Antivirus software detects viruses and other malware (trojans, worms, etc). Anti virus applications protect your computer from unwanted activities. These applications should not catch OPC servers because the servers are not harming the computer. However, it is possible future automated updates may incorrectly flag your OPC applications.
Therefore, you should add your OPC clients and servers to the exception list so that they will not be accidentally stopped in the future.
Note: these anti-virus applications are only one part of a cyber security measures. To improve your protection, you should also deploy firewalls on each computer, and restrict user account access. For an automated solution, refer to OPC Rescue.