Autonomous parvoviruses encode at least two nonstructural
proteins, NS1 and NS2. While NS1 is linked to important nuclear processes required for viral replication, much less is known about the role of NS2. Specifically, the function of canine parvovirus (CPV) NS2 has remained undefined. Here we have used proximity-dependent
biotin identification (BioID) to screen for
nuclear proteins that associate with CPV NS2. Many of these associations were seen both in noninfected and infected cells, however, the major type of interacting
proteins shifted from nuclear envelope
proteins to
chromatin-associated
proteins in infected cells. BioID interactions revealed a potential role for NS2 in
DNA remodeling and damage response. Studies of mutant viral genomes with truncated forms of the NS2
protein suggested a change in host
chromatin accessibility. Moreover, further studies with NS2 mutants indicated that NS2 performs functions that affect the quantity and distribution of
proteins linked to DNA damage response. Notably, mutation in the
splice donor site of the NS2 led to a preferred formation of small viral replication center foci instead of the large coalescent centers seen in wild-type
infection. Collectively, our results provide insights into potential roles of CPV NS2 in controlling chromatin remodeling and DNA damage response during parvoviral replication.