Fish Immunology (1+1)

Unit 15 - Adjuvants

15.1. Introduction

The term adjuvant has been derived from a Latin word adjuvare, which means to help, thus any material that enhances the immunity is referred as adjuvant. An adjuvant by definition is a substance, Adjuvants are diverse range of substances those modulate/enhance the immune response when used in combination with antigen. Addition of adjuvants helps in lowering the dosage of vaccine given, efficient absorption and slower processing of antigen, application of vaccine at low temperature and reduction of side-effects of antigenic preparations. The use of adjuvant is quite common in human and veterinary medicine and goes together with the concept of immunization/ vaccination and has gradually been shifted to aquaculture.
Adjuvants can act as immunostimulators, immunomodulators and immunopotentiators. They can either be administered in combination with or before or after the immunization while some of them can also be given alone. Those are given along with the antigen are FCA, FIA, MDP, polynucleotides, aluminium salts, endotoxins etc. Some of them are immunostimulants and given after the antigen administration, they include glucan and others, however, if given before, they cause immune tolerance. Some are given as immunopotentiators to restore the depressed immunity and others are either given alone or prior to antigenic stimulation. These include levamisole, BCG, dextran sulphate, etc.