SYMMETRICAL-STRAND PACKAGING OF RECOMBINANT PARVOVIRUS LUIII GENOMES THAT RETAIN ONLY THE TERMINAL REGIONS

LuIII is an autonomous parvovirus which encapsidates either strand of its genome with similar efficiency in NB324K cells. Two parvoviruses c losely related to LuIII, minute virus of mice (MVM) and H-1 virus, enc apsidate primarily the minus strand of their genome when grown in the same cell type. It has been postulated that an AT-rich region unique t o LuIII is responsible for symmetric encapsidation of plus- and minus- strand genomes by LuIII. To address this hypothesis, recombinant LuIII -luciferase genomes containing or lacking the AT-rich sequence (AT) we re packaged into LuIII virions. Hybridization of strand-specific probe s to DNA from these virions revealed that either strand of the genome was packaged regardless of the presence of AT. In addition, encapsidat ion of both strands of the AT(+) LuIII-luciferase genome into MVM and H-1 virions mas observed, suggesting that MVM and H-1 viral proteins a re not responsible for the minus-strand packaging bias of these two vi ruses. Alignment of the published LuIII and MVMp sequences shows that AT exists as an insertion into an element that, in MVM, binds cellular proteins. We suggest that in LuIII, AT disrupts binding of these cell ular proteins, allowing encapsidation of either strand.