LRPAP1 and arthritic joint disease: The abundant plasma α2M protein (240 ~ 290 mg/100 mL in adult’s blood), a natural LRPAP1 inhibitor that is generated in the liver and involved in the clearance of the amyloid-beta peptide in the brain and reduction of cartilage degrading factors,51–53 is an FDA-approved drug for treating arthritis and other orthopedic problems.54 We showed promising antiviral effects of α2M at dosages within the biosafety range (<1.5 mg/100 ml) challenged by both DNA and RNA viruses.