1. A liposome in which an RNA encoding an immunogen of interest is encapsulated, and wherein said liposome has a diameter in the range of 60-180 nm. 2. The liposome according to claim 1, wherein said liposome has a diameter in the range of 80-160 nm. The liposome according to claim 1, where the specified liposome contains a lipid with a cationic end group. The liposome according to claim 1, wherein said liposome contains a lipid with a zwitterionic end group. The liposome according to claim 1, where the RNA is self-replicating RNA. The liposome of claim 5, wherein the self-replicating RNA encodes (i) an RNA-dependent RNA polymerase that can transcribe RNA from self-replicating RNA, and (ii) an immunogen. The liposome of claim 6, wherein the self-replicating RNA contains two open reading frames, the first of which encodes an alphavirus replicase and the second of which encodes an immunogen. The liposome according to claim 5, where the length of the self-replicating RNA is 9000-12000 nucleotides. The liposome of claim 1, wherein the immunogen can elicit an in vivo immune response against a bacterium, virus, fungus, or parasite. A pharmaceutical composition comprising a liposome according to any one of the preceding claims. A pharmaceutical composition comprising a population of liposomes, where the average diameter of the liposomes in said population is between 60 nm and 180 nm inclusive. A method for generating a protective immune response in vertebrates, comprising the step of administering to the spinal column an effective amount of liposome according to any one of claims. 1-9, or the pharmaceutical composition of claim 10 or 11.13. The liposome of claim 2, wherein said liposome contains a lipid with a cationic end group. The liposome of claim 2, wherein said liposome contains a lipid with a zwitterionic end group.1. Липосома, в которой РНК, кодирующая представляющий интерес иммуноген, инкапсулирована, и где указанная липосома имеет диаметр в интервале значений 60-
