Tuesday, March 5, 2019

Dangerous bee virus might be innocent bystander

Beekeepers urged to rethink fears around deadly virus

Researchers at the University of Sydney have found that the relationship between the tissue-sucking Varroa mite and virulence of a virus of honey bees, has most likely been misunderstood.
The study challenges the long-held belief that the parasitic Varroa mite -- a mite that sucks the tissue of honey bees -- transmits the Deformed Wing Virus of honeybees and in doing so changes the virus to make it more virulent and deadly.
Research published today in Proceedings of The Royal Society B: Biological Sciences concludes that this belief is incorrect.
"The prevailing wisdom is that the mite selects for very virulent strains of the virus," said Professor Madeleine Beekman from the School of Life and Environmental Sciences at the University of Sydney.
"For that reason, the virus is now known as a very dangerous virus and the Australian beekeepers are adamant this virus should not get into the country. In fact, there is legislation that prevents the import of any bee products that could contain the virus. But our work shows that the virus is more likely to be an innocent bystander."
Australia is the only country in the world to remain free of the Varroa mite. This makes Australian honey and wax valuable because it is free of chemical residues used to eliminate the parasite.
"Australia is the last country on the planet to produce completely pure honey," says Professor Beekman. "But the mite is highly likely to arrive in Australia on shipping containers so we need to understand how the mite and the virus interact."
Professor Beekman and her team in the Behaviour and Genetics of Social Insects Lab injected honey bee pupae with high levels of Deformed Wing Virus which is carried by the mite to test if the virus was highly virulent due to changes in the transmission route that occurred via the Varroa mite.
The team found the transmission route used by the Varroa mite selects against viruses that are much more virulent than the Deformed Wing Virus, such as Sacbrood virus and Black queen cell virus. These viruses normally suppress Deformed Wing Virus. The elimination of Sacbrood and Black Queencell virus leaves just Deformed Wing Virus, which does not kill the bees.
"Our work therefore changes our understanding of the effect Varroa has on Deformed Wing Virus and the health of honey bee colonies
"It means we don't have to be scared of the virus. Instead we need to focus on eliminating the mite and reducing its numbers."
The results will also have an impact on the ways the Australian beekeepers can prepare themselves for the arrival of Varroa.
"But the importation of the sperm is currently forbidden because of the threat of Deformed Wing Virus, which can be present in bee sperm. Perhaps beekeepers can now convince the authorities that bee sperm is safe."
"If we want to protect the bees, it now no longer seems to make sense to try to combat the virus”.
 "Instead, there needs to be a renewed focus on ensuring the number of mites in honey bee colonies remain low."
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Source: University of Sydney

Thursday, February 14, 2019

Genome structure of malaria parasites linked to virulence

An international research has found that malaria parasite genomes are shaped by parasite-specific gene families, and that this genome organization strongly correlates with the parasite's virulence. The findings highlight the importance of spatial genome organization in gene regulation and the control of virulence in malaria parasites.
The findings highlight the importance of spatial genome organization in gene regulation and the control of virulence in malaria parasites.
 "Novel intervention strategies targeting the genome structure could thus mark a breakthrough for both vaccine and drug development against malaria."Study results appear in the Proceedings of the National Academy of Sciences.

Institute Leadership assistant professor of computational biology at La Jolla Institute for Immunology and an assistant adjunct professor at the UC San Diego School of Medicine, and colleagues investigated the 3-D genome organization in five malaria parasites and two related parasites to identify possible connections between genome architecture and pathogenicity. They found that in all five malaria parasites
The most virulent species of malaria parasites use an "antigenic variation" mechanism to alter their surface proteins and avoid the host immune response. The ability of the parasite to switch its antigenic profile correlates with the parasite's high virulence. 

The researchers found that the two most pathogenic human malaria parasites -- Plasmodium falciparum and Plasmodium knowlesi -- share unique features in the organization of gene families involved in antigenic variation. P. falciparum and P. knowlesi, they report, have evolved unique gene families -- var and SICvar, respectively -- that enable these parasites to undergo antigenic variation.
"The organization of other Plasmodium genomes is also driven by their virulence genes -- but it is not as strongly seen in them as we see in P. falciparum and P. knowlesi," 
Le Roch was supported in the research by grants from the National Institutes of Health and UC Riverside.

Source: University of California