Ebolavirus Glycoprotein Fc Fusion Protein Protects Guinea Pigs against Lethal Challenge.
Ebola virus (EBOV), a member of the Filoviridae that can cause severe hemorrhagic fever in humans and nonhuman primates, poses a significant threat to the public health. Currently, there are no licensed vaccines or therapeutics to prevent and treat EBOV infection. Several vaccines based on the EBOV glycoprotein (GP) are under development, including vectored, virus-like particles, and protein-based subunit vaccines. We previously demonstrated that a subunit vaccine containing the extracellular domain of the Ebola ebolavirus (EBOV) GP fused to the Fc fragment of human IgG1 (EBOVgp-Fc) protected mice against EBOV lethal challenge. Here, we show that the EBOVgp-Fc vaccine formulated with QS-21, alum, or polyinosinic-polycytidylic acid-poly-L-lysine carboxymethylcellulose (poly-ICLC) adjuvants induced strong humoral immune responses in guinea pigs. The vaccinated animals developed anti-GP total antibody titers of approximately 105-106 and neutralizing antibody titers of approximately 103 as assessed by a BSL-2 neutralization assay based on vesicular stomatitis virus (VSV) pseudotypes. The poly-ICLC formulated EBOVgp-Fc vaccine protected all the guinea pigs against EBOV lethal challenge performed under BSL-4 conditions whereas the same vaccine formulated with QS-21 or alum only induced partial protection. Vaccination with a mucin-deleted EBOVgp-Fc construct formulated with QS-21 adjuvant did not have a significant effect in anti-GP antibody levels and protection against EBOV lethal challenge compared to the full-length GP construct. The bulk of the humoral response induced by the EBOVgp-Fc vaccine was directed against epitopes outside the EBOV mucin region. Our findings indicate that different adjuvants can eliciting varying levels of protection against lethal EBOV challenge in guinea pigs vaccinated with EBOVgp-Fc, and suggest that levels of total anti-GP antibodies elicit by protein-based GP subunit vaccines do not correlate with protection. Our data further support the development of Fc fusions of GP as a candidate vaccine for human use.
Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, United States of America.
Krishnamurthy
K
Konduru
United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, United States of America.
Amy C
AC
Shurtleff
United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, United States of America.
Steven B
SB
Bradfute
Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, United States of America.
Siham
S
Nakamura
United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, United States of America.
Sina
S
Bavari
Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, United States of America.
Gerardo
G
Kaplan
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000534:Alum Compounds / Q000008:administration & dosage; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D002266:Carboxymethylcellulose Sodium / Q000008:administration & dosage / Q000031:analogs & derivatives; D046129:Ebola Vaccines / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D029043:Ebolavirus / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D005260:Female; D006168:Guinea Pigs; D019142:Hemorrhagic Fever, Ebola / Q000276:immunology / Q000517:prevention & control*; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000276:immunology; D008297:Male; D011070:Poly I-C / Q000008:administration & dosage; D011107:Polylysine / Q000008:administration & dosage / Q000031:analogs & derivatives; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D012503:Saponins / Q000008:administration & dosage; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology*
D000276:Adjuvants, Immunologic; D000534:Alum Compounds; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D046129:Ebola Vaccines; D007141:Immunoglobulin Fc Fragments; D011993:Recombinant Fusion Proteins; D012503:Saponins; D014614:Vaccines, Synthetic; D014759:Viral Envelope Proteins; C113189:envelope glycoprotein, Ebola virus; D011107:Polylysine; C041524:aluminum sulfate; C078785:saponin QA-21V1; C019531:poly ICLC; D002266:Carboxymethylcellulose Sodium; D011070:Poly I-C