New Dag member anti-virus / malware conciderations

hello. just a quick question.

I am building a 2nd CAS and MBX server for my environment to provide some redundancy in a DAG, our production exchange server runs on ESET exchange anti-virus and the inbuilt malware / virus protection is disabled.

a thought I had was, what anti-virus / malware must the DAG mbx/cas servers have on them, i guess they would only be of concern if they became active. 

just wanted to know what the best practice would be.

many thanks 

BpdZenith Ltd