Project description:BackgroundThe 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.MethodsWe 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.ResultsThe 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.ConclusionsThis 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; rVSV∆G-ZEBOV-GP ClinicalTrials.gov numbers, NCT02269423 and NCT02280408 .).
Project description:A recombinant S segment RNA (Sr) of the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) where the glycoprotein of vesicular stomatitis virus (VSVG) was substituted for the glycoprotein of LCMV (LCMV-GP) was produced intracellularly from cDNA under the control of a polymerase I promoter. Coexpression of the LCMV proteins NP and L allowed expression of VSVG from Sr. Infection of transfected cells with WT LCMV (LCMVwt) resulted in reassortment of the L segment of LCMVwt with the Sr at low frequency. Isolation of recombinant LCMV (rLCMV) expressing VSVG (rLCMV/VSVG) was achieved by selection against LCMVwt by using a cell line deficient in the cellular protease S1P. This approach was based on the finding that processing of LCMV-GP by S1P was required for virus infectivity. Characterization of protein and RNA expression of rLCMV/VSVG in infected cells confirmed the expected virus genome organization. rLCMV/VSVG caused syncytium formation in cultured cells and grew to approximately 100-fold lower titers than WT virus but, like the parent virus, it persisted in neonatally infected mice without clinical signs of disease.
Project description:Vesicular stomatitis virus (VSV) is a prototypic nonsegmented negative-strand RNA virus. VSV's broad cell tropism makes it a popular model virus for many basic research applications. In addition, a lack of preexisting human immunity against VSV, inherent oncotropism and other features make VSV a widely used platform for vaccine and oncolytic vectors. However, VSV's neurotropism that can result in viral encephalitis in experimental animals needs to be addressed for the use of the virus as a safe vector. Therefore, it is very important to understand the determinants of VSV tropism and develop strategies to alter it. VSV glycoprotein (G) and matrix (M) protein play major roles in its cell tropism. VSV G protein is responsible for VSV broad cell tropism and is often used for pseudotyping other viruses. VSV M affects cell tropism via evasion of antiviral responses, and M mutants can be used to limit cell tropism to cell types defective in interferon signaling. In addition, other VSV proteins and host proteins may function as determinants of VSV cell tropism. Various approaches have been successfully used to alter VSV tropism to benefit basic research and clinically relevant applications.
Project description:The devastating Ebola virus (EBOV) outbreak in West Africa in 2013-2016 has flagged the need for the timely development of vaccines for high-threat pathogens. To be better prepared for new epidemics, the WHO has compiled a list of priority pathogens that are likely to cause future outbreaks and for which R&D efforts are, therefore, paramount (R&D Blueprint: https://www.who.int/blueprint/priority-diseases/en/ ). To this end, the detailed characterization of vaccine platforms is needed. The vesicular stomatitis virus (VSV) has been established as a robust vaccine vector backbone for infectious diseases for well over a decade. The recent clinical trials testing the vaccine candidate VSV-EBOV against EBOV disease now have added a substantial amount of clinical data and suggest VSV to be an ideal vaccine vector candidate for outbreak pathogens. In this review, we discuss insights gained from the clinical VSV-EBOV vaccine trials as well as from animal studies investigating vaccine candidates for Blueprint pathogens.
Project description:Comparison of the transcriptiomic profile using microarray analysis betwween primary porcine macrophages infected with recombinant vesicular stomatitis viruses
Project description:Bundibugyo virus (BDBV) is the most recently discovered pathogenic species of ebolavirus, with mortality rates of 25% and 51% reported in two identified. BDBV infection is non-uniformly lethal in macaques. The lack of uniform lethality offers the opportunity for identification of biomarkers that correlate with positive and negative outcomes following infection that can help define mechanisms of pathogenesis and potentially serve as guides for clinical care. In both the treatment and control groups, ~58% survived infection, an increase over lethality seen in historical controls. There was no differential advantage of the BDBV GP expressing vaccine, suggesting a general effect of rVSV. Our transcriptomic analysis identified strong initial responses to infection and treatment in all animals. This response returned to baseline in animals with mild disease by day 7. In animals with severe disease, fatal cases could be predicted beginning at day 5 post infection based on the expression of 5 circulating mRNAs. This study suggested a nonspecific effect of treating NHPs with VSV-based vectors as a postexposure therapy following BDBV infection and identified potential biomarkers of outcome.
Project description:Emerging porcine epidemic diarrhea viruses (PEDVs) have caused large economic losses since 2010, and G2b is the prevalent globally epidemic genotype. Given the fastidious isolation of emerging PEDV in cell culture and difficulties in retaining the isolate infectivity upon further in vitro passage, highly attenuated recombinant vesicular stomatitis virus (rVSVMT) was used as a vector to express the PEDV spike (S) protein, aiming to develop a subunit vaccine against G2b viruses. An S protein with 19 of its cytoplasmic domain amino acids deleted could be incorporated into VSV particles, generating rVSVMT (VSVMT-SΔ19) with high efficiency. Our results suggest that VSVMT-SΔ19 could effectively induce PEDV-specific immunity in pigs via intramuscular, but not intranasal, immunization. Notably, immunizations of sows with VSV MT-SΔ19 provided protective lactogenic immunity against a virulent G2b PEDV challenge in piglets. Consequently, recombinant VSVMT may be a promising platform for preparing a subunit vaccine against PEDV.
Project description:The emergence of the novel henipavirus, Langya virus, received global attention after the virus sickened over three dozen people in China. There is heightened concern that henipaviruses, as respiratory pathogens, could spark another pandemic, most notably the deadly Nipah virus (NiV). NiV causes near-annual outbreaks in Bangladesh and India and induces a highly fatal respiratory disease and encephalitis in humans. No licensed countermeasures against this pathogen exist. An ideal NiV vaccine would confer both fast-acting and long-lived protection. Recently, we reported the generation of a recombinant vesicular stomatitis virus-based (rVSV-based) vaccine expressing the NiV glycoprotein (rVSV-ΔG-NiVBG) that protected 100% of nonhuman primates from NiV-associated lethality within a week. Here, to evaluate the durability of rVSV-ΔG-NiVBG, we vaccinated African green monkeys (AGMs) one year before challenge with an uniformly lethal dose of NiV. The rVSV-ΔG-NiVBG vaccine induced stable and robust humoral responses, whereas cellular responses were modest. All immunized AGMs (whether receiving a single dose or prime-boosted) survived with no detectable clinical signs or NiV replication. Transcriptomic analyses indicated that adaptive immune signatures correlated with vaccine-mediated protection. While vaccines for certain respiratory infections (e.g., COVID-19) have yet to provide durable protection, our results suggest that rVSV-ΔG-NiVBG elicits long-lasting immunity.