The present invention relates to a viral particle. The viral particle has a radius of less than about 1 μm, and at least one peptide comprising at least a biologically active portion of CD47. The present invention also includes a method of increasing the life of a particle in vivo in a mammal. The method includes the steps of expressing at least one peptide comprising at least a biologically active portion of CD47 in a viral particle, and administering the viral particle having CD47 expressed to a mammal, wherein the administered viral particle has a longer half life in the mammal than an otherwise identical viral particle that does not have CD47 expressed thereon.
