Virgins? What Virgins? Really Virgins? Not Israelites? In any case I can explain that. I wrote before to you that dying or living people (of any gender) can be a symbol for a number of calendric days. I've encountered such before elsewhere and would not wonder if also the revelation uses such a language.
If there are Virgins, it resembles to the greek mythology, where the days of the half Octaeteris cycle have been described as the 50 "daughters" of Selena and Endymion. Now the Revelation is also actually a [i]greek[/i] piece of literature.