Different parts of the host defense system work together to eliminate invading bacteria. Give some examples of how virulence factors could work together to make a pathogen better able to cause...

Different parts of the host defense system work together to eliminate invading bacteria. Give some examples of how virulence factors could work together to make a pathogen better able to cause infection.

It was stated in the text that virulence factors might have arisen long before animals appeared on Earth. Of course, this is just speculation, but what arguments could be made to support this statement?