immunization in both VO and OBI

[zhengj2007]

VO immunization: immunization is a processual entity that primes or modifies an adaptivie immune response to some antigens. OBI immunization: The process of an epitope that is part of or derived from an immunogen coming into contact with adaptive immune cells resulting in these cells acquiring immune effector functions specific for the epitope.

Need to discuss with OBI developer to merge the terms.