Microorganisms often use cell surface polysaccharides to build expanded barriers to prevent their host's defense mechanisms . In this study, it was found that ORF7a can synthesize lipopolysaccharide (LPS). After a lot of LPS bound to the infected cell's surface, LPS was equivalent to the infected cell's shield, making the SARS-COV-2 infected cell's outer membrane like a "cell wall". Infected cells significantly reduced cytotoxic T cells and NK cells' ability to destroy the infected cell membrane (such as perforation).