Mechanism of Human Antibody-Mediated Neutralization of Marburg Virus

Abstract

Summary The mechanisms by which neutralizing antibodies inhibit Marburg virus (MARV) are not known. We isolated a panel of neutralizing antibodies from a human MARV survivor that bind to MARV glycoprotein (GP) and compete for binding to a single major antigenic site. Remarkably, several of the antibodies also bind to Ebola virus (EBOV) GP. Single-particle EM structures of Antibody-GP complexes reveals that all of the neutralizing antibodies bind to MARV GP at or near the predicted region of the receptor-binding site. The presence of the glycan cap or mucin-like domain blocks binding of neutralizing antibodies to EBOV GP but not to MARV GP. The data suggest that MARV neutralizing antibodies inhibit virus by binding to infectious virions at the exposed MARV receptor-binding site, revealing a mechanism of filovirus inhibition.

Broadly neutralizing antibodies with few somatic mutations and hepatitis C virus clearance

“…Human hybridomas were generated as described previously (39). In brief, cryopreserved PBMC samples from subjects 110 and 117 were transformed with EBV, CpG, and additional supplements.…”

“…Cells from wells with supernatants reacting with HCV antigens were fused with HMMA2.5 myeloma cells using an electrofusion technique (40). After fusion, hybridoma cell lines were cloned by limited dilutions and single-cell fluorescence-activated cell sorting and expanded in post-fusion medium as previously described (39). HiTrap Protein G or HiTrap MabSelectSure columns were used to purify HCV-specific antibodies from filtered cell culture supernatants.…”

“…Total cellular RNA was extracted from clonal hybridomas that produced HCV antibodies, and RT-PCR reaction was performed using mixtures of primers designed to amplify all heavy chain or light chain antibody variable regions. Antibody variable gene sequence analysis was performed as previously described (39). Heavy and light chain antibody variable region sequences were analyzed using the IMGT/V-Quest program (51,52).…”

Generation and characterization of protective antibodies to Marburg virus

“…Standard mouse models, using C57BL/6 or BALB/c, could only be utilized with a mouse-adapted Ravn 17,20 or mouse-adapted Ci67 18 , as previously done by others. These antibodies bind to Ci67 with some cross reactivity to Angola or Musoke, but are not cross reactive to Ravn.…”

“…administration of a 100 mg of antibody, with multi-dose regimen beginning 24-hr pre-exposure followed by 24 hr post-exposure against 1000 PFU mouse-adapted Ci67 strain. 18 The mAbs described in our studies were assessed in both male and female groups of mice with no efficacy differences observed between sexes. In addition to the baseline protection study, we re-challenged our mice thirty-five days after the initial exposure.…”