Recombinant proteins of Zaire ebolavirus induce potent humoral and cellular immune responses and protect against live virus infection in mice

Abstract

Infections with filoviruses in humans are highly virulent, causing hemorrhagic fevers which result in up to 90% mortality. In addition to natural infections, the ability to use these viruses as bioterrorist weapons is of significant concern. Currently, there are no licensed vaccines or therapeutics available to combat these infections. The pathogenesis of disease involves the dysregulation of the host's immune system, which results in impairment of the innate and adaptive immune responses, with subsequent development of lymphopenia, thrombocytopenia, hemorrhage, and death. Questions remain with regard to the few survivors of infection, who manage to mount an effective adaptive immune response. These questions concern the humoral and cellular components of this response, and whether such a response can be elicited by an appropriate prophylactic vaccine. The data reported herein describe the production and evaluation of a recombinant subunit Ebola virus vaccine candidate consisting of insect cell expressed Zaire ebolavirus (EBOV) surface glycoprotein (GP) and the matrix proteins VP24 and VP40. The recombinant subunit proteins are shown to be highly immunogenic in mice, yielding both humoral and cellular responses, as well as highly efficacious, providing up to 100% protection against a lethal challenge with live virus. These results demonstrate proof of concept for such a recombinant non-replicating vaccine candidate in the mouse model of EBOV which helps to elucidate immune correlates of protection and warrants further development.

Ebola Virus Glycoprotein Induces an Innate Immune Response In vivo via TLR4

“…Mouse models have proven to be useful tools to understand immune responses to filovirus infection and evaluate vaccines and antiviral compounds (Bradfute et al, 2012 ). Our previous study used a mouse model to evaluate the potential of recombinant EBOV proteins expressed in stably transformed Drosophila S2 cell lines to protect against EBOV infection (Lehrer et al, 2017 ). We demonstrated that while 3 doses of purified recombinant EBOV GP along with adjuvant completely protected mice challenged with 100 PFU of mouse adapted EBOV, mice immunized with GP alone showed partial protection, with survival of 7 of 10 mice following lethal challenge (Lehrer et al, 2017 ).…”

“…Our previous study used a mouse model to evaluate the potential of recombinant EBOV proteins expressed in stably transformed Drosophila S2 cell lines to protect against EBOV infection (Lehrer et al, 2017 ). We demonstrated that while 3 doses of purified recombinant EBOV GP along with adjuvant completely protected mice challenged with 100 PFU of mouse adapted EBOV, mice immunized with GP alone showed partial protection, with survival of 7 of 10 mice following lethal challenge (Lehrer et al, 2017 ). To further understand the association between protection and antibody response to EBOV GP alone and GP + adjuvant, we evaluated the kinetics of GP-specific IgG antibodies in BALB/c mice immunized with 10 μg of GP or GP + adjuvant via the subcutaneous route, followed by two booster doses at 4 week intervals post primary immunizations.…”

“…Recombinant EBOV GP was produced from insect cells and purified using immunoaffinity chromatography following previously published methods (Lehrer et al, 2017 ). To further increase the level of purity, protein used for our studies was subjected to an additional purification step via size-exclusion chromatography using a HiLoad 16/600 Superdex 200 prep grade column (GE Healthcare Life Sciences, Piscataway, NJ) equilibrated in phosphate buffered saline, pH7.4 (Figure 1A ).…”

A Novel Bacterium-Like Particle-Based Vaccine Displaying the SUDV Glycoprotein Induces Potent Humoral and Cellular Immune Responses in Mice

“…Currently, most EBOV vaccines target the viral GP antigen. Notably, previous studies have shown that subunit vaccines based on eGP were able to protect vaccinated mice against lethal EBOV challenge [29,30]. Bazzill, J. D. et al [31] proved that a recombinant EBOV antigen (eGP) incorporated into lipid-based nanoparticles could efficiently generate germinal center B cells and polyfunctional T cells while eliciting robust neutralizing antibody responses.…”

Filovirus – Auslöser von hämorrhagischem Fieber

“…Eine Kombination rekombinanter Antigene aus GP, VP24 und VP40, zur Immunisierung intramuskulär verabreicht, schützte Mäuse zu 100 % vor einer tödlichen EBOV-Infektionsdosis [177].…”