Establishment of the first WHO International Standard for antiserum to Respiratory Syncytial Virus: Report of an international collaborative study.

Respiratory Syncytial Virus (RSV), a leading cause of lower respiratory tract illness, has been a focus of vaccine development efforts in recent years. RSV neutralisation assays are particularly useful in the evaluation of immunogenicity of RSV vaccine candidates. Here we report a collaborative study that was conducted with the aim to establish the 1st International Standard for antiserum to RSV, to enable the standardisation of results across multiple assay formats. Two candidate standards were produced from serum samples donated by healthy adult individuals. 25 laboratories from 12 countries, including university laboratories, manufacturers/developers of RSV vaccines and public health laboratories, participated in the study. The study samples comprised the two candidate standards, NIBSC codes 16/284 and 16/322, naturally infected adult sera, age stratified naturally infected paediatric sera, sera from RSV vaccine clinical trials in maternal and elderly subjects, a monoclonal antibody to RSV (palivizumab), two cotton rat serum samples and samples from the BEI Resources panel of human antiserum and immune globulin to RSV.