Comparison of dimethyl dioctadecyl ammonium bromide, Freund's complete adjuvant and mineral oil for induction of humoral antibodies, cellular immunity and resistance to Newcastle disease virus in chickens.

Dimethyl dioctadecyl ammonium bromide (DDA), a lipophilic quaternary amine, was evaluated in adult chickens for potentiation of immunological responses to subcutaneously administered inactivated Newcastle disease virus (NDV) vaccines. DDA enhanced humoral and cell-mediated immune (CMI) responses to levels which were significantly higher than those induced by the vaccine alone The haemagglutination inhibition antibody titers induced by DDA were slightly lower than those induced by mineral oil although neutralizing antibody titers seemed to be higher. DDA induced strong CMI (DTH and lymphocyte proliferation) responses, more than those induced by Freund's complete adjuvant and mineral oil. Both DDA and mineral oil induced comparable high levels of protection to challenge doses of 200,000 LD50 per chicken. No toxic effects or local tissue damage were observed in any of the inoculated chickens.