BACKGROUNDThe West African outbreak of Ebola virus disease that peaked in 2014 has caused more than 11,000 deaths. The development of an effective Ebola vaccine is a priority for control of a future outbreak. METHODSIn this phase 1 study, we administered a single dose of the chimpanzee adenovirus 3 (ChAd3) vaccine encoding the surface glycoprotein of Zaire ebolavirus (ZEBOV) to 60 healthy adult volunteers in Oxford, United Kingdom. The vaccine was administered in three dose levels -1×10 10 viral particles, 2.5×10 10 viral particles, and 5×10 10 viral particles -with 20 participants in each group. We then assessed the effect of adding a booster dose of a modified vaccinia Ankara (MVA) strain, encoding the same Ebola virus glycoprotein, in 30 of the 60 participants and evaluated a reduced prime-boost interval in another 16 participants. We also compared antibody responses to inactivated whole Ebola virus virions and neutralizing antibody activity with those observed in phase 1 studies of a recombinant vesicular stomatitis virus-based vaccine expressing a ZEBOV glycoprotein (rVSV-ZEBOV) to determine relative potency and assess durability. RESULTSNo safety concerns were identified at any of the dose levels studied. Four weeks after immunization with the ChAd3 vaccine, ZEBOV-specific antibody responses were similar to those induced by rVSV-ZEBOV vaccination, with a geometric mean titer of 752 and 921, respectively. ZEBOV neutralization activity was also similar with the two vaccines (geometric mean titer, 14.9 and 22.2, respectively). Boosting with the MVA vector increased virus-specific antibodies by a factor of 12 (geometric mean titer, 9007) and increased glycoprotein-specific CD8+ T cells by a factor of 5. Significant increases in neutralizing antibodies were seen after boosting in all 30 participants (geometric mean titer, 139; P<0.001). Virus-specific antibody responses in participants primed with ChAd3 remained positive 6 months after vaccination (geometric mean titer, 758) but were significantly higher in those who had received the MVA booster (geometric mean titer, 1750; P<0.001). CONCLUSIONSThe ChAd3 vaccine boosted with MVA elicited B-cell and T-cell immune responses to ZEBOV that were superior to those induced by the ChAd3 vaccine alone. (Funded by the Wellcome Trust and others; ClinicalTrials.gov number, NCT02240875.)A BS TR AC T

In humans and mice, CD8α+ conventional dendritic cells are the primary source of interferon-λ released in response to the adjuvant and Toll-like receptor 3 agonist poly IC.

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The use of classical smallpox vaccines based on vaccinia virus (VV) is associated with severe complications in both naïve and immune individuals. Modified vaccinia virus Ankara (MVA), a highly attenuated replicationdeficient strain of VV, has been proven to be safe in humans and immunocompromised animals, and its efficacy against smallpox is currently being addressed. Here we directly compare the efficacies of MVA alone and in combination with classical VV-based vaccines in a cynomolgus macaque monkeypox model. The MVA-based smallpox vaccine protected macaques against a lethal respiratory challenge with monkeypox virus and is therefore an important candidate for the protection of humans against smallpox.

The uptake of respiratory syncytial virus (RSV) antigen by cattle dendritic cells was investigated. Pathways of antigen uptake were monitored by flow cytometry using specific tracers and by proliferation assays, which were used to measure the presentation of RSV antigen and ovalbumin. Inhibitors that differentially affected pathways were used to distinguish them. Presentation of RSV antigen, but not ovalbumin, was inhibited by phorbol myristate acetate and filipin, which have been reported to inhibit caveolae, but not by cytochalasin D, amiloride, or mannose. These inhibitors have been reported to block macropinocytosis and other actin-dependent uptake mechanisms, endocytic pathways involving clathrin-coated pits, and the mannose receptor. Furthermore, co-localization of RSV antigen and caveolae was observed by confocal microscopy. Thus, the major route for uptake of RSV antigen by cattle dendritic cells is one mediated by caveolae, adding a pathway of antigen uptake by dendritic cells to those established. J. Leukoc. Biol. 66: 50-58; 1999.

Poxviruses such as the causative agent of smallpox have developed multiple strategies to suppress immune responses, including the suppression of DC activation. Since poxviruses are large DNA viruses, we hypothesized that their detection by DCs may involve the endosomal DNA recognition receptor TLR9. Indeed, we have shown here that DC recognition of ectromelia virus (ECTV), the causative agent of mousepox, completely depended on TLR9. The importance of TLR9 was highlighted by the fact that mice lacking TLR9 showed drastically increased susceptibility to infection with ECTV. In contrast, we found that the strongly attenuated poxvirus modified vaccinia virus Ankara (MVA) activated DCs by both TLR9-dependent and -independent pathways. We therefore tested whether we could use the broader induction of immune responses by MVA to protect mice from a lethal infection with ECTV. Indeed, MVA given at the same time as a lethal dose of ECTV protected mice from death. Importantly, MVA also rescued TLR9-deficient mice if administered 2 full days after an otherwise lethal infection with ECTV. Therefore, these data suggest an essential role for TLR9 in the defense against poxviruses. In addition, postexposure application of MVA may protect against lethal poxvirus infection.

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Smallpox vaccination with replication deficient vaccinia strains such as Modified Vaccinia-Ankara (MVA) may induce protective immunity with improved safety and tolerability profiles compared with currently available smallpox vaccines. Ninety subjects were randomized equally to 6 groups in a partially blinded, randomized control clinical trial. IMVAMUNE ® (MVA-BN ® , Bavarian Nordic A/S, Kvistgård, Denmark) vaccine or placebo was administered at Study Day 0 and 28 by subcutaneous or intramuscular injection and five groups were challenged with Dryvax ® at study Day 112. Vaccination with two doses of IMVAMUNE ® was safe and well-tolerated compared to Dryvax ® . IMVAMUNE ® produced comparable cellular and humoral immune responses to one dose of Dryvax ® and the immunity induced appears robust 90 days post vaccination by evidence of attenuated primary cutaneous reaction responses following Dryvax ® . IMVAMUNE ® vaccination prior to Dryvax ® reduced virus replication at the Dryvax ® site, decreased the size of the primary cutaneous lesion, and decreased the time to healing but did not completely ameliorate the immune response. MO 63110,, E-mail address: E-mail: freyse@slu.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. In a recent study, IMVAMUNE ® , a highly attenuated vaccinia strain derived from MVA-572 (obtained from Dr. Anton Mahr), does not replicate in human cells and was safe and immunogenic in humans [9]. The present study sought to evaluate the safety and immunogenicity of a range of doses and routes of administration of IMVAMUNE ® . Potential surrogate efficacy of MVA-induced immune responses was evaluated by the ability of two doses of IMVAMUNE ® to reduce the clinical effects of a Dryvax ® challenge. Keywords NIH Public Access Author Manuscript Methods Vaccines and DiluentsIMVAMUNE ® (Bavarian Nordic A/S, Kvistgård, Denmark), a modified vaccinia Ankara vaccine (lot no. 130303), is a non-replicating virus in human cells used as the MVA smallpox vaccine in this study. Lyophilized vaccine was reconstituted with sterile water for injection (WFI) (Impfstoffwerk Dessau-Thornau GmbH, Germany). The reconstituted vaccine contains approximately 2 × 10 8 TCID 50 per ml. The placebo was sterile saline for injection (American Regent Laboratories, Inc, Shirley, NY). Licensed smallpox vaccine (Dryvax ® , Wyeth Laboratories, Marietta, PA) (lot no. 4008284), a replicating vaccinia virus provided by the Centers for Disease Control and Prevention in Atlanta, GA, was used as both the comparator vaccine and the virus in the challenge portion of this study.Reconstituted IM...