There are multiple definitions:

1. neutralizing antibody(English)

   • critical contributor to protective responses against most viral infections
   • Virology
   • https://doi.org….ai.2017.01.004

2. "natural" antibody(English)

   • AMR, HAR, NHP, PERV
   • Transplantation, Immunology
   • https://doi.org…science.abo7935