Analysis of the Thermal Stability of a Diverse Panel of Recombinant Respiratory Syncytial Virus (RSV) Strains

Indianapolis, IN

Respiratory syncytial virus (RSV) is a respiratory pathogen of infants and the elderly and is associated with upper and lower respiratory disease. Vaccine development for RSV has been hindered by poor immunogenicity in target populations, genetic and physical instabilities, and vaccine-enhanced disease. The fusion and attachment proteins of RSV, F and G, have historically been responsible for inducing neutralizing antibodies. However, little remains known about how differences in RSV F and G affect virus replication and stability. In this study, we examine the replication and thermal stability of a panel of recombinant RSV strains which express the F and G proteins of laboratory and clinical isolates. Differences in replication were observed between strains during infections in HEp2 and Vero cell lines, however there were no major differences in replication for each virus in different cell lines. To evaluate thermal stability, the RSV panel was incubated at 4C, 32C, and 37C before determining reductions in infectious titer. The thermal stability of all viruses when tested at 32C, and 37C was reduced relative to 4C. We also evaluated stability following multiple cycles of freezing and thawing. Freeze-thaw cycling resulted in reductions to infectious yield for all viruses and relative stability to freezing and thawing correlated directly with thermal stability. There was no correlation between virus replication and thermal stability. These findings provide insight into the role of RSV strain-specific differences in surface proteins and may provide guidance of selection of RSV strains or specific F or G antigens in future vaccine design.