By Yogesh Sharma
Published on 13, August, 2018
Japanese Encephalitis, a leading form of viral encephalitis is a major problem in India. It is caused by mosquito-borne JE virus which belongs to the same genus as dengue and yellow fever.
In a new study, a team of researchers led by scientists of the National Brain Research Centre (NBRC) has identified proteins that facilitate entry of JE virus inside the brain cells. Two brain cell proteins - PLVAP (Plasmalemma vesicle-associated protein) and GKN3 (Gastrokine3) - facilitate the entry of the virus into brain cell. The study has been done in laboratory mice.
JE infection occurs when viral attachment proteins interact with cellular membrane proteins of host cells. In their study, scientists synthesized JEV E-glycoprotein (viral attachment protein) in bacteria followed by its collection and purification. The purified E protein was made to interact with cell membrane fraction of mouse brain to find out interacting partners from cell membrane. Following the binding of E protein with cellular partners, the interacting proteins were identified using two-dimensional gel electrophoresis and mass spectrometry.
“Amongst the identified proteins, PLVAP and GKN3 were shown to be present on neuronal cell surface which means they have a role in viral entry into neurons. We reconfirmed their presence on the surface of neurons isolated from mouse cerebral cortex, which validates their identity as neuronal proteins. In addition, PLVAP protein was found to be upregulated in human autopsy tissue of JE infection,” explained Dr Anirban Basu, senior scientist at NBRC who led the study.
Researchers also found that reducing PLVAP receptor in neurons decreased JEV entry and upregulating (increasing) them increased viral entry on the other hand. It shows the two proteins are important for viral invasion. “Identification of host proteins, important for viral entry into neurons provides us with candidates, whose targeting may be useful to block viral infection thus reducing disease severity,” added Dr Basu.
Now the team is planning to collaborate with some pharmaceutical companies to identify potential drug which may be able to block this receptor proteins. According to Dr. Basu, these receptors may be common for other viruses which target cells of the nervous system, like Zika, West Nile and even dengue. However, extensive research is needed for the confirmation.
“This research is highly significant and will advance the field towards development of therapies against JE”, commented Dr. Manjula Kalia, a scientist from Faridabad-based Translational Health Science And Technology Institute, who is not associated with this study.
Dr. Milind Gore, a former scientist from National Institute of Virology, Pune, said “this is one step further in understanding how 10-day old mice are sensitive for JE multiplication and hopefully some good work will come out in future”.