Study of UB-312 in Healthy Participants and Parkinson's Disease Patients

Inclusion Criteria: * Male or female aged 40 to 85 years old, inclusive at screening * Expected to be able to undergo all study procedures * Other inclusion criteria apply For Part B only: * A diagnosis of PD, confirmed by a neurologist * Hoehn \&Yahr Stage ≤ III at Screening * Stable treatment of permitted antiparkinsonian medications from 30 days prior to first study drug administration or 60 days for MAO-B inhibitors, and expected to remain stable throughout the study Exclusion Criteria: * Clinically significant abnormalities, as judged by the investigator * History of medical, neurological or psychiatric conditions which in the opinion of the investigator may compromise participant's safety or scientific value of the study * Acute or chronic infection as judged by the investigator, for positive human immunodeficiency virus (HIV), hepatitis C virus (HCV) or hepatitis B virus (HBV) * History or evidence of an autoimmune disorder * History of anergy. * Participated/participating in any clinical trial with monoclonal antibodies or vaccines directed at aSyn * Other exclusion criteria apply For Part B only: * Other known or suspected cause of Parkinsonism other than idiopathic PD * History or evidence at Screening of PD-related freezing episodes, falls, or orthostatic hypotension * Dopamine transporter single-photon emission computerized tomography scan (DaTscan) inconsistent with dopamine transporter deficit. * Clinically significant neurological disease other than PD