Thermal Stabilization of Virus Based on Surface Properties
Chemical Engineering Grain Processing Seminar Series
Department of Chemical Engineering
Michigan Technological University
Advisor: Dr. Caryn Heldt
Abstract: Viral diseases continue to take the lives of millions of people each year. The most effective method to prevent viral infection is with vaccines. In order for viral vaccines to be effective they must be transported and stored at cold temperatures. If temperatures are not maintained, the vaccine may lose its potency and could no longer be effective in fighting disease. This is called the cold storage problem. Finding a way to thermally stabilize a virus so a vaccine does not need to be transported and stored in cold temperatures is important to the health and safety of many people. We are exploring the use of polyelectrolyte dense phases to stabilize viruses. But to reduce the need to randomly screen different polyelectrolytes, we have chosen to first explore viral surface properties.
The property we have focused on is virus surface charge. The surface charge of virus particles is pH dependent, which dictates the mobility and controls the colloidal behavior in virus sorption processes. A single particle method of chemical force microscopy (CFM) allows the quantitation of the virus surface charges. CFM can measure the surface charge of complicated virus particles by using an atomic force microscopy (AFM) probe terminated with ionizable groups. The change of adhesion forces measured as a function of pH is due to a change of virus surface electrostatic properties. The liquid environment used during CFM helps to maintain a more natural form of the virus without deformation, disassembly, or dehydration.
We have developed a method of encapsulation of virus particles in polymers that relies on the electrostatic interaction of virus with polypeptides. Encapsulating virus particles in polymers is a possible solution to the cold storage problem. When oppositely charged polypeptides are in solution, the electrostatic interactions of the polypeptides create a dense phase liquid called a complex coacervate. At a charge ratio close to 0.5 (50% positively charged polypeptides and 50% negatively charged polypeptides), all of the virus particles are extracted from the solution and are encapsulated in the coacervate. An encapsulated non enveloped virus is thermally stabilized. Coacervates could help prevent the cold storage problem seen not only in rural parts of Africa but is also a very real problem here in rural parts of America.
By comparing the surface charge of viruses and how they interact with complex polyelectrolytes, we can use the CFM method to predict future interactions and hopefully design coaservate systems with less experimental work needed.
Bio: Xue is currently a PhD candidate and has been working on her PhD project since 2015 fall. She did a co op internship with Genentech in South San Francisco in summer and fall 2016. She has published 5 peer reviewed journal articles from her graduate work and presented her research work in more than 10 regional and national conferences.
Friday, March 1, 2019 at 1:00 p.m.
Chemical Sciences and Engineering Building, 211
1400 Townsend Drive, Houghton, MI 49931