Abstract: The present invention relates to methods exogenous nucleic acid molecules, such as RNA, that encode an antibody or antigen-binding fragment of an antibody, and optionally encode a cellular modulation factor and/or a potentiation factor. The cellular modulation factor is a factor that results in increased expression of the antibody and/or antigen-binding fragment. The potentiation factor is a factor that provides desired antibody effector or other properties. The exogenous nucleic acid molecules can be DNA or RNA, as mRNA (including self-replication RNA and non-self-replicating RNA). The invention also relates method for administering the exogenous nucleic acid molecules to a subject to achieve production of the encoded antibody or antigen-binding fragment in the subject to provide, for example, prophylactic or therapeutic passive immunity.