That is part of the problem, the virus software.
You may not be aware of it but there are no virus' for the Mac at this time.
I have used Macs since 1989 and have never used anti virus for anything, I have never had a virus, spyware or malware.
Turn that off, so that it does not interfere, it may be it caused this issue to begin with.
They may be so corrupted now that they be beyond recovery. I would totally disable the anti virus in all its forms and try rebuilding again or use Data Rescue, you should then be able to recover the original photos, that is your best hope at this point. When I say originals that is what they are, iPhoto keeps an unaltered version of every photo untouched.
It makes a copy and that is what you see when iPhoto is opened.
I wish I had known about the anti virus before and I should have asked, I don't use any and so don't think about others using it.
I will remember that lesson in the future.