Department of Biology, Virginia Polytechnic Institute, Blacksburg 24061.
Parvovirus LuIII encapsidates single-stranded DNA of either plus or minus polarity with equal frequency, whereas the rodent parvoviruses MVMp and H-1 encapsidate minus strand DNA only. A full-length, infectious clone of LuIII was constructed and the complete nucleotide sequence of the genome was determined. Comparison of the LuIII sequence with those of MVMp and H-1 revealed that these viruses are virtually identical with respect to the genomic organization, location of regulatory signals, mRNA splicing patterns, and amino acid sequences of viral proteins. However, two regions of the LuIII sequence differ significantly from those of the rodent parvoviruses. At mu 92, LuIII has only one copy of a sequence found as a direct repeat in MVMp and H-1. Upstream of this sequence, at mu 89, there is an A-T-rich region, 47 nucleotides in length, unique to the LuIII genome. This A-T-rich region could represent a signal responsible for the totally different encapsidation patterns observed for these viruses.