Thanks to Adam Whitehead who pointed this one out, the actress Natalie Victoria was informed that there were no more auditions for the role of Daenerys Targaryen because HBO has already filled the role. She adds that she was told HBO would not announce the actress who landed the role for a “few weeks”.
It should be noted that GRRM has stated that the role being cast would be news to him. This leaves several possibilities, such as an actress currently being negotiated with to take the part leading to the suspension of auditions for the time being, or that Ms. Victoria was misinformed.