vaccine component and role

[zhengj2007]

vaccine component
defined as 'material entity' and ('part of' some vaccine)

vaccine component role defined as 'a role that inheres in a material entity that becomes an ingredient of a vaccine' with
axiom: 'characteristic of' some ('part of' some vaccine)

So, does vaccine component has role [vaccine component role]?

There also some roles seem associated with some 'vaccine component' such as 'vaccine antigen role', 'vaccine antigen' (defined as: 'vaccine component' and ('has role' some 'antigen role').

So, do we need these roles? If we need, shall we associated the role with the material entity?