This disease continues to be a challenge to human health In particular, the Zaire Ebola virus (ZEBOV) is the most aggressive serotype and has the highest mortality rates. Clinical trials have shown the efficacy of several vaccines, among them a vectored vaccine based on chimpanzee adenovirus and a vesicular stomatitis virus (VSV) chimeric vaccine.
Ebola virus is an enveloped filamentous negative-stranded RNA virus formed by seven structural proteins . The three most abundant structural proteins are VP40, the Ebola virus glycoprotein GP, and the nucleoprotein (NP); with a content of each protein in the capsid of approximately 37.7%, 4.7% and 17%, for VP40, GP and NP, respectively.
Filovirus particles have a uniform diameter of 80 nm and variable lengths. A single transmembrane glycoprotein (GP), consisting of two subunits, GP1 and -2, is inserted into the virus envelope as a trimeric complex. GP mediates cell attachment and endocytosis by binding to attachment proteins of the host cell. Thereby unmasking a binding site for the host factor Niemann-Pick C1 (NPC1). This cholesterol transport protein has been shown to be an essential host factor and endosomal entry receptor for filoviruses.
Increased efforts have been focused towards the development of interventions. Several vaccine candidates against Ebola virus have been produced based on different recombinant vaccine platforms including DNA, recombinant proteins, virus-like particles, and replicating and non-replicating viral vectors. Most express the viral glycoprotein as the main immunogen. Some of these candidates have been evaluated in clinical trials, including those based upon recombinant adenoviruses and recombinant vesicular stomatitis virus.
Studies of candidate vaccines have also indicated that the humoral arm of the immune system plays a pivotal role in protection. The efficacy of experimental EBOV vaccines in NHP challenge models most frequently correlate with the presence of anti-EBOV IgG detected by ELISA prior to challenge including the leading vaccine candidate based on a recombinant vesicular stomatitis virus vector.
Virology: Current research