The role of B, CD4⁺T and CD8⁺T cells in both primary genital infection with attenuated herpes simplex virus type 2 (HSV-2) and development of protective immunity to a later challenge with virulent HSV-2 using lymphocyte-deficient mice has been elucidated. Following primary inoculation with attenuated thymidine kinase-deficient (TK⁻) HSV-2, B cell-deficient (μMT) mice developed a local viraemia and transient genital inflammation, suggesting a role for B cells in the innate control of local infection and inflammation. Natural antibodies are implicated in this process, as passive transfer of normal serum into μMT mice significantly reduced HSV-2 TK⁻shedding in the vaginal lumen, although it did not affect subsequent inflammation. Protection against lethal HSV-2 challenge was noted in HSV-2-vaccinated wild-type, CD8⁺T cell-deficient and μMT mice and was characterized by strong virus-specific IFN-γ responsesin vitroand delayed type hypersensitivity (DTH) responsesin vivo. In contrast, CD4⁺T cell-deficient (CD4^−/−) mice had impaired HSV-2-specific IFN-γ production and DTH responses and succumbed rapidly to genital HSV-2 challenge. However, protective responses to HSV-2 could be induced in HSV-2-vaccinated CD4^−/−mice by treatment with recombinant IFN-γ. Taken together, these results suggest that CD4⁺T cells secreting IFN-γ are critical for immune protection against lethal genital HSV-2 re-infection, whereas B cells/natural antibodies have anti-viral and -inflammatory effects in the innate control of a primary infection.

Cholera toxin B subunit (CTB) is an efficient mucosal carrier molecule for the generation of mucosal antibody responses and/or induction of systemic T-cell tolerance to linked antigens. CTB binds with high affinity to GM1 ganglioside cell surface receptors. In this study, we evaluated how conjugation of a peptide or protein antigen to CTB by chemical coupling or genetic fusion influences the T-cell-activating capacity of different antigen-presenting cell (APC) subsets. Using an in vitro system in which antigen-pulsed APCs were incubated with antigen-specific, T-cell receptor-transgenic T cells, we found that the dose of antigen required for T-cell activation could be decreased >10,000-fold using CTB-conjugated compared to free antigen. In contrast, no beneficial effects were observed when CTB was simply admixed with antigen. CTB conjugation enhanced the antigen-presenting capacity not only of dendritic cells and B cells but also of macrophages, which expressed low levels of cell surface major histocompatibility complex (MHC) class II and were normally poor activators of naive T cells. Enhanced antigen-presenting activity by CTB-linked antigen resulted in both increased T-cell proliferation and increased interleukin-12 and gamma interferon secretion and was associated with up-regulation of CD40 and CD86 on the APC surface. These results imply that conjugation to CTB dramatically lowers the threshold concentration of antigen required for immune cell activation and also permits low-MHC II-expressing APCs to prime for a specific immune response.

(1) Background: Tannic acid is a plant-derived polyphenol showing antiviral activity mainly because of an interference with the viral adsorption. In this work, we tested whether the modification of silver nanoparticles with tannic acid (TA-AgNPs) can provide a microbicide with additional adjuvant properties to treat genital herpes infection. (2) Methods: The mouse model of the vaginal herpes simplex virus 2 (HSV-2) infection was used to test immune responses after treatment of the primary infection with TA-AgNPs, and later, after a re-challenge with the virus. (3) Results: The mice treated intravaginally with TA-AgNPs showed better clinical scores and lower virus titers in the vaginal tissues soon after treatment. Following a re-challenge, the vaginal tissues treated with TA-AgNPs showed a significant increase in the percentages of IFN-gamma+ CD8+ T-cells, activated B cells, and plasma cells, while the spleens contained significantly higher percentages of IFN-gamma+ NK cells and effector-memory CD8+ T cells in comparison to NaCl-treated group. TA-AgNPs-treated animals also showed significantly better titers of anti-HSV-2 neutralization antibodies in sera; and (4) Conclusions: Our findings suggest that TA-AgNPs sized 33 nm can be an effective anti-viral microbicide to be applied upon the mucosal tissues with additional adjuvant properties enhancing an anti-HSV-2 immune response following secondary challenge.

Cholera toxin (CT) is a strong mucosal adjuvant for codelivered antigens, whereas its nontoxic B subunit (CTB) is an efficient mucosal carrier molecule for the generation of immune responses to linked antigens. We investigated the effects of CT and CTB on the immunogenicity of in vitro-treated antigen-pulsed dendritic cells (DC) following intravenous injection into mice. Prior to infusion, DC were pulsed for 90 min with either free ovalbumin (OVA), OVA mixed with CT or CTB, or chemical conjugates of OVA with CT and CTB (OVA-CT and OVA-CTB). DC pulsed with OVA or with OVA and CTB gave rise to modest antibody and T-cell responses. Conjugation of OVA with CTB enhanced both the subsequent B-cell and T-cell responses to OVA and preferentially induced Th2 responses. CT was shown to be a strong adjuvant when it was coadministered to DC with OVA and was even stronger when it was coadministered with OVA-CTB and primed for a mixed Th1-Th2 response. The antibody and T-cell responses were further enhanced if OVA was coupled to CT, implying that CT can utilize a combined carrier and adjuvant function vis-a-vis linked antigens for DC vaccination. The immunopotentiating capacity of CT- and CTB-linked antigen was associated with both upregulated secretion of interleukin-1β by the pulsed DC and increased expression of CD80 and CD86 on the DC surface. These results imply that CT and CTB can be used to both markedly increase and partially direct the DC vaccine-induced immune response with respect to Th1 and Th2 responses, which has obvious implications for DC-based vaccine development.

Introduction: The tumour necrosis factor (TNF) family ligands BAFF (B-cell activating factor of TNF family) and APRIL (a proliferation-inducing ligand) are essential for B-cell survival and function. Elevated serum levels of BAFF and APRIL have been reported earlier in patients with systemic lupus erythematosus (SLE). Since autoantibody formation in the central nervous system (CNS) is a distinct feature of neuropsychiatric SLE (NPSLE), we have investigated whether NPSLE is associated with an enhanced intrathecal production of APRIL and BAFF. Methods: Levels of BAFF and APRIL in cerebrospinal fluid (CSF) and serum from healthy controls, SLE patients without CNS involvement, and patients with NPSLE were determined by enzyme-linked immunosorbent assay. Interleukin-6 (IL-6) levels were determined by an IL-6-specific bioassay. Results: SLE patients had levels of APRIL in CSF that were more than 20-fold higher and levels of BAFF in CSF that were more than 200-fold higher than those of healthy controls. Separate analyses of SLE patients with and without CNS involvement revealed that NPSLE patients had enhanced levels of APRIL in CSF. BAFF and APRIL were likely produced locally in the CNS as CSF and serum levels did not correlate. Moreover, CSF levels of APRIL correlated with BAFF but not with IL-6, suggesting that APRIL and BAFF in the CNS are regulated together but that they are produced independently of IL-6. Conclusion: To our knowledge this is the first study to show elevated levels of BAFF and APRIL in CSF of SLE patients. APRIL was augmented in NPSLE patients compared with SLE patients without CNS involvement. APRIL and BAFF antagonists breeching the blood-brain barrier therefore could have beneficial effects on SLE patients, in particular patients with NPSLE.