I thought once you had ebola you were immune from catching it again.
Previously known sources of ebola infection : personal contact or proximity with infected person, or their property,
consumption of infected 'wild meats', sexual intimacy with an infected individual.
Even those who survive the disease face 'shunning' and social distancing from others; so obviously there is a concern in their society of infection.
Specifically trying to answer your question about being immune, I don't recall that as being the case.
We are still learning more each day about the intricacies and specifics of viral infections and diseases.