A simple generic peptide-based vaccine structure that targets Toll-like receptor 2-expressing dendritic cells and causes their activation is described. The vaccines are totally synthetic, serve as their own adjuvant, and are composed of (i) a single helper T cell epitope, (ii) a target epitope that is either recognized by CD8⁺T cells or B cells, and (iii) a Toll-like receptor 2-targeting lipid moiety,S-[2,3-bis(palmitoyloxy)propyl]cysteine, that is situated between the peptide epitopes to form a branched configuration. The different CD8⁺T cell epitopes examined were from (i) influenza virus, (ii) the intracellular bacteriumListeria monocytogenes, and (iii) ovalbumin as a model tumor antigen. Vaccines containing a B cell epitope from gastrin or luteinizing hormone-releasing hormone as a B cell epitope were also examined for their ability to elicit antibody against the parent hormones. Each of the vaccines was capable of inducing either CD8⁺T cell or antibody-mediated immune responses. The lipidated vaccines, but not the nonlipidated vaccines, were able to mediate protection against viral or bacterial infection and mediate prophylactic and therapeutic anticancer activity. The two hormone-based vaccines induced high antibody titers, which in the case of luteinizing hormone-releasing hormone resulted in abrogation of reproductive function. These results highlight the utility of simple, totally synthetic, epitope-based vaccines.

Cigarette smoke has both pro-inflammatory and immunosuppressive effects. Both active and passive cigarette smoke exposure are linked to an increased incidence and severity of respiratory virus infections, but underlying mechanisms are not well defined. We hypothesized, based on prior gene expression profiling studies, that upregulation of pro-inflammatory mediators by short term smoke exposure would be protective against a subsequent influenza infection. BALB/c mice were subjected to whole body smoke exposure with 9 cigarettes/day for 4 days. Mice were then infected with influenza A (H3N1, Mem71 strain), and analyzed 3 and 10 days later (d3, d10). These time points are the peak and resolution (respectively) of influenza infection. Inflammatory cell influx into the bronchoalveolar lavage (BALF), inflammatory mediators, proteases, histopathology, viral titres and T lymphocyte profiles were analyzed. Compared to smoke or influenza alone, mice exposed to smoke and then influenza had more macrophages, neutrophils and total lymphocytes in BALF at d3, more macrophages in BALF at d10, lower net gelatinase activity and increased activity of tissue inhibitor of metalloprotease-1 in BALF at d3, altered profiles of key cytokines and CD4+ and CD8+ T lymphocytes, worse lung pathology and more virus-specific, activated CD8+ T lymphocytes in BALF. Mice smoke exposed before influenza infection had close to 10-fold higher lung virus titres at d3 than influenza alone mice, although all mice had cleared virus by d10, regardless of smoke exposure. Smoke exposure caused temporary weight loss and when smoking ceased after viral infection, smoke and influenza mice regained significantly less weight than smoke alone mice. Smoke induced inflammation does not protect against influenza infection. In most respects, smoke exposure worsened the host response to influenza. This animal model may be useful in studying how smoke worsens respiratory viral infections.

Improving the immunological potency, particularly the Ab response, is a serious hurdle for the protective efficacy and hence broad application of DNA vaccines. We examined the immunogenicity and protective efficacy of a hemagglutinin-based influenza DNA vaccine that was targeted to antigen-presenting cells (APCs) by fusion to CTLA4. The targeted vaccine was shown to induce an accelerated and increased Ab response (as compared with those receiving the nontargeted control) that was predominated by IgG1 and recognized conformationally dependent viral epitopes. Moreover, mice receiving the APC-targeted DNA vaccine had significantly reduced viral titers (100-fold) after a nonlethal virus challenge. The increased protective efficacy was most likely because of increased Ab responses, as cytotoxic T lymphocyte responses were not enhanced. Targeting was demonstrated by direct binding studies of CTLA4 fusion proteins to the cognate ligand (B7; expressed on APCs in vivo ). In addition, a targeted protein was detected at 4-fold higher levels in draining lymph nodes within 2–24 h of administration. Therefore, this study demonstrates that targeting DNA-encoded antigen to APCs results in enhanced immunity and strongly suggests that this approach may be useful in improving the protective efficacy of DNA vaccines.

The longevity of the influenza virus‐specific CD8⁺ T cell response following intranasal delivery of a synthetic lipopeptide was investigated and the characteristics and location of the cells associated with viral clearance examined. The lipopeptide, incorporating an epitope for CD8⁺ T cells and another for CD4⁺ T cells with the lipid moiety S‐[2,3‐bis(palmitoyloxy)propyl]cysteine (Pam2Cys) attached, induced potent and long‐lived pulmonary protection. Both the lipopeptide and its largely unprotective non‐lipidated counterpart elicited comparable numbers of CD8⁺ T cells in the spleen, which was the main location of the memory pool. However, the lipopeptide, unlike the non‐lipidated peptide, also induced a substantial memory population that remained in the lungs and was rapidly activated upon viral challenge months later. These lipopeptide‐induced lung‐resident CD8⁺ T cells were also very similar in number and IFN‐γ‐secreting potential to those induced by prior exposure to the virus itself and are likely mediators of initial viral clearance prior to recruitment from the expanding lymph node T cell pool. Significant clearing responses were demonstrated as late as 9 months post‐lipopeptide vaccination. This study shows that CD8⁺ T cells primed by the lipopeptide are not only long‐lived but can take up residence in the lung where they are important early mediators of pulmonary protection.