Gastrointestinal viruses cause stomach pain, vomiting, and diarrhea, and are generally thought to be transmitted fecal-oral: Viruses in one host’s feces enter another host (for example, through contaminated food), replicate in their guts, and It is excreted in the feces and replicated in this form. While previous studies have detected enterovirus genomic RNA in the saliva of gastrointestinal virus-infected individuals, these detections have long been thought to be caused by gut contaminants.
However, Nihal Altan-Bonnet and colleagues showed evidence that enteroviruses can infect the salivary glands of mice, and that saliva can transmit the virus.
On June 29, 2022, researchers from the National Institutes of Health (NIH) published a research paper titled: Enteric viruses replicate in salivary glands and infect through saliva in Nature.
The study found that gastrointestinal viruses such as norovirus and rotavirus may be transmitted through saliva. The findings reveal a previously unknown route of transmission for the virus, or suggest that efforts to curb the spread of the virus require better health technology.
The team found that a few days after the pups were vaccinated with murine norovirus or rotavirus, the mothers of the mice also showed signs of infection. The researchers found genomic RNA from murine norovirus or rotavirus in the mammary glands of mouse mothers, indicating that mammary glands may be the site of replication of enteroviruses, suggesting that sucking milk from mouse pups may be a transmission route.
In adult mice, some (but not all) strains of murine norovirus or rotavirus have been found to replicate in the salivary glands, and injection of saliva from infected adult mice also resulted in infection in pups .
The discovery that enteroviruses can replicate in the salivary glands may have implications for the study of viral infections and their potential therapies. The authors demonstrate that mini salivary glands—organoids derived from mouse or human salivary gland cells—may be used to culture murine and human noroviruses, respectively. The mini salivary gland system may be a cheaper and simpler alternative to the current “mini-gut” (gut organoid) system used to replicate research noroviruses.