This class of viruses develops in the salivary glands of rats and can cause diarrheal diseases, especially those that suffer from vessels and cruises.
Scientists have discovered that the spread of norovirus, the virus responsible for causing severe diarrheal disease, which is famous for widespread outbreaks on cruise ships, may be transmitted through the saliva of rats.
search can tie down Reversible source of a common virus, which afflicts billions of people worldwide every year and can be fatal. The discovery could lead to better ways to prevent, diagnose and treat diseases caused by these viruses, which could potentially save lives.
The findings were published in the journal Nature, The study was led by the National Heart, Lung and Blood Institute (NHLBI), part of the NIH.
broadcast of so called enteric virus Saliva is known to spread the virus through coughing, talking, sneezing, sharing food and utensils, and even kissing.
Researchers have known for some time that enteric viruses, such as norovirus and rotavirus, can be spread by eating food or drinking fluids contaminated with fecal matter containing these viruses.
Enteric virus was thought to bypass salivary gland and target the intestines, later excreted through the stool. Although some scientists have suspected that there may be another route of transmission, this theory has remained largely unproven until now.
Now researchers will need to confirm that salivary transmission of intestinal virus to humans is possible. If they find that it is, the researchers said, they may also find that this route of transmission is even more common than the traditional route.
Such a finding could help explain, he said, why the high number of enteric virus infections worldwide each year is not sufficiently attributable to fecal contamination as the sole transmission route.
“This is completely new territory because these viruses were thought to grow only in the intestines,” said senior author Nihal Altan-Bonet, PhD, head of the Laboratory of Host-Pathogen Dynamics at the NHLBI. “Saliva transmission of enteric viruses is another layer of transmission we didn’t know about. There’s a whole new way of thinking about how these viruses might be transmitted, how they can be diagnosed, and most importantly, how how their spread can be reduced.”
Alton-Bonnet, who has studied intestinal viruses for years, said the discovery was absolutely grim. His team was experimenting with enteric viruses in infant mice, which are the animal model of choice for studying these infections because their immature digestive and immune systems make them susceptible to infection.
For the current study, researchers fed a group of newborn mice that were less than 10 days old with norovirus or rotavirus. The mouse pups were then returned to the cages and allowed to suckle their mothers, who were initially virus free. After just one day, one of the members of Altan-Bonnet’s team, NHLBI researcher and study co-author Saurish Ghosh, Ph.D, noticed something unusual. The mouse pups showed an increase in IgA antibodies – important disease-fighting components – in their guts. This was surprising given that the immune systems of mouse pups were immature and were not expected to make their own antibodies at this stage.
Ghosh also noticed other unusual things: The virus was replicating in the mothers’ breast tissue (milk duct cells) at high levels. When Ghosh collected milk from the breasts of mouse mothers, he found that the timing and level of IgA rise in the mothers’ milk reflected the timing and level of IgA rise in the guts of their pups. Researchers said it seemed that infection in the mothers’ breasts promoted the production of virus-fighting IgA antibodies in their breast milk, which ultimately helped clear the infection in their puppies.
Curious to learn how the virus got into the mothers’ breast tissue in the first place, the researchers conducted additional experiments and found that the rat pups did not transmit the virus to their mothers via the traditional route – by sharing contaminated feces. Leaving a place to live for their mothers to swallow. That’s when the researchers decided to see if the viruses in the mothers’ breast tissue came from the saliva of infected pups and were somehow spread during breastfeeding.
To test the theory, Ghosh collected saliva samples and salivary glands from rat pups and found that the salivary glands were replicating these viruses at very high levels and secreting large amounts of virus into the saliva. Additional experiments quickly confirmed the saliva theory: mother-to-puppy and puppy-to-mother viral transmission was caused by sucking.