Human respirovirus 3 neutralizing antibody escape mutants and their fitness

The respirovirus human parainfluenza virus type 3 (HPIV3) is a leading cause of illness in pediatric, elderly, and immunocompromised populations, yet there are no vaccines or therapies available. Neutralizing antibodies (nAb) are an important new therapeutic strategy, but the evolution of the virus in response to nAb treatment and the associated fitness costs under different conditions must be measured.