Dr. Obdulio García-Nicolás and Prof. Charaf Benarafa
Institute of Virology and Immunology
A recent study principally funded by the MCID has been published in PLOS Pathogens and highlights the importance of studying neglected diseases.
Climate change is driving a rise in mosquito-borne diseases like Zika, Japanese encephalitis virus and West Nile virus. As well as being spread by mosquitoes, these diseases can also spread through direct contact with infected animals or samples. To improve pandemic preparedness programmes, we should also consider neglected insect-borne viruses like Wesselbron virus (WSLV). It is transmitted by Aedes spp. mosquitoes and primarily affects sheep and goats, causing abortions and mortality rates of up to 30% in newborns. Although rare, several human infections have been documented, particularly in laboratory personnel in contact with infected animals or contaminated samples, suggesting potential transmission without the involvement of a mosquito vector.
One problem with studying neglected viruses like WSLV is limited access to contemporary or relevant viral strains. WSLV has two clades, but only clade II viruses are readily available. To address this, and with support from the BioPreparedness BioBank Core Activity of the MCID, a reverse genetics virus stock was generated by TAR cloning which was identical to the published sequence. This virus was then used along with a clade II virus to infect two groups of lactating ewes. All animals became sick and virus was found in various body fluids in the infected sheep. Notably, two ewes from each group transmitted the virus to their lambs, likely through their milk, which had high levels of the virus. Interestingly, biochemical markers of liver damage were also more pronounced with the clade I virus, whereas brain lesions were only observed in animals infected with the clade II virus, suggesting a distinct tissue tropism for WSLV strains.
In conclusion, this study underscores the urgent need to include neglected mosquito-borne viruses like Wesselsbron virus (WSLV) in pandemic preparedness strategies, especially as climate change accelerates the spread of such pathogens. By generating a reverse genetics virus of the less accessible clade I strain, the research team were able to demonstrate key differences in disease severity and tissue targeting between WSLV clades. The detection of the virus in multiple body fluids and its likely transmission through milk from ewe to lamb further highlights the complex transmission dynamics and potential zoonotic risk. These findings reinforce the importance of improved surveillance, access to diverse viral strains, and continued investment in research to better understand and mitigate emerging viral threats.
Zimoch, Marta, et al. "Mosquito-independent milk-associated transmission of zoonotic Wesselsbron virus in sheep." PLoS pathogens 20.12 (2024): e1012751.
