INTRANASAL MONOCLONAL IGA ANTIBODY TO RESPIRATORY SYNCYTIAL VIRUS PROTECTS RHESUS-MONKEYS AGAINST UPPER AND LOWER RESPIRATORY-TRACT INFECTION

Respiratory syncytial virus (RSV), the major cause of lower respirator y tract disease in infants, is thought to infect the upper airways bef ore spreading to the lower respiratory tract. A rhesus monkey model of RSV infection after upper airway inoculation was used to test the pro tective effect of intranasal treatment with HNK20, a mouse monoclonal IgA antibody against RSV F glycoprotein. HNK20 was administered once d aily for 2 days before RSV challenge and 4 days after challenge. Treat ment with 0.5 mg/kg HNK20 reduced viral shedding in the nose, throat, and lungs by 3-4 log(10)/ml (P less than or equal to .002). All monkey s developed RSV neutralizing antibody in serum, even in the absence of detectable viral replication. Neutralizing concentrations of monoclon al antibody remained in nasal secretions for >1 day after treatment. T hese results suggest that nose-drop application of monoclonal antibody could provide convenient and effective protection against RSV infecti on in human infants at risk of severe lower respiratory tract disease.