Which programming language is professionally used for making virus

Answer 1

"making" a virus does not rely on the programming language it is coded in, but the source code itself in any language does. You can code in Python, C++, PHP etc.
All depends in the objective of your code. Also, a virus can be anything malicious but you need to specify its type as well (Trojan, Worm, Rogue); any sort of malware, adware etc. really.

Keep in mind that this follows a further route than just coding, so if you're into malware development what not, there are resources specifically based on that field.

Answer 2

what does "professionally" in this kind of context mean? :-D