This is a phase I, double-blind, placebo controlled, parallel group, dose-escalating, randomised study designed to assess and compare the safety and tolerability, PK, and immunogenicity of GNbAC1 administered as a single dose at 4 different dose levels of 36, 60, 85 and 110 mg/kg.

Main Inclusion Criteria:

• Healthy male volunteers
• Negative urine drug screen
• Have signed the informed consent.

Main Exclusion Criteria:

• History of serious adverse reactions or hypersensitivity to any drug.
• Use of any prescription medication within 30 days prior to the administration of investigational product and/or non-prescription medication (including herbal and natural remedies, homeopathy, vitamins, and minerals) within 7 days prior to the administration of investigational product or anticipated use of any concomitant medication during the study. Permissible exceptions are paracetamol up to 4g/day ceasing a minimum of 12 hours prior to infusion and Ibuprofen up to 1.2g/day ceasing a minimum of 24 hours prior to infusion. Paracetamol and ibuprofen are allowed during the study, but only 24 hours after completion of the administration of investigational product.