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The Epstein-Barr virus (EBV) is very widespread. More than 90 percent of the world's population is infected, with varying consequences. Although the infection does not usually affect people, in some, it can cause glandular fever or various types of cancer. Researchers at the German Cancer Research Center (DKFZ) have now discovered why different virus strains cause very divergent courses of disease.
More than 90 percent of all people become infected with the Epstein-Barr virus (EBV) during their lifetime. The infection usually remains undetected. However, the virus can also cause diseases—with regional differences: Glandular fever (infectious mononucleosis) primarily occurs in Europe and North America, and normally affects adolescents or young adults. In equatorial Africa, Burkitt lymphoma is associated with EBV infection. And in Taiwan, southern China and Southeast Asia, the virus often causes nasopharyngeal carcinomas, cancers of the nose and throat area. This is one of the most common types of cancer in young adults in these countries.
"Nasopharyngeal carcinomas are sometimes seen here too, but really very rarely," commented Henri-Jacques Delecluse from DKFZ. So how does EBV cause completely different diseases in different parts of the world? "One possible explanation is that different types of virus are responsible," Delecluse explained. "And we have now found evidence of precisely that." The DKFZ researchers are publishing their results in the journal Nature Microbiology.
In the laboratory, Delecluse and his team studied a virus strain that had previously been isolated from a nasopharyngeal carcinoma. M81, as this particular type of virus is called, has certain peculiarities. The researchers had previously discovered that M81 infects not only the immune system's B cells, but also epithelial cells of the nasal mucous membrane very efficiently. In contrast, virus strains that cause glandular fever in Europe almost only infect B cells. And although the virus strains that are common there cause the infected B cells to multiply in a Petri dish, they do not produce any new virus particles, unlike M81. To find out how this variant affects the behavior of the virus, the DKFZ researchers used molecular biology tools to extract EBER2 from the M81 genome. "The virus was, indeed, no longer able to multiply in the infected cells," Delecluse noted. Even when an EBER2 element from a virus strain that is widespread in Europe was inserted into the M81 virus, it was no longer able to produce virus particles.
"We have therefore finally found evidence that different types of virus can be responsible for different diseases," said Delecluse, emphasizing the significance of his results. "This finding is a strong argument for pressing on with vaccine research in order to develop protection against the most dangerous strains of EBV in future," he concluded. The vaccination against human papillomavirus (HPV), which can cause cervical cancer, already uses a similar principle.
Findings published in September 9, 2019 in Nature Microbiology:
La mononucléose est très répandu dans le monde et touche beaucoup de personnes. Selon les souches virales, la mononucléose peut être bénigne (elle provoque une fièvre) ou elle peut donner des cancers (carcinome du nasopharynx).
Des chercheurs allemands étudient les différentes souches, ils découvrent que : le patient qui a une mononucléose peut développer un cancer s’il a une souche M81 qui attaquent les cellules B et les cellules épithéliales de la muqueuse nasale.
Cela dépend des gènes, notamment EBER2 qui aide M81 à se multiplier.
Cela est prometteur afin de trouver des vaccins selon les souches de l’EBV.