2023-12-27 11:43:34
The cultivation method apparently also allows longer-term studies on noroviruses.
Scientists from Singapore are solving an old problem in virus research in the laboratory. According to their own statements, they have developed a method for the first time to easily cultivate noroviruses using zebrafish embryos. This is the prerequisite for researching the classic pathogens of acute gastrointestinal infections, which often occur on a large scale.
“Human norovirus (HuNoV) is currently the leading cause of acute gastroenteritis illnesses worldwide, causing an estimated 684 million episodes of diarrhea annually, resulting in around 212,000 deaths. For a long time, the lack of a system for culturing the pathogen in the laboratory hampered research of viruses,” wrote Li Dan and his co-authors from the University of Singapore in the journal of the American Society for Microbiology (Applied and Environmental Microbiology; doi: 10.1128/aem.00115-23).
Although a new cultivation method has recently been developed, it relies on the use of samples from intestinal biopsies. According to virologists, material for this is often difficult to find; the ongoing reproduction of pathogens using the process is complicated. The cultivation of pathogens in the laboratory, including viruses, is the prerequisite for studying their characteristics as well as for the development of diagnostic procedures and the search for therapeutic agents.
In the search for a better and easier-to-use process, Li Dan’s team turned to a model organism that has been established in biology research for around three decades: zebrafish. For example, the embryonic development of vertebrates has been researched on them for a long time. Around 70 percent of zebrafish genes are also found in humans. The attitude is simple. A pair of zebrafish can produce around 300 eggs per week. This initially creates embryos. Larvae finally hatch two days after fertilization. They are transparent, which allows their development to be easily observed on a single-cell basis.
The scientists infected both larvae and embryos of zebrafish with three different genotypes of norovirus. Already on the first day after infection, the virus yield in the embryos exceeded that after infection of larvae. Norovirus reproduction lasted six days in the embryos.
The cultivation method apparently also allows longer-term studies on noroviruses: the scientists were able to transmit the resulting viruses to new zebrafish embryos up to four times in a row. When added to saliva, the noroviruses showed properties that are necessary for infection in humans. When irradiated with UV light, a dependence on the effect of radiation was clearly demonstrated in the laboratory.
Li Dan: “The zebrafish embryo model represents an essential improvement in the methods for culturing noroviruses. It is highly efficient and robust. This will broaden and deepen research on noroviruses.” In addition to epidemiological studies, this also makes it possible to establish disinfection parameters, for example. “Such inactivation parameters are urgently needed for the management of drinking water and for the food industry to prevent the spread of viruses.”
Noroviruses are extremely infectious because they can be transmitted through direct contact as well as through contaminated food, water and air. They cause acute illnesses with vomiting and diarrhea. Kindergartens or schools are also often affected by large numbers of cases of illness occurring within hours.
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