DNA-binding protein that plays a critical role in nucleoid compaction, genome replication and DNA replication and transcription (By similarity). Binds to both ssDNA and dsDNA with a binding site covering about 15 nucleotides (By similarity). Displays DNA-supercoiling activity only when associated with the viral DNA topoisomerase 2 (By similarity). Stilbene derivatives SD1 and SD4 disrupt the binding between pA104R and DNA and inhibit the viral replication in primary alveolar macrophages. Homodimer. Found in association with viral nucleoid. Expressed in the late phase of the viral replicative cycle. Host antibody response against A104R protein is higher in asymptomatic than in chronically infected hosts. Belongs to the bacterial histone-like protein family.