Years ago, I published a paper with some collaborators, and recently a comment to the paper has been submitted. Together with the other authors, we published a reply to comment, which has been published on the journal.
Is it reasonable to list the reply as a publication in my CV, in addition to the original paper?
Yes, but you would probably want to make separate lists of refereed and non-refereed publications. By putting the comment in the latter list, you do show that you engage with academic discussion, but you do not overclaim it as yet another refereed publication.
Generally you can put whatever you like in your CV. And generally the reader will judge whether it is a real thing or padding. If the reply is truly substantive then it might be worth including it (along with links to the comment you are replying to) so that a reader gets a more complete picture of the current state of the original publication. But I would, personally, probably want to set it off as a "comment" and not as a "publication".
It is a subtle thing, though, and it requires judgement. Your judgement.
I'd expand the entry, in my publication list, for the original paper by appending a reference to the reply. So the entry would look like: "List of authors, "Title of Paper", journal, volume (year), pages. See also "Title of reply", ibid., volume (year), pages."
My publication list is divided into sections, which in your case could look something like this (add/delete as appropriate)
Journal papers
Peer reviewed conference papers
Peer reviewed short comment
Non-peer reviewed conference abstracts
The section with the comment in it would list only one publication, but that's ok.
I generally put "peer reviewed" or "non-peer reviewed" in the section titles, because (for example) in some fields conference publications would not usually be peer reviewed whereas in others they are, so I think it helps to make it clear.
Another option is just to put a brief explanation after the reference in your publication list, e.g. "Peer-reviewed reply to comment"
Like you said, it is refereed. So it must be an academic publication. The ambiguity left is how much it counts for.
Well, it really depends on institutions and countries. Many top departments in top countries (like USA) will heavily discount those reply and comments; however, keep in mind that those department evaluation your contribution by reading instead of counting.
Lesser departments count more, and count comments for more.
