Mac infected with virus

Malware is actually fairly rare on the Mac platform and true viruses don't exist on the Mac platform, as Terence said. If you think you've picked something up MalwareBytes is a trustworthy program that can be used free of charge. I run it once a month on my computers at work - found one adware last year that it removed without a hitch.

Uninstall Mackeeper using their uninstaller—it cause nothing but problems.

Finding false negatives is a way of upselling or getting you to buy this scamware.

If on the other hand you suspect you have installed adware/malware. Try running this trusted utility https://www.malwarebytes.com/mac/

You are being scammed. Uninstall MacKeeper.

It's not. None. There are no viruses in the wild that run on Macs. Is there a reason you think you may have contracted malware of some kind?