Passive Antibody
Using an approach that had proved successful with several other viral infections, researchers pursued a treatment/prevention approach that involved the passive transfer of antibodies to a mouse adapted Ebola virus into an infected host in order to clear the infection. Using a mouse model, these researchers successfully showed that an IgG antibody response was involved in mediating an Ebola infection.
In order to generate the serum that contained the anti-Ebola IgG antibody, mice were challenged subcutaneously with a small amount of the Ebola virus. It is important to note that in this animal model, the virus only proves fatal when injected into the peritoneal cavity. The exact reason for this is not understood, and this discrepancy when compared to the virus pathology in humans is something that needs to be considered. The mice were able to clear this infection, and when challenged again with a larger dose, mounted an aggressive response that was manifested in a high IgG antibody titer. This sera was collected, irradiated, and titrated by ELISA to obtain a highly pure IgG immunoserum.
This immunoserum was then administered to one group of mice one day before infection. The control group received a mock serum that contained no antibodies. The mice that received that IgG serum survived and cleared the infection with varying rates from 43% - 100%, while the control group mice all died by the eighth day of the experiment. This survival rate was correlated to the total amount of antibody serum that these mice received.
In a separate experiment, mice were given a high dose of the serum one day post-infection. The entire group that received the IgG serum survived.
These studies point to an important role for IgG in protecting against Ebola infection. These antibodies recognize the GP1 and sGP epitopes of the viral shell. The exact mechanism by which the virus is cleared is not exactly clear and warrants further investigation. One possible explanation is that the virus is cleared before there is any viral replication, as supported by some experimental evidence. However, other evidence points towards the antibodies slowing viral replication, and then recruiting some type of adaptive cellular response, the exact nature of which is not fully understood.
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This page last updated: 14 April 2004.
