To assess the safety and immunogenicity of extended treatment with DAC HYP. This evaluation will include the following major components: • An assessment of safety and immunogenicity of extended treatment with DAC HYP when administered to MS subjects who have completed 52 weeks of active therapy with DAC HYP in Study 205MS201. • An assessment of safety and immunogenicity during a 6-month washout period from DAC HYP. • An assessment of safety and immunogenicity during re-initiation of therapy with DAC HYP after a 6-month washout period. • An assessment of safety and immunogenicity of DAC HYP when administered to MS subjects who previously received placebo during study 205MS201 Note: The 6-month washout period is defined by the 24-week period between the last scheduled administration of DAC HYP at the Week 48 visit in 205MS201 and the re-initiation of DAC HYP at the Week 20 visit in 205MS202.