenza pandemic. The recent introduction of pandemic A/H1N1 IAV (H1N1pdm virus) into humans re-emphasizes the public health concern about H1N1 IAV. Several studies have identified conserved epitopes within specific HA subtypes that can be used for diagnostics. However, immune specific epitopes in H1N1 IAV have not been completely assessed. In this study, linear epitopes on the H1N1pdm viral HA protein were identified by peptide scanning using libraries of overlapping peptides against convalescent sera from H1N1pdm patients. One epitope, P5 (aa 58–72) was found to be immunodominant in patients and to evoke high titer antibodies in mice. Multiple sequence alignments and in silico coverage analysis showed that this epitope is highly conserved in influenza H1 HA [with a coverage of 91.6% (9,860/10,767)] and almost completely absent in other subtypes [with a coverage of 3.3% (792/23,895)]. This previously unidentified linear epitope is located outside the five well-recognized antigenic sites in HA. A peptide ELISA method based on this epitope was developed and showed high correlation (χ² = 51.81, P<0.01, Pearson correlation coefficient R = 0.741) with a hemagglutination inhibition test. The highly conserved H1 subtype-specific immunodominant epitope may form the basis for developing novel assays for sero-diagnosis and active surveillance against H1N1 IAVs.