Antibody responses to a related series of highly glycosylated Ebola virus proteins

The Ebola virus (EBOV) is a dangerous pathogen due to its high mortality rate (up to 90% in some outbreaks). The virus is largely confined to local regions in sub-Saharan Africa. However, if it should be artificially spread through increased urbanization and global travel, not to mention biowarfare and bioterrorism, it could pose a serious worldwide health threat. Research into the prevention and treatment of EBOV infection is therefore valuable. Several studies have indicated that immune responses against the EBOV glycoprotein (GP) are important for protective immunity. This line of research is aimed at understanding antibody responses to EBOV GP, and applying this knowledge to vaccine design and improvement.; The neutralizing antibody KZ52 has been proven to be effective in protecting guinea pigs from challenge with EBOV. However, the study documented here, conducted in a primate model, which more closely mirrors humans, indicated that KZ52 was unable to protect the macaques. This underscores the importance of the cellular branch of the immune system in rapid response to EBOV infection, such as those induced in successful vaccine studies.; The envelope glycoprotein of EBOV is produced in several different forms during infection: secreted glycoprotein (sGP, transcribed ∼80% of the time), glycoprotein (GP, created by a frameshift in the GP gene, made up of GP1 and GP2) transcribed 20% of the time, and soluble glycoprotein 1 (GP1, the N-terminal domain of GP). Two mutants were created, GPdTM (transmembrane-deleted Ebola glycoprotein) and the mucin-like domain (a heavily N- and O-glycosylated domain which may mask the protein from immune detection) deleted GPdTMdmuc. To begin to attain an understanding of antibody responses against GP, both natural variants and mutants of GP were cloned for soluble expression. These proteins were used in relative immunogenicity and antigenicity studies. It was found that sGP, though a potent cross-reactive antigen, was able to elicit neutralizing antibodies and therefore would not be the optimal decoy it was once proposed to be. GPdTM was not efficient at eliciting high binding nor neutralizing titers. Purified monoclonal antibodies produced from splenocyte hybridomas will be the focus of future studies on elucidating the role of antibodies in infection, based on specific interactions with the Ebola virus glycoprotein.