Association of airborne virus infectivity and survivability with its carrier particle size

Although Laboratory generated virus aerosols have been widely studied in terms of infectivity and survivability, how they are related to particle size, especially in the submicron size range, is little understood. Four viruses (MS2 bacteriophage, transmissible gastroenteritis virus, swine influenza virus, and avian influenza virus) were aerosolized, size classified (100-450 nm) using a differential mobility analyzer (DMA), and collected onto gelatin filters. Uranine dye was also nebulized with the virus, serving as a particle tracer. Virus infectivity assay and quantitative reverse transcription-polymerase chain reaction were then used to quantify the amount of infectious virus and total virus present in the samples, respectively. The virus distribution was found to be better represented by the particle volume distribution rather than the particle number distribution. The capacity for a particle to carry virus increased with the particle size and the relationship could be described by a power law. Virus survivability was dependent on virus type and particle size. Survivability of the three animal viruses at large particle size (300-450 nm) was significantly higher than at particle size close to the size of the virion (100-200 nm), which could be due to the shielding effect. The data suggest that particle size plays an important role in infectivity and survivability of airborne viruses and may, therefore, have an impact on the airborne transmission of viral illness and disease. The data in this study do not support the use of MS2 bacteriophage as a general surrogate for animal and human viruses.