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.

Differences in the F protein are shown to be involved in thermal stability of viral particles [37] . Aliquots of each virus containing 1×10 5 PFU/mL were incubated at three different temperatures: 37 • C (in vitro incubator temperature and core body temperature) ( Figure 5A,B) , 32 • C (upper airway temperature) (Figure 5C ,D) and 4 • C (storage temperature) ( Figure 5E ,F) for 24 h, 48 h and 72 h. Aliquots were snap frozen in liquid nitrogen and used for conventional plaque assay to quantify the remaining infectious virus. For all RSV-A isolates and RSV A2, higher temperatures were associated with a faster decay of infectious virus. Curiously, BE/ANT-A11/17 maintained higher PFU at 4 • C than other RSV-A isolates although at the other temperatures, there was no difference. Additionally, BE/ANT-A18/17 was preserved slightly better at 4 • C, however at 72 h no viable virus was detected. RSV-B isolate BE/ANT-B20/17 retained higher titers for the duration of the experiment compared to other RSV-B isolates but its overall stability was less than the reference RSV B1. The only exception is at 32 • C, where its viral titers remained higher than RSV B1. Isolate BE/ANT-B15/17 seems to decay especially fast at any other temperature than 37 • C.