The plasmid-encoded members of paralogous gene family 52 are dispensable to the enzootic cycle of .

Lyme disease, the leading vector-borne disease in the United States and Europe, develops after infection with bacteria. Transmission of the spirochete from the tick vector to a vertebrate host requires global changes in gene expression that are controlled, in part, by the Rrp2/RpoN/RpoS alternative sigma factor cascade. Transcriptional studies defining the RpoS regulon have suggested that RpoS activates the transcription of paralogous family 52 (PFam52) genes.

Rrp2, a prokaryotic enhancer-like binding protein, is essential for viability of Borrelia burgdorferi.

The Lyme disease spirochete, Borrelia burgdorferi, exists in two diverse niches (i.e., an arthropod tick vector and mammalian host) during its enzootic life cycle.