Effect of Preexisting Serum and Mucosal Antibody on Experimental Respiratory Syncytial Virus (RSV) Challenge and Infection of Adults.

We studied preexisting respiratory syncytial virus (RSV)-specific serum and nasal antibodies and their correlation with infectivity, viral dynamics, and disease severity in a human experimental infection model. Higher preinoculation serum neutralizing antibody titers and nasal immunoglobulin (Ig) A predicted lower infectivity and lower measures of viral replication. However, once individuals were infected, no significant protective effect of preexisting antibodies was seen. Lack of correlation between serum and mucosal antibodies was observed, implying that they are independent co-correlates of protection against RSV infection. We suggest that protection from RSV infection is a function of a complex interplay between mucosal and serum humoral immune responses.