Parkinson's disease (PD) is characterized as a neurodegenerative movement 
disorder presenting with rigidity, resting tremor, disturbances in balance and 
slowness in movement. An important pathologic feature of PD is the presence of 
Lewy bodies. The primary structural component of Lewy bodies are fibrils 
composed primarily of alpha-synuclein, a highly conserved 140 amino acid protein 
that is predominantly expressed in neurons and which may play a role in synaptic 
plasticity and neurotransmission. Numerous studies suggest the aggregation and 
modification of alpha-synuclein as a key step leading to Lewy body formation and 
neuronal cell loss associated with PD. Because of the central role of 
alpha-synuclein in PD, it represents a novel drug target for the possible 
treatment of this disease. In this review, an overview of the role of 
alpha-synuclein in PD will be discussed with an emphasis on recent studies 
utilizing an immunization approach against alpha-synuclein as a possible 
treatment option for this debilitating disease.