Chimeric Bovine Respiratory Syncytial Virus with Glycoprotein Gene Substitutions from Human Respiratory Syncytial Virus (HRSV): Effects on Host Range and Evaluation as a Live-Attenuated HRSV Vaccine

Abstract

We recently developed a system for the generation of infectious bovine respiratory syncytial virus (BRSV) from cDNA. Here, we report the recovery of fully viable chimeric recombinant BRSVs (rBRSVs) that carry human respiratory syncytial virus (HRSV) glycoproteins in place of their BRSV counterparts, thus combining the replication machinery of BRSV with the major antigenic determinants of HRSV. A cDNA encoding the BRSV antigenome was modified so that the complete G and F genes, including the gene start and gene end signals, were replaced by their HRSV A2 counterparts. Alternatively, the BRSV F gene alone was replaced by that of HRSV Long. Each antigenomic cDNA directed the successful recovery of recombinant virus, yielding rBRSV/A2 and rBRSV/LongF, respectively. The HRSV G and F proteins or the HRSV F in combination with BRSV G were expressed efficiently in cells infected with the appropriate chimeric virus and were efficiently incorporated into recombinant virions. Whereas BRSV and HRSV grew more efficiently in bovine and human cells, respectively, the chimeric rBRSV/A2 exhibited intermediate growth characteristics in a human cell line and grew better than either parent in a bovine line. The cytopathology induced by the chimera more closely resembled that of BRSV. BRSV was confirmed to be highly restricted for replication in the respiratory tract of chimpanzees, a host that is highly permissive for HRSV. Interestingly, the rBRSV/A2 chimeric virus was somewhat more competent than BRSV for replication in chimpanzees but remained highly restricted compared to HRSV. This showed that the substitution of the G and F glycoproteins alone was not sufficient to induce efficient replication in chimpanzees. Thus, the F and G proteins contribute to the host range restriction of BRSV but are not the major determinants of this phenotype. Although rBRSV/A2 expresses the major neutralization and protective antigens of HRSV, chimpanzees infected with this chimeric virus were not significantly protected against subsequent challenge with wild-type HRSV. This suggests that the growth restriction of rBRSV/A2 was too great to provide adequate antigen expression and that the capacity of this chimeric vaccine candidate for replication in primates will need to be increased by the importation of additional HRSV genes. Bovine respiratory syncytial virus (BRSV) andHuman respiratory syncytial virus (HRSV) are closely related members of the Pneumovirus genus within the subfamily Pneumovirinae, family Paramyxoviridae, order Mononegavirales (6, 36). BRSV is a major cause of respiratory tract disease in cattle (32, 44). HRSV is the most important causative agent of viral pediatric respiratory disease worldwide (6). A licensed vaccine against HRSV is not available, though several promising candidates for attenuated live vaccines recently have been developed (references 17, 46, 47, and 48, and references therein).The genomes of HRSV and of BRSV are single-stranded, negative-sense RNAs of 15,222 nucleotides (nt) (HRSV A2) and 15,140 nt (BRSV ATue51...

Recombinant Newcastle disease virus as a viral vector: effect of genomic location of foreign gene on gene expression and virus replication

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Respiratory syncytial virus (RSV) fusion protein expressed by recombinant Sendai virus elicits B-cell and T-cell responses in cotton rats and confers protection against RSV subtypes A and B

“…RSV and PIV vaccine candidates include cold-adapted or hostrange-restricted viruses in unmodified or recombinant form [15][16][17][18]. Various subunit, fusion protein or peptide vaccines have also been tested in the RSV field.…”

New Generation Live Vaccines against Human Respiratory Syncytial Virus Designed by Reverse Genetics

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