H is for helper: granzyme H helps granzyme B kill adenovirus-infected cells.

It is commonly held that the various granzymes (lethal proteases produced by cytotoxic lymphocytes) utilize their different substrate preferences to bring about various forms of target cell death. Although a considerable body of evidence supports this view, it has now become clear that human granzyme H could have evolved a proteolytic specificity that both interferes directly with adenovirus replication and prevents the virus from blocking the potent pro-apoptotic activity of granzyme B.