Norovirus, Stomach virus can be spread through saliva
The transmission of these so-called enteric viruses through saliva suggests that coughing, talking, sneezing, sharing food and utensils, and even kissing are all capable of spreading the virus. The new findings still need to be confirmed in human studies.
The findings, appearing in the journal Nature, which could lead to better ways to prevent, diagnose, and treat diseases caused by these viruses, potentially saving lives. The study was led by the National Heart, Lung, and Blood Institute (NHLBI), a division of the NIH.
Researchers already know that Enteric viruses, such as norovirus and rotavirus, can be spread by eating food or drinking liquid contaminated with stool that contains these viruses.. Intestinal viruses are thought to travel through the salivary glands and target the intestines, exiting later in the stool. Although some scientists have suspected there may be another route of transmission, this theory has remained largely untested to date.
Transmission of enteric viruses through saliva
Now researchers will need to confirm that it is possible to transmit the intestinal virus through saliva in humans. If that were discovered, the researchers say, they might also find that this route of transmission is even more common than the normal route. Such a finding could help explain why the high number of enteric virus infections each year worldwide does not fully account for fecal contamination as the only route of transmission, they say.
“This is completely new territory because these viruses are thought to grow only in the environment,” said senior author Nihal Altan-Bonnet, PhD, head of the Host-Pathogen Dynamics Laboratory at NHLBI. intestine. “The salivary transmission of enteric viruses is another class of transmission that we don’t know yet. It’s a whole new way of thinking about how these viruses can be transmitted, how they can be transmitted. can be diagnosed and, most importantly, how their spread can be minimized.”
Altan-Bonnet, who has been studying enteric viruses for many years, said the discovery was purely coincidental. Her team conducted experiments with enteric viruses in newborn mice, which is the animal model of choice for studying these infections because their immature digestive and immune systems make it difficult for humans to develop. they are susceptible to infection.
For the current study, the researchers fed a group of newborn mice less than 10 days old with norovirus or rotavirus. The pups were then returned to the cage and allowed to suckle from their mothers, which were initially virus-free. After just one day, one of Altan-Bonnet’s team members, NHLBI researcher and study co-author Sourish Ghosh, PhD, noticed something unusual. The pups showed a spike in IgA antibodies – a key disease-fighting component – in their intestines. This is surprising given that the pups’ immune systems are immature and should not be expected to produce their own antibodies at this stage.
Ghosh also noticed other abnormalities: The viruses were multiplying in the mothers’ breast tissue (milk duct cells) at high levels. When Ghosh collected milk from the breasts of rat mothers, he found that the duration and degree of IgA rise in the mothers’ milk reflected the duration and extent of IgA rise in the gut of the pups. It appears that the mothers’ breast infection spurred the production of virus-fighting IgA antibodies in their breast milk, the researchers said, which ultimately helped clear the infection in the mothers. their pups, the researchers said.
Eager to know how the virus entered the mothers’ breast tissue in the first place, the researchers conducted additional experiments and found that the pups did not transmit the virus to their mothers. through the usual route – by leaving contaminated feces in a common life. space for their mother to eat. That’s when the researchers decided to see if the virus in the mothers’ breast tissue could have come from the saliva of infected pups and somehow spread during lactation.
To test the theory, Ghosh collected saliva and salivary gland samples from pups and found that the salivary glands were replicating these viruses to a very high degree and shedding the virus into the saliva with bulk. Additional experiments quickly confirmed the salivary theory: Sucking caused both mother-to-child and mother-to-child transmission of the virus.