Chimeric bovine respiratory syncytial virus with attachment and fusion glycoproteins replaced by bovine parainfluenza virus type 3 hemagglutinin-neuraminidase and fusion proteins

Chimeric bovine respiratory syncytial viruses (BRSV) expressing glycoprotei ns of bovine parainfluenza virus type 3 (BPIV-3) instead of BRSV glycoprote ins were generated from cDNA. In the BRSV antigenome cDNA, the open reading frames of the major BRSV glycoproteins, attachment protein G and fusion pr otein F, were replaced individually or together by those of the BPIV-3 hema gglutinin-neuraminidase (HN) and/or fusion (F) glycoproteins. Recombinant v irus could not be recovered from cDNA when the BRSV F open reading frame wa s replaced by the BPIV-3 F open reading frame. However, cDNA recovery of th e chimeric virus rBRSV-HNF, with both glycoproteins replaced simultaneously , and of the chimeric virus rBRSV-HN, with the BRSV G protein replaced by B PIV-3 HN, was successful. The replication rates of both chimeras were simil ar to that of standard rBRSV. Moreover, rBRSV-HNF was neutralized by antibo dies specific for BPIV-3, but not by antibodies specific to BRSV, demonstra ting that the BRSV glycoproteins can be functionally replaced by BPIV-3 gly coproteins. In contrast, rBRSV-HN was neutralized by BRSV-specific antisera , but not by BPIV-3 specific sera, showing that infection of rBRSV-HN is me diated by BRSV F. Hemadsorption of cells infected with rBRSV-HNF and rBRSV- HN proved that BPIV-3 HN protein expressed by rBRSV is functional. Colocali zation of the BPIV-3 glycoproteins with BRSV M protein was demonstrated by confocal laser scan microscopy. Moreover, protein analysis revealed that th e BPIV-3 glycoproteins were present in chimeric virions. Taken together, th ese data indicate that the heterologous glycoproteins were not only express ed but were incorporated into the envelope of recombinant BRSV. Thus, the e nvelope glycoproteins derived from a member of the Respirovirus genus can t ogether functionally replace their homologs in a Pneumovirus background.