The Influenza B virus nucleoprotein (NP) is a highly conserved ~560 amino acid RNA-binding protein that encapsidates viral RNA to form ribonucleoprotein (RNP) complexes essential for viral replication, transcription, and assembly. NP contains nuclear localization and export signals that enable RNP trafficking through the host nucleus, a critical step in the viral life cycle. Owing to its limited antigenic drift, Influenza B NP is a valuable target for broad viral detection across lineages and for surveillance applications. NP is also under active investigation as a vaccine antigen capable of eliciting cross-reactive immunity in next-generation influenza B vaccines. Although not a direct neutralization target, NP remains indispensable for influenza B diagnostics, mechanistic virology studies, and vaccine research. Catalina provides stringently validated Influenza B NP antibodies with high sensitivity and specificity, supporting reliable and reproducible research outcomes.