Properties of Light Particles Produced During Growth of Type 4 Adeno-Associated Satellite Virus

Adeno-associated satellite virus type 4, obtained by repeated undiluted passage, failed to produce distinct bands at the expected density of 1.43 g/cm³ after density gradient centrifugation in CsCl. This phenomenon occurred regardless of the hemagglutinating activity of the starting material. Sharp bands were found at a density of 1.34 to 1.35 g/cm³. These bands contained adenovirions and numerous satellite particles. These latter particles could be distinguished by electron microscopy from standard dense satellite particles by their flattened profiles and deep penetration of negative stains. Dense bands of satellite virus at 1.43 g/cm³ were constantly observed when the inoculum was comprised of highly diluted seed virus. Light satellite particles had a particle to HA ratio comparable with dense particles, but possessed low infectivity. Measurements of contour lengths of extracted deoxyribonucleic acid (DNA) indicate that light particles contain only a small amount of DNA, possibly less than 0.5 × 10⁶ daltons, compared to 1.4 × 10⁶ for the complete satellite DNA molecule.