Patent ID: 7008791

Claim:
Method of eliciting an IgA response in a mammal comprising administering orally to the mammal a composition comprising a nucleic acid operatively encoding an antigen complexed with or entrapped within liposomes formed from liposome forming components comprising a) at least one cationic compound b) zwitterionic phospholipid consisting of one or two compounds having the general formula II in which R 3 and R 4 are the same or different and are a group of the formula CH 3 (CH 2 ) e (CH═CH—H 2 ) f (CH 2 ) g — in which f is 0 to 6, each of e and g+3f are 0 to 23 and e+g is in the range 12 to 23; R 7 is a C 1-8 alkanediyl group; Y is —O— or a bond; X 2 is N, P or S; m is 3 when X 2 is N or P and is 2 when X 2 is S; and the groups R 8 are the same or different and are selected from the group consisting of hydrogen, C 1-8 alkyl, C 6-11 aryl or aralkyl, or two or three of the groups R 8 together with X 2 form a saturated or unsaturated heterocyclic group having 5 to 7 ring atoms; in which at least 25% by mole of the individual liposome forming components have a transition temperature of more than 40° C., wherein the molar ratio of cationic compound to zwitterionic phospholipid is in the range 1:1 to 1:10, whereby an IgA response to the said antigen is generated.