Provided herein are helper nucleic acids comprising at least one microRNA target sequence of an endogenous, cellular microRNA and a nucleic acid encoding a viral protein, wherein the microRNA target sequence is located in the untranslated or translated region of the nucleic acid encoding the viral protein. Also provided are vector systems, compositions and cells comprising the provided helper nucleic acids and a vector or replicon. Methods of making virus-like replicon particles and populations of virus-like replicon particles (VRP) are also provided.