Q: In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.
 The authors recommend in cases with an elevated transaminase serum activity more frequent check - up examinations to avoid missing of a relapse , and to examine repeatedly IgM anti - HAV as in protracted forms of hepatitis IgM anti - HAV may persist even when the transaminase activity is normal .
A:
anti - HAV