Right from the Monster Manual

"Vampire Characters
Vampires are always evil, which causes characters of certain
classes to lose some class abilities, as noted in Chapter 3 of the
Player ’s Handbook. In addition, certain classes take additional
penalties.

Clerics: Vampire clerics lose their ability to turn undead but
gain the ability to rebuke undead. This ability does not affect the
vampire’s controller or any other vampires that a master controls.
A vampire cleric has access to two of the following domains:
Chaos, Destruction, Evil, or Trickery.

Sorcerers and Wizards: Vampire sorcerers and wizards retain
their class abilities, but if a character has a familiar other than a rat
or bat, the link between them is broken, and the familiar shuns its
former companion. The character can summon another familiar,
but it must be a rat or bat."

It seems you turn evil, trade turn for rebuke, and lose your domains.

In addition to being the eternal servant of the vampire who made you...