“Nanobodies”, similar to those of camels and llamas, have been tested in the lab against the viral strains that cause the worst sorts of intestinal infections. They are ten times smaller than normal antibodies.
In the fight against noroviruses, which cause acute gastroenteritis, the researchers at Baylor College of Medicine in Houston (USA) have successfully tested—in the laboratory, at least—tiny antibodies (nanobodies, to give them their technical name), developed from the antibodies of camelids (llamas, camels, alpacas), but modified using genetic engineering techniques to make them compatible with human cells. The results of the study have appeared in the scientific journal Nature Communications.
For years, researchers have been focusing their attention on camelid nanobodies, which are ten times smaller than human antibodies and which, thanks to their tiny size, can reach places where, in many cases, human antibodies cannot penetrate. Tests (often successful) have been conducted against different types of viruses, such as the ones that cause hepatitis B, influenza, polio and other diseases.
Positive results against the viruses that cause gastroenteritis
Now it is the turn of noroviruses, which, as we were saying above, are a family that consists of ten groups, five of which are human pathogens with characteristics similar to those of influenza and corona viruses—in other words, an exceptional capacity for mutation and adaptation, which makes them especially hard to fight.
Acute gastroenteritis infections caused by noroviruses are extremely common (approximately 684 million cases around the world annually) and they kill over 200,000 people each year, chiefly among the elderly and infants. At present, there are still no specific vaccines or drugs to combat these infections.
Testing on “organoids”
The researchers at Baylor College of Medicine specifically tested llama nanobodies on intestinal organoids infected with the type of norovirus that is most dangerous to humans, called GII.4 (organoids, as you may recall, are complex clusters of cells that mimic certain characteristics of “real” organs).
What was the outcome? Well, the nano-antibodies were able to block the noroviruses, pointing the researchers in the direction of a possible new type of therapy, which they even “photographed” using technologies such as crystallography and electron microscopy.
The viruses disintegrate
What is the mechanism of action of these nano-antibodies? To put it very simply, we could say that, when noroviruses duplicate, they go from a stable phase to a very unstable one, during which they “expose” several of their molecules. The nanobodies bind to one of these, preventing the virus from returning to its compact conformation. Remaining in an unstable state causes the death of the virus, within a short span of time, as it breaks apart.
All of this gives us cause to hope that a specific nanobody-based therapy may be on the way, one which could at least be used in the most severe and urgent of cases, and that we may also be able to research other therapies, based on the same mechanism of action but created in the lab and optimized.
