Infectious bursal disease virus rescued efficiently with 3′ authentic RNA sequence induces humoral immunity without bursal atrophy

Abstract

A reverse genetics infectious bursal disease virus (RG-IBDV) that contained authentic 3′ RNA sequence was characterized both in vitro and in vivo. LP1-IBDV, a cell line-adapted IBDV strain variant E (VE) was used as the parent virus for constructing viral cDNA clones. Authentic 3′ RNA sequence was generated by using cis-acting hepatitis delta virus ribozyme (HDR). The absence of HDR in the clones did not affect viral protein expression, but the obtained viral titers were reduced by 200-folds when compared to the clones with HDR sequence. RG-IBDV generated from clones with HDR sequence was similar to LP1-IBDV by plaque size, growth kinetics and electron microscopic morphology. RG-IBDV did not cause bursal atrophy in 3-week-old chickens at 3, 7 and 17 days post infection (DPI) and induced high ELISA and neutralizing antibody titers to IBDV at 7 and 17 DPI. The results indicated that RG-IBDV can be generated efficiently with an authentic 3′ RNA terminus and the obtained RG-IBDV is non-pathogenic and immunogenic with the potential as a vaccine strain that can be further genetically modified to broaden its application.