Background The worst Ebola virus disease (EVD) outbreak in history has resulted in more than 28,000 cases and 11,000 deaths. We present the final results of two phase 1 trials of an attenuated, replication-competent, recombinant vesicular stomatitis virus (rVSV)–based vaccine candidate designed to prevent EVD. Methods We conducted two phase 1, placebo-controlled, double-blind, dose-escalation trials of an rVSV-based vaccine candidate expressing the glycoprotein of a Zaire strain of Ebola virus (ZEBOV). A total of 39 adults at each site (78 participants in all) were consecutively enrolled into groups of 13. At each site, volunteers received one of three doses of the rVSV-ZEBOV vaccine (3 million plaque-forming units [PFU], 20 million PFU, or 100 million PFU) or placebo. Volunteers at one of the sites received a second dose at day 28. Safety and immunogenicity were assessed. Results The most common adverse events were injection-site pain, fatigue, myalgia, and headache. Transient rVSV viremia was noted in all the vaccine recipients after dose 1. The rates of adverse events and viremia were lower after the second dose than after the first dose. By day 28, all the vaccine recipients had seroconversion as assessed by an enzyme-linked immunosorbent assay (ELISA) against the glycoprotein of the ZEBOV-Kikwit strain. At day 28, geometric mean titers of antibodies against ZEBOV glycoprotein were higher in the groups that received 20 million PFU or 100 million PFU than in the group that received 3 million PFU, as assessed by ELISA and by pseudovirion neutralization assay. A second dose at 28 days after dose 1 significantly increased antibody titers at day 56, but the effect was diminished at 6 months. Conclusions This Ebola vaccine candidate elicited anti-Ebola antibody responses. After vaccination, rVSV viremia occurred frequently but was transient. These results support further evaluation of the vaccine dose of 20 million PFU for preexposure prophylaxis and suggest that a second dose may boost antibody responses. (Funded by the National Institutes of Health and others; rVSVΔG-ZEBOV-GP ClinicalTrials.gov numbers, NCT02269423 and NCT02280408.)

Major histocompatibility complex (MHC) class I-deficient cell lines were used to demonstrate that the MHC class II transactivator (CIITA) can induce surface expression of MHC class I molecules. CIITA induces the promoter of MHC class I heavy chain genes. The site alpha DNA element is the target for CIITA-induced transactivation of class I. In addition, interferon-gamma (IFNgamma)-induced MHC class I expression also requires an intact site alpha. The G3A cell line, which is defective in CIITA induction, does not induce MHC class I antigen and promoter in response to IFNgamma. Trans-dominant-negative forms of CIITA reduce class I MHC promoter function and surface antigen expression. Collectively, these data argue that CIITA has a role in class I MHC gene induction.

We Numerous strategies for enhancing the immune response to autologous tumors have recently been developed. Many of the approaches directly target the activation of tumor-specific CD8 ϩ effector T lymphocytes, since these cells are efficient mediators of tumor-specific immunity (1). In contrast, we (2, 3) and others (4-6) have reasoned that improved generation of tumor-specific CD4 ϩ T helper cells enables tumor-specific CD8 ϩ T cells to function more efficiently and, therefore, have focused on activating CD4 ϩ T cells. We have used gene transfection to express syngeneic major histocompatibility complex (MHC) class II genes in tumor cells so that the tumor cells can directly present tumor peptides to CD4 ϩ T helper lymphocytes and bypass the need for host antigen-presenting cells (APC) and soluble tumor antigen. Immunization of autologous mice with class II-transfected tumor cells protects against subsequent challenges of wild-type (class II Ϫ ) primary tumor in a sarcoma model (2), decreases metastatic disease in two melanoma models (7), and mediates regression of a wild-type, long-term established, solid tumor in a sarcoma model (8). T cell depletion experiments established that class II-transfected tumor cells stimulate tumor-specific CD4 ϩ T cells because they are more immunogenic than wild-type class II Ϫ tumor cells (2,8). Immunization with class II-transfected tumor cells, therefore, induces a potent tumor-specific immunity that could be exploited for immunotherapy.To develop the CD4 ϩ T cell activation strategy and methods for predicting its potential clinical application, we are exploring additional approaches to enhance MHC class II expression. The two most practical of these approaches, interferon ␥ (IFN-␥) treatment (9) and class II transactivator (CIITA) gene transduction (10), not only increase autologous MHC class II expression but also up-regulate class II-associated accessory molecules, such as invariant (Ii) chain and DM (11-13). If IFN-␥ treatment and͞or CIITA gene expression are to be considered as immunotherapeutic strategies for treating tumor-bearing patients, the effects of class II-associated accessory molecule expression on class II-transfected tumor cell immunogenicity should be determined. We have, therefore, generated and determined the tumorigenicity of various sarcoma transfectants expressing different combinations of syngeneic MHC class II, Ii, and DM. Since we originally hypothesized that class II-transfected tumor cells that do not coexpress class II accessory molecules will present endogenously synthesized tumor peptides (2, 3), we have also assessed the ability of the various transfectants and transductants to present MHC class II-restricted antigen to antigen-specific CD4 ϩ T cells. Our results demonstrate that tumor cells expressing syngeneic MHC class II without coexpression of Ii and DM are the only transfectants͞transductants that induce tumorspecific immunity and efficiently present class II-restricted, endogenously synthesized antigens. Tumor cell coexpression o...

SummaryBackground The 2014 Zaire Ebola virus outbreak highlighted the need for a safe, effective vaccine with a rapid onset of protection. We report the safety and immunogenicity of the recombinant vesicular stomatitis virus-Zaire Ebola virus envelope glycoprotein vaccine (rVSV∆G-ZEBOV-GP) across a 6 log 10 dose range in two sequential cohorts.

Virus-like particles (VLPs) present viral antigens in a native conformation and are effectively recognized by the immune system and therefore are considered as suitable and safe vaccine candidates against many viral diseases. Here we demonstrate that chimeric VLPs containing Rift Valley fever virus (RVFV) glycoproteins GN and GC, nucleoprotein N and the gag protein of Moloney murine leukemia virus represent an effective vaccine candidate against Rift Valley fever, a deadly disease in humans and livestock. Long-lasting humoral and cellular immune responses are demonstrated in a mouse model by the analysis of neutralizing antibody titers and cytokine secretion profiles. Vaccine efficacy studies were performed in mouse and rat lethal challenge models resulting in high protection rates. Taken together, these results demonstrate that replication-incompetent chimeric RVF VLPs are an efficient RVFV vaccine candidate.

The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to evaluate the safety and characteristics of live, recombinant viral vector vaccines. A recent publication by the V3SWG described live, attenuated, recombinant vesicular stomatitis virus (rVSV) as a chimeric virus vaccine for HIV-1 (Clarke et al., 2016). The rVSV vector system is being explored as a platform for development of multiple vaccines. This paper reviews the molecular and biological features of the rVSV vector system, followed by a template with details on the safety and characteristics of a rVSV vaccine against Zaire ebolavirus (ZEBOV). The rVSV-ZEBOV vaccine is a live, replication competent vector in which the VSV glycoprotein (G) gene is replaced with the glycoprotein (GP) gene of ZEBOV. Multiple copies of GP are expressed and assembled into the viral envelope responsible for inducing protective immunity. The vaccine (designated V920) was originally constructed by the National Microbiology Laboratory, Public Health Agency of Canada, further developed by NewLink Genetics Corp. and Merck & Co., and is now in final stages of registration by Merck. The vaccine is attenuated by deletion of the principal virulence factor of VSV (the G protein), which also removes the primary target for anti-vector immunity. The V920 vaccine caused no toxicities after intramuscular (IM) or intracranial injection of nonhuman primates and no reproductive or developmental toxicity in a rat model. In multiple studies, cynomolgus macaques immunized IM with a wide range of virus doses rapidly developed ZEBOV-specific antibodies measured in IgG ELISA and neutralization assays and were fully protected against lethal challenge with ZEBOV virus. Over 20,000 people have received the vaccine in clinical trials; the vaccine has proven to be safe and well tolerated. During the first few days after vaccination, many vaccinees experience a mild acute-phase reaction with fever, headache, myalgia, and arthralgia of short duration; this period is associated with a low-level viremia, activation of anti-viral genes, and increased levels of chemokines and cytokines. Oligoarthritis and rash appearing in the second week occur at a low incidence, and are typically mild-moderate in severity and self-limited. V920 vaccine was used in a Phase III efficacy trial during the West African Ebola epidemic in 2015, showing 100% protection against Ebola Virus Disease, and it has subsequently been deployed for emergency control of Ebola outbreaks in central Africa. The template provided here provides a comprehensive picture of the first rVSV vector to reach the final stage of development and to provide a solution to control of an alarming human disease.

CIITA is the master regulator of class II major histocompatibility complex gene expression. We present evidence that CIITA can self-associate via two domains: the C terminus (amino acids 700 to 1130) and the GTP-binding domain (amino acids 336 to 702). Heterotypic and homotypic interactions are observed between these two regions. Deletions within the GTP-binding domain that reduce GTP-binding and transactivation function also reduce self-association. In addition, two leucine residues in the C-terminal leucine-rich repeat region are critical for self-association as well as function. This study reveals for the first time a complex pattern of CIITA self-association. These interactions are discussed with regard to the apoptosis signaling proteins, Apaf-1 and Nod1, which share domain arrangements similar to those of CIITA.Major histocompatibility complex (MHC) class II proteins play a critical role in the initiation of immune responses by presenting peptides from exogenous antigens to T-helper lymphocytes (11,48). The expression of MHC class II genes is restricted to specific cell types with constitutive expression in B lymphocytes and dendritic cells. In addition, a variety of cell types can be induced to express MHC class II by the proinflammatory cytokine gamma interferon.The cis-acting elements and the DNA-binding transcription factors that regulate MHC class II expression have been extensively characterized (6,20). MHC class II gene promoters all contain a well-conserved tripartite arrangement of S, X, and Y sequence elements. The X box can be subdivided into X1 and X2 elements. The class II X1 box binding factor, RFX, has been shown to be defective in a rare immune deficiency, bare lymphocyte syndrome (BLS) (38, 50). Genetic complementation of the defects in these cells resulted in the identification of the components for this DNA-binding transcription factor. RFX is composed of three subunits: RFX5 (56), RFXAP (17), and RFX-B (RFXANK) (43, 46). The X2 element binding protein has recently been identified as CREB (45). While the X box is uniquely present in MHC class II promoters, the Y box is a CCAAT box that is present in a large number of eukaryotic promoters (9, 41). This site is bound by yet another heterotrimeric factor, NF-Y (40, 52).Although the transcription factors that bind the class II boxes are required for the expression of MHC class II genes, their presence alone is not sufficient for transcriptional activation. A major breakthrough in understanding MHC class II gene expression was provided by complementation studies using the mutant cell line, RJ2.25 (1, 57). The initial isolation of the CIITA cDNA revealed a large protein with an open reading frame encoding 1,130 amino acids (57). CIITA is sufficient for induction of MHC class II gene expression when introduced into cells (10,14,58). In certain cases it also has been implicated in the upregulation of MHC class I transcription (21,42). The N terminus of CIITA contains an acidic domain that can activate transcription when fused to the DNA-binding ...

The clinical manifestations and geographic distribution of loiasis overlap with those of other human filarial parasites, presenting challenges in the specific diagnosis of loiasis that may lead to delays in appropriate therapy. A recombinant antigen (Ll-SXP-1), preferentially recognized by serum samples from experimentally infected rhesus monkeys, was identified from a Loa loa L3 cDNA library. IgG4 antibody reactivity to purified Ll-SXP-1 was assessed by means of ELISA, using serum samples from patients with loiasis, lymphatic filariasis, onchocerciasis, mansonellosis, or other helminthiases and healthy control subjects. The assay was 56% sensitive and 98% specific for loiasis. Antibody reactivity was detectable before microfilaremia in experimentally infected rhesus monkeys and declined (but did not disappear) after diethylcarbamazine therapy in infected patients. IgG4 antibodies to recombinant Ll-SXP-1 are a highly specific marker of L. loa infection and may be useful for the diagnostic evaluation of persons with filariasis of unclear etiology.