Role of Litopenaeus vannamei Yin Yang 1 in the Regulation of the White Spot Syndrome Virus Immediate Early Gene .

Yin Yang 1 (YY1) is a multifunctional zinc finger transcription factor that regulates many key cellular processes. In this study, we report the cloning of YY1 from shrimp (LvYY1). This study shows that LvYY1 is ubiquitously expressed in shrimp tissues, and knockdown of LvYY1 expression by double-stranded RNA (dsRNA) injection in white spot syndrome virus (WSSV)-infected shrimp reduced both mRNA levels of the WSSV immediate early gene as well as overall copy numbers of the WSSV genome. The cumulative mortality rate of infected shrimp also declined with LvYY1 dsRNA injection. Using an insect cell model, we observed that LvYY1 activates expression, and a mutation introduced into the promoter subsequently repressed this capability. Moreover, reporter assay results suggested that LvYY1 is involved in basal transcriptional regulation via an interaction with TATA-binding protein (LvTBP). Electrophoretic mobility shift assay (EMSA) results further indicated that LvYY1 binds to a YY1-binding site in the region between positions -119 and -126 in the promoter. Chromatin immunoprecipitation analysis also confirmed that LvYY1 binds to the promoter in WSSV-infected shrimp. Taken together, these results indicate that WSSV uses host LvYY1 to enhance expression via a YY1-binding site and the TATA box in the promoter, thereby facilitating lytic activation and viral replication. WSSV has long been a scourge of the shrimp industry and remains a serious global threat. Thus, there is a pressing need to understand how the interactions between WSSV and its host drive infection, lytic development, pathogenesis, and mortality. Our successful cloning of YY1 (LvYY1) led to the elucidation of a critical virus-host interaction between LvYY1 and the WSSV immediate early gene We observed that LvYY1 regulates expression via a consensus YY1-binding site and TATA box. LvYY1 was also found to interact with TATA-binding protein (LvTBP), which may have an effect on basal transcription. Knockdown of LvYY1 expression inhibited transcription and subsequently reduced viral DNA replication and decreased cumulative mortality rates of WSSV-infected shrimp. These findings are expected to contribute to future studies involving WSSV-host interactions.