Survival of airborne influenza virus: Effects of propagating host, relative humidity, and composition of spray fluids

Abstract

Influenza A virus, strain WSN_H, propagated in bovine, human and chick embryo cell cultures and aerosolized from the cell culture medium, was maximally stable at low relative humidity (RH), minimally stable at mid-range RH, and moderately stable at high RH. Most lots of WSN_H virus propagated in embryonated eggs and aerosolized from the allantoic fluid were also least stable at mid-range RH, but two preparations after multiple serial passage in eggs showed equal stability at mid-range and higher RH's. Airborne stability varied from preparation to preparation of virus propagated both in cell culture and embryonated eggs. There was no apparent correlation between airborne stability and protein content of spray fluid above 0.1 mg/ml, but one preparation of lesser protein concentration was extremely unstable at 50 to 80 per cent RH. Polyhydroxy compounds exerted a protective effect on airborne stability.