There are many interconnecting parts to the immune system. The review of several US patents regarding filoviruses (particularly Marburg and Ebola-Zaire) revealed how the virus attaches to host cells, and how to decrease that attachment.
The Death of Your Cells
Ebola Zaire gets into the blood and activates the endothelial cells. They control what goes in and out of the blood stream, what materials get transmitted. Once activated, they release nitric oxide “which triggers apoptosis of thymocytes.” This is the self-destruction of your immature white blood cells. 
The activation of endothelial cells is also the suspected cause of white blood cell (lymphocytes) death. An increase in the death of these mature white blood cells was observed as early as three days post infection. 
How Ebola Gets in
Once the virus is in your cells replicating and the immune system is destroyed, there is little chance of recovery. So the main question is how to keep the virus out of your cells. US patent numbers 6933108 and 7803555 are the key to that answer.
The Ebola-Zaire virus attaches to any cell surface with a folate receptor. Once attached, the virus then enters the cell. 
Folic Acid inhibits this binding. [2, 3]
To clarify, taking folic acid will not prevent infection of the Ebola virus, but it will reduce the viruses binding and entry into your cells. 
In these experiments “agents include those that inhibit filovirus binding to a folate receptor on the cell surface, agents that reduce the level of folate receptor on the cell surface, and agents that modulate the folate receptor such that binding of a filovirus to the folate receptor is reduced.”
This clearly defines an ‘agent’ as something which keeps Ebola from attaching to your cell, thus keeping it from replicating.
“Methods of Treating a filovirus-Mediated Disease Condition … generally comprise administering to an individual an effective amount of an agent that reduces a level of folate receptor-mediated viral entry into a cell in the individual.”
So you want to give an individual enough of an ‘agent’ to fill enough of the folate receptors that a reduction in Ebola virus binding is decreased. It’s just like taking the right dose of medicine. No specific amount of folic acid was discussed.
“It has further been shown that filovirus entry into a susceptible cell can be inhibited by inhibiting binding of a filovirus to a FR on the surface of a susceptible cell. Accordingly, in some embodiments, a method of treating a filovirus-mediated disease condition in an individual comprises administering to an individual an effective amount of a substance that inhibits binding of a filovirus to a FR on the surface of a susceptible cell in the individual. As used herein, the term “agent” refers to any substance that inhibits binding of a filovirus to FR, including, but not limited to, antibody specific for FR; folic acid and its derivatives; and soluble FR. Generally, these methods involve blocking a binding event between a filovirus and an FR.”
FR stands for folate receptor.
“FR is a protein encoded by a gene that is a member of the folate receptor family. Members of this gene family have a high affinity for folic acid and for several reduced folic acid derivatives, and mediate delivery of 5-methyltetrahydrofolate to the interior of eukaryotic cells.”
“MBG virus entry was reduced by nearly 80% in the presence of folic acid.” 
This is important to acknowledge because Marburg (MBG) and Ebola are both filoviruses.
“In the presence of folic acid, entry by EBO-Z virus was inhibited significantly.” 
The specific percentage was not noted for Ebola-Zaire (EBO-Z).
At the time of writing this, there are no known vaccines or cures for any filovirus. But more than one scientific study confirms that folic acid does reduce the binding of Marburg and Ebola-Zaire. And it gives your immune system a fighting chance.
The research did not differentiate between folic acid and folate which occurs naturally, but their differences should be noted.
Keep in mind that during a pandemic, it is important to keep folic acid levels stable and to have enough on hand at the time you become infected. Eating leafy vegetables is a good way to stabilize levels now. Folic acid is found naturally in beans, making them a good food to stock up on.
 US Patent #6933108
 US Patent #7803555
7803555 appears to be the updated version of 6933108. Two corrections have been made to the original patent 6933108 and are noted and viewable under images in 7803555. Any and all quotes not referenced above are found in these two patents.
The research paper can be found at www.cell.com