Actually the movie is based on the more traditional story of
VAN HELSING(note that there is only one "L" in Helsing) who at the time was the renouned Vampire Hunter in Bram Stoker's
Dracula. If anything, Bram's character is the original Helsing, in which anime's like Hellsing and Vampire Hunter D were based upon.
The wolfman was part of Stoker's concept of having "animal men" as personal assistants or servants of Dracula. So it gave rise to many stories of lycanthrops as either slaves of vampires or their bitter enemies (Thus the roleplaying game from White Wolf's
Werewolf: The Apocalypse and
Vampire: The Masquerade came into being-- and of course, the movie
Underworld).
As for the
manananggal part, well, i guess every movie producer likes a good catchy movie monster instead of the old traditional bat-man (which, btw, in the movie "Bram Stoker's Dracula" was superbly scary- to me perhaps). --;
For more Bram Stoker's Van Helsing sources check out these links:
The Journal of Van HelsingDracula the Undead: An extract from the novelCheck out the official
Van Helsing the movieAdded note: I havent seen the movie yet, but i think the woman you saw in the trailer would probably be Miss Harker, Van Helsing's partner in tracking down Dracula. It's the same woman you saw in the movie The League of Extraordinary Gentlemen, who was at the time, a vampire.
Yowzer!
B)