VZV ORF19 encodes a large, N-terminal subunit 1 of the viral ribonucleotide reductase, which together with the small subunit, encoded by the VZV ORF 18, forms the ribonucleotide reductase holoenzyme complex (RNR). RNR acts as a key enzyme that catalyzes the reductive synthesis of deoxyribonucleotides from corresponding ribonucleotides, thus providing precursors for viral DNA replication in non-dividing cells, as well as enabling reactivation of the virus in latently infected cells. Our anti-VZV ORF19 antibody VZ 19N.01 works in ELISA (on immunogen), and each LOT is validated for Western blot (of VZV infected cell lysates), where it specifically recognizes a protein species of ~90 kDa, which corresponds well to the predicted size of 86.8 kDa protein encoded by the VZV ORF 19 (described in J Virol. 2013 Jun;87(12):6943-54.).