A putative wild-type or wild-type-like hairpin structure is required within 3′ untranslated region of Senecavirus A for virus replication

Abstract

The 3′ untranslated region (UTR) of Senecavirus A (SVA) was predicted to harbor two hairpin structures, hairpin-I and -II. The former is composed of two internal loops, one terminal loop and three stem regions; the latter comprises one internal loop, one terminal loop and two stem regions. In this study, we constructed a total of nine SVA cDNA clones, which contained different point mutations within a stem-formed motif in the hairpin-I or -II, for rescuing replication-competent viruses. Only three mutants were successfully rescued and moreover genetically stable during at least five serial passages. Computer-aided prediction showed these three mutants bearing either a wild-type or a wild-type-like hairpin-I in their individual 3′ UTRs. Neither wild-type nor wild-type-like hairpin-I could be computationally predicted to exist in 3′ UTRs of the other six unviable “viruses”. The results suggested that the wild-type or wild-type-like hairpin-I was necessary in the 3′ UTR for SVA replication.