Emerging methods that couple mass spectrometry of fragments generated from isolated proteins with database searching offer a powerful means of identifying proteins and the genes that encode them. We have applied this technology to a herpesvirus, channel catfish virus, and have identified 12 genes, 11 viral and 1 cellular, that encode 16 principal structural proteins. These proteins include three components of the mature capsid and a potential scaffolding protein present in immature capsids, three protein kinases, a C3HC4 zinc-binding protein and cellular actin located in the tegument, and a multiply hydrophobic protein associated with the envelope.