The Kaposi's sarcoma-associated herpesvirus viral genome packaging accessory factor ORF68 forms cytoplasmic puncta...

Assembly of Kaposi's sarcoma-associated herpesvirus (KSHV) virions is dependent on ORF68, a viral genome packaging accessory factor of unknown function. We used confocal fluorescence imaging to monitor ORF68 localization throughout the KSHV lytic cycle. ORF68 localizes to nuclear viral replication compartments, the site of viral genome packaging. Unexpectedly, ORF68 also localized to cytoplasmic puncta. Using proximity labeling mass spectrometry during infection, we identified ORF68 interaction partners, including the viral tyrosine kinase ORF21. We show that ORF21 colocalizes with ORF68 in cytoplasmic puncta and draws ORF68 to the cytoplasm during infection. This interaction is mediated by the disordered N-terminal region of ORF21. We propose that ORF68 possesses a novel secondary function independent from virion assembly.