Plant VLPs as Vehicles for Antibodies – Pepper Vein Banding Virus (PVBV)
Antibodies that originate from identical immune cells having a common origin are the monoclonal antibodies and they are used in immunotherapy to treat diseases such as autoimmune disorders, cancer, and psoriasis, as they can specifically target diseased cells, and are non-toxic and highly effective. However, these antibodies have been used mainly against antigens present on the surface of cells as they are unable to cross the cell membrane.
To target antigens present inside the cell, a vehicle that can cross the cell membrane is required to deliver such therapeutic antibodies into the cell. Virus-Like Particles (VLPs) have this ability and they are non-infectious as they do not have the viral genetic material and have only the structural components of a virus.
The Indian Institute of Science (IISc) released a press note, according to which, to deliver antibodies into a cell, a VLP of a plant virus called the Pepper vein banding virus (PVBV) has been developed to be a possible vehicle by the researchers at the Institute. Despite being of plant origin, these VLPs can enter mammalian cells also.
To deliver antibodies, the group had shown that spherical plant VLPs can be used, in previous research. In this new study, they have shown that a rod-shaped VLP to have this ability. The Archives of Virology published this study. This rod-shaped VLP has a greater number of regions that antibodies can bind to as it has a large aspect ratio, and this is an added advantage of this rod-shaped VLP. Due to this, more antibodies than spherical VLPs can be carried by the rod-shaped VLPs.
To an exposed region of the coat protein of the VLP, the antibody-binding B domain of a protein called Protein A from Staphylococcus aureus bacteria was added and in this way, the PVBV VLPs was genetically engineered by the researchers. The resultant is called a chimeric VLP. This chimera can recognize and bind to the antibodies to form a stable complex when exposed to the antibodies that need to be transported.
At the Department of Biochemistry, IISc, Bengaluru, NASI Senior Scientist, and the corresponding author of the new paper, Prof. H S Savithri says, “These particles can enter the cell only when assembled and not their subunits, and this is the interesting finding that we have shown. This is due to the membrane receptors recognizing a scaffold formed by the assembled particles, something that does not happen when they are individual protein subunits. These antibody-bearing chimeric VLPs can neutralize the target antigen as it can enter mammalian cells and deliver the antibody inside. It can be checked if the VLPs are delivering the antibodies to the right location as the researchers chemically combined fluorescent molecules to the surface of the VLPs.”
The advantages of using biodegradable, non-infectious, and rod-shaped plant VLPs are proved in the study. To test the delivery of antibodies to specific cells, such as cancer cells, there can be further research conducted on animal models. For the treatment of diseases such as neurodegenerative disorders and cancer, this can have immense therapeutic potential.
Plant VLPs as Vehicles for Antibodies