Nondefective rotavirus mutants with an NSP1 gene which has a deletion of 500 nucleotides, including a cysteine-rich zinc finger motif-encoding region (nucleotides 156 to 248), or which has a nonsense codon at nucleotides 153-155.

We isolated two nondefective bovine rotavirus mutants (A5-10 and A5-16 clones) which have nonsense mutations in the early portion of the open reading frame of the NSP1 gene. In the NSP1 gene (1,587 bases long) of A5-10, a nonsense codon is present at nucleotides 153 to 155 just upstream of the coding region (nucleotides 156 to 230) of a cysteine-rich Zn finger motif. A5-16 gene 5 (1,087 bases long) was found to have a large deletion of 500 bases corresponding to nucleotides 142 to 641 of a parent A5-10 NSP1 gene and to have a nonsense codon at nucleotides 183 to 185, which resulted from the deletion. Expression of gene 5-specific NSP1 could not be detected in MA-104 cells infected with the A5-10 or A5-16 clone or in an in vitro translation system using the plasmids with gene 5 cDNA from A5-10 or A5-16. Nevertheless, both A5-10 and A5-16 replicated well in cultured cells, although the plaque size of A5-16 was extremely small.