Three splicing patterns are used to excise the small intron common to all minute virus of mice RNAs

We identified three splicing patterns used to excise the small intron common to all three transcripts encoded by minute virus of mice. Sequence analysis of minute virus of mice-specific cDNAs indicated that two donor and two acceptor splice sites were used: in pattern 1, the most frequent, nucleotide 2280 was spliced to nucleotide 2377; in pattern 2, nucleotides 2317 and 2399 were joined. Oligonucleotide probes, each specific for one of the four possible splice junction sequences, were synthesized and hybridized to viral mRNAs immobilized on nitrocellulose filters. The probes specific for splice patterns 1 and 2 hybridized to all three viral mRNAs, as did a third oligomer specific for a splicing pattern in which nucleotides 2280 and 2399 were joined. The fourth potential splicing pattern, linking nucleotides 2317 and 2377, was not detected. The presence of three splicing patterns in the transcripts designated R2 and R3 would allow the translation of five distinct polypeptides from these two mRNAs.