Study On Monoclonal Antibodies Against Coxsackievirus A Group 16

Hand,foot and mouth disease?HFMD?is a common infectious disease among infants and young children,which is widely prevalent in the world.Coxsackievirus A group 16?CV-A16?is one of the main pathogens of HFMD,which has caused many outbreaks of HFMD in Asia-Pacific region in recent years.CV-A16 infection can cause herpes in the hands,feet and mouth,pharyngitis,cheek inflammation,aseptic meningitis and other symptoms.Serious cases can present myocarditis,pneumonia and even death.However,there is no specific therapeutic drug and vaccine for HFMD caused by CV-A16 infection.Monoclonal antibodies are widely used in clinical diagnosis,treatment and vaccine evaluation because of their specificity and low toxicity.A total of 28 CV-A16 monoclonal antibodies?5 neutralization monoclonal antibodies and 23 non-neutralization monoclonal antibodies?were collected in this study.One neutralization monoclonal antibody NA11F12 and non-neutralization monoclonal antibody MAb 19 were screened out.The results showed that NA11F12 had high specificity and could bind and neutralize CV-A16 strains of subtypes A,B1,B2 and C.NA11F12 can play a protective role in vivo,and the protective effect is dose-dependent and time-dependent.Newborn BALB/c mice were challenged intraperitoneally?i.p.?with BJCA08/CV-A16?GenBank no.JXE81738?54CCID₅₀/mouse,and 0.0042 ug/g of NA11F12 could protect 50%of suckling mice at day 1 post-infection.At 4 days post-infection,10 ug/g NA11F12 could protect 100%of suckling mice.At 5,6 and 7days after challenge,the survival rates of mice were 80%,60%and 20%respectively.Pathological results showed that NA11F12 could prevent CV-A16 replicating in the heart,brain and leg muscles of suckling mice,thus preventing CV-A16-mediated inflammation.Using peptide scanning technology,we found that the epitope of NA11F12 was GDPIADMIDQTV?1-12aa?located on CV-A16 VP1 region,which could affect the release of viral RNA.Neutralizing antibodies are important indicators of anti-viral infectivity and evaluation of vaccine effectiveness,but non-neutralizing antibodies also could play protective effects.Non-neutralization MAb19 can cross-bind different subgenotypes of CV-A16 strain.MAb19 can pretect sulking mice attacked by BJCA08/CV-A16.The protective effect is related to the dose of monoclonal antibody.The lethal infection dose of BJCA08/CV-A16 attack BALB/c suckling mice,3.65 ug/g of MAb19 can protect 50%of suckling mice at day 1 post-infetion.Pathological results showed that MAb19 could prevent CV-A16 replication in the heart,brain and leg muscles of suckling mice and CV-A16-mediated inflammation.The epitope of MAb19 was ENSHPPY?142-148aa?identified by Phage Display.Further studies on the protective mechanism showed that MAb19 protects CV-A16 by promoting macrophage phagocytosis.In this study,the neutralization monoclonal antibody NA11F12 had a good protection effect.A neutralization epitope of NA11F12 was found by peptide scanning,which was located in 1¹2aa of VP1 region.Non-neutralization MAb19 also have protective effects.The protective mechanism is relying on ADCP,and the epitope of MAb 19 is located on 142¹48aa of VP2.These results provide a basis for the development of CV-A16 vaccine and diagnosis and therapy of CV-A16.