This study is to investigate the persistence of rabies Chinese manufactured antibody 1-5 years after the post-exposure prophylaxis with vero cell antirabies vaccine and antibody response to a single booster dose. A total of 160 subjects would be enrolled. These subjects were all administered ChengDa antirabies vaccine from 2005 to 2009. After informed consent is obtained, these subjects would be tested for their antirabies antibody titer and given a single booster dose. Seven and 14 days later, the investigators would re-evaluate the antibody titer.