In 2015, researchers showed that polioviruses could travel in groups—or “packets”—that is, membrane-bound vesicles containing multiple virus particles. The researchers used the Trojan horse analogy to describe it. But they could not say whether the system applied to animals and humans, or how effective the “horses” were in infecting host cells.
To find out, the researchers focused on rotaviruses and noroviruses, which are mainly spread through stool-contaminated food or liquids. And they found that the viruses were indeed shed as packet-enclosed clusters in the stool. Moreover, the virus clusters were significantly more infectious than the free, unbound viruses in the fecal samples tested.
The researchers say the high level of infectiousness is likely due to the vesicles delivering many viruses at once to the target tissue. The vesicles also protect their “viral cargo” from being destroyed by prolonged exposure to enzymes and may even make it invisible to the antibodies in the stool or gut.
The virus packets are not only extremely potent, but aggressive. More studies are needed, and more antivirals, the researchers say, but in the meantime, soap and water can help keep them down.