Plant virus-like particles

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Plant virus-like particles as vehicles for therapeutic antibodies

New Delhi, May 20 (By ISW):  Monoclonal antibodies are those that originate from identical immune cells having a common origin. They are highly effective, non-toxic and can specifically target diseased cells, and are therefore used in immunotherapy to treat diseases such as psoriasis, cancer and autoimmune disorders. However, as antibodies are unable to cross the cell membrane, they have mainly been used against antigens present on the surface of cells. Delivering such therapeutic antibodies into a cell to target antigens present inside requires a vehicle that can cross the cell membrane. Virus-Like Particles (VLPs) have this ability. VLPs have only the structural components of a virus but not the genetic material, which makes them non-infectious. According to a press note issued by the Indian Institute of Science (IISc), Now, researchers at the Institute have developed a VLP of a plant virus called the Pepper vein banding virus (PVBV) to use as a possible vehicle to deliver antibodies into a cell. These VLPs can enter mammalian cells as well, despite being of plant origin. Previous research by the group has shown that plant VLPs that are spherical can be used to deliver antibodies. In a new study, published in the Archives of Virology, they have shown this ability in a rod-shaped VLP. This rod-shaped VLP has an added advantage of a large aspect ratio, due to which its surface has a greater number of regions that antibodies can bind to. This allows the rod-shaped VLPs to carry more antibodies than spherical VLPs. The researchers genetically engineered the PVBV VLPs by adding the antibody-binding B domain of a protein called Protein A from Staphylococcus aureus bacteria to an exposed region of the coat protein of the VLP. The resultant is called a chimeric VLP. This chimera, when exposed to the antibodies that need to be transported, can recognize and bind to them to form a stable complex. “The interesting finding that we have shown is that these particles [only when] assembled can enter [the cell], and not their subunits,” says Prof. H S Savithri, corresponding author of the new paper and NASI Senior Scientist at the Department…