The termini of the autonomous parvovirus LuIII, which encapsulates plus and minus DNA strands equally, were cloned and sequenced. The left and right termini of LuIII differ in nucleotide sequence and these termini can assume T- and U-shaped intra-strand base-paired structures, respectively. The LuIII termini are virtually identical in nucleotide sequence and secondary structure to those of the rodent parvoviruses MVM and H-1. The presence of non-identical LuIII termini demonstrated that identical ends are not required for the encapsidation of both DNA strands with equal frequency, as suggested for parvoviruses B19 and AAV. An infectious genomic clone of LuIII was constructed and sequenced. The LuIII genome is 5135 bases and it shares over 80% sequence identity with the sequence of the genomes of MVM and H-1. The genome organization of LuIII is virtually identical to that of the rodent parvoviruses of known sequence. The major ORFs, the left and right ORFs, are restricted to the plus strand. Promoter-like sequences are present at map units 4 and 38. The transactivation responsive element (TAR), characterized in H-1, upstream of P38, is also present in LuIII. Regulatory sequences and splice donor-acceptor consensus sequences, characterized in MVM and H-1, are also present in LuIII. This suggests that both LuIII promoters are functional, and that the transcription map for LuIII could be very similar to that of MVM. The LuIII sequence has only a single copy of a repeat present in tandem at the right end of the MVMp genome. Downstream of this sequence, an A-T rich region of 47 nt is present in LuIII. Since this A-T rich region is absent from the genomes of MVM and H-1, we propose that it represents a putative encapsidation signal responsible for the encapsidation pattern observed for LuIII. Northern analysis of BPV RNAs suggests that, like the human parvovirus B19, most, if not all, BPV transcripts initiate at promoter sequences localized at map unit 4. Amplification of BPV cDNA ends by the polymerase chain reaction resulted in a number of BPV-specific fragments. Four of these fragments were cloned and sequenced. Sequencing revealed two splices, one of which is very likely a major splice for several BPV transcripts. cDNA fragments were assigned to transcripts possibly coding for three BPV non-structural proteins. Amplification of BPV transcripts with primers specific to the mid-ORF suggests that the amino terminus of the capsid protein VP1 is not coded for by the mid-ORF as suggested by earlier studies, but instead results from one or both of the two small ORFs present upstream of the right ORF, in the same reading frame. / Ph. D.