Epstein–Barr virus enhances genome maintenance of Kaposi sarcoma-associated herpesvirus

Primary effusion lymphoma(PEL) is a B cell lymphoma that is always associated with Kaposi’s sarcoma-associated herpesvirus(KSHV) and in many cases also with Epstein–Barr virus (EBV); however, the requirement for EBV coinfectionis not clear. Here, we demonstrate that adding exogenous EBV to KSHV + single-positive PEL leads to increased KSHV genome maintenance and KSHV latency-associated nuclear antigen (LANA) expression. To show that EBV was necessary for naturally coinfectedPEL, we nucleofectedKSHV + /EBV + PEL cell lines with an EBV-specific CRISPR/ Cas9plasmid to delete EBV and observed a dramatic decrease in cell viability, KSHV genome copy number, and LANA expression. This phenotype was reversed by expressing Epstein–Barr nuclear antigen 1 (EBNA-1) in trans , even though EBNA-1 and LANA do not colocalize in infected cells. This work reveals that EBV EBNA-1 plays an essential role in the pathogenesis of PEL by increasing KSHV viral load and LANA expression.