Whereas it was always assumed that viruses were most effective at spreading illness by attacking human cells as individual virus particles, new research demonstrates that viral particles concealed in a membrane can mount a much more potent attack on individual human cells.
Experiments using mice and piglets show the severity of illness is much greater when the animals are exposed to vesicle-enclosed virus clusters. Stools of infected hosts contain norovirus and rotavirus within vesicles of exosomal or plasma membrane origin. These vesicles remain intact during fecal-oral transmission and thereby transport multiple viral particles collectively to the next host, enhancing disease severity. Vesicle-cloaked viruses are non-negligible populations in stool and have a disproportionately larger contribution to infectivity than free viruses. The study highlights a need for antivirals targeting vesicles and virus clustering.
Vesicle-Cloaked Virus Clusters Are Optimal Units for Inter-organismal Viral Transmission Santiana, Marianita et al. Cell Host & Microbe , Volume 24 , Issue 2 , 208 – 220.e8