Isolation and Characterization of Clinical RSV Isolates in Belgium during the Winters of 2016–2018

Van der Gucht, Winke; Stobbelaar, Kim; Govaerts, Matthias; Mangodt, Thomas; Barbezange, Cyril; Leemans, Annelies; De Winter, Benedicte; Van Gucht, Steven; Caljon, Guy; Maes, Louis; De Dooy, Jozef; Jorens, Philippe; Smet, Annemieke; Cos, Paul; Verhulst, Stijn; Delputte, Peter L.

We have isolated RSV from nasal samples from patients in the winter seasons of 2016-2017 and 2017-2018 and found that isolating infectious virus from nasal samples is most efficient from nasopharyngeal aspirates (50%) compared to nasopharyngeal swabs (27%). However, yield may also depend on timing of sampling compared to onset of symptoms and time between sampling and inoculation of cell culture. HEp-2 cells were used for isolation since they are permissive for most RSV strains and isolates described. One well-known exception is RSV B1, which infects HEp-2 cells, but viral titers remain low compared to other strains. However, infection of RSV B1 in Vero cells does yield a higher titer, which is also the case for the clinical isolate BE/ANT-B20/17 from this study. The clinical isolates were genotyped and characterized on their ability to grow and produce infectious virus in cell lines. Thermal stability was assessed at 37 • C (normal body temperature, incubation temperature), 32 • C (estimated nasal temperature) and 4 • C (storage temperature), fusion capacity and neutralization by palivizumab as specific features of the fusion protein and mucin mRNA expression of MUC1 and MUC4 as cell-tethered mucins, and MUC5AC and MUC5B as secreted mucins.