Thomas J Mariani | PubMed Health

PubMed2025

A Respiratory Syncytial Virus trailer sequence modulates viral replication and copy-back defective viral genome generation and propagation kinetics.

Copy-back defective viral genomes (cbDVGs) are key inducers of antiviral responses during negative-sense RNA virus infection. Once considered byproducts of in vitro viral replication, cbDVGs have since been detected in clinical specimens and implicated in affecting infection outcomes. The molecular mechanism of cbDVG generation remains unclear, thereby hindering our ability to manipulate cbDVG production during infection for therapeutic gain. Previous work showed that respiratory syncytial virus (RSV) cbDVG re-initiation sites cluster in trailer-end hotspots R1, R2, and R3, and that a poly-U mutation in R1 selectively reduced cbDVG formation at the mutated region. Here, we reported that a 10U mutation in R2 drastically reduced cbDVGs in this region in both minigenome and recombinant virus systems. Furthermore, during high-MOI passaging of the R2-10U virus, we observed delayed detection of cbDVGs with re-initiation sites in R1-R3 (trailer cbDVGs) compared to WT, while no differences in virus titers were observed. Interestingly, we observed the rapid emergence and accumulation of a viral variant bearing a 2-ribonucleotide deletion (R2-8U) within the R2-10U mutation sequence as early as P0. Compared to R2-10U, the R2-8U virus was stable, displayed faster generation and accumulation of trailer cbDVGs, restored cbDVGs with R2 re-initiation sites, and exhibited enhanced genomic replication. Overall, our data identify a sequence in the RSV trailer whose mutation critically modulates both viral replication and the generation/propagation of trailer cbDVGs. Our data also suggest that cbDVG generation, particularly near the trailer, may be an evolutionary tradeoff for more rapid virus genomic replication.

defective viral genome generation and accumulation↗

PubMed2024

Association of disease severity and genetic variation during primary Respiratory Syncytial Virus infections.

BACKGROUND: Respiratory Syncytial Virus (RSV) disease in young children ranges from mild cold symptoms to severe symptoms that require hospitalization and sometimes result in death. Studies have shown a statistical association between RSV subtype or phylogenic lineage and RSV disease severity, although these results have been inconsistent. Associations between variation within RSV gene coding regions or residues and RSV disease severity has been largely unexplored. METHODS: Nasal swabs from children (< 8 months-old) infected with RSV in Rochester, NY between 1977-1998 clinically presenting with either mild or severe disease during their first cold-season were used. Whole-genome RSV sequences were obtained using overlapping PCR and next-generation sequencing. Both whole-genome phylogenetic and non-phylogenetic statistical approaches were performed to associate RSV genotype with disease severity. RESULTS: The RSVB subtype was statistically associated with disease severity. A significant association between phylogenetic clustering of mild/severe traits and disease severity was also found. GA1 clade sequences were associated with severe disease while GB1 was significantly associated with mild disease. Both G and M2-2 gene variation was significantly associated with disease severity. We identified 16 residues in the G gene and 3 in the M2-2 RSV gene associated with disease severity. CONCLUSION: These results suggest that phylogenetic lineage and the genetic variability in G or M2-2 genes of RSV may contribute to disease severity in young children undergoing their first infection.

Humans↗