Taken only once? Where do you see that in the article?
It's not in the article - as I said in an earlier post, I went to a Q&A with one of the scientists involved in the research.
If this works, they will use gene therapy to alter a person's genes so that their own body produces the protein that prevents HIV developing into AIDS. That's a complicated treatment but it's a one off treatment. Similar treatments are already in use for a few other diseases, but they are complicated, which is one reason why there are still questions as to whether or not this will pan out as a successful treatment.