Dittmer, D. | bioRxiv Science

bioRxiv2026

Kaposi Sarcoma herpesvirus reactivation and replication are dispensable for cell-lineage specific tumorigenesis in whole genome transgenic mice

Herpesvirus reactivation and replication depend on an ordered cascade of gene expression. The viral immediate-early replication and transcription activator protein (Rta) is necessary and sufficient to initiate this process. For Kaposi sarcoma herpesvirus (KSHV), Rta-interacting and Rta-regulated proteins are thought to contribute to cellular transformation. Using a novel, whole-genome transgenic mouse model, we show that KSHV tumorigenesis is independent of Rta in vivo. Rta-deleted, KSHV bacmid transgenic (tgKSHV{Delta}Rta) mice developed latency-associated nuclear antigen (LANA)-positive vascular sarcomas with the same endothelial cell-lineage composition and transcriptional profile as human Kaposi sarcoma (KS). The viral miRNAs were expressed in the tumors, as were all canonical latency and the K1 and K15 oncogenes. Importantly, this system is the first to model both KS and lymphoma, reflecting the development of both malignancies observed in KSHV-infected individuals. These results separate virus replication from KS tumorigenesis, which can proceed independently so long as the virus genome is maintained in a susceptible cell. SignificanceKaposi sarcoma (KS) is the most common cancer in people living with HIV worldwide. Like all herpesviruses, KS-associated herpesvirus (KSHV) has a latent and lytic phase. Hitherto, viral lytic genes are thought to play a role in KS. The KSHV replication and transcription activator (Rta) is both necessary and sufficient for reactivation and lytic viral replication, but Rta was not required for vascular tumor development in a whole virus genome mouse model. This new tgKSHV{Delta}RTA mouse model separates virus replication from viral tumorigenesis and defines a minimal set of viral oncogenes. This model enables mechanistic studies in vivo, and treatment modalities to be evaluated within a complete immune and stromal microenvironment.

Cancer Biology↗

bioRxiv2020

High-density amplicon sequencing identifies community spread and ongoing evolution of SARS-CoV-2 in the Southern United States

SARS-CoV-2 is constantly evolving. Prior studies have focused on high case-density locations, such as the Northern and Western metropolitan areas in the U.S. This study demonstrates continued SARS-CoV-2 evolution in a suburban Southern U.S. region by high-density amplicon sequencing of symptomatic cases. 57% of strains carried the spike D614G variant. The presence of D614G was associated with a higher genome copy number and its prevalence expanded with time. Four strains carried a deletion in a predicted stem loop of the 3 untranslated region. The data are consistent with community spread within the local population and the larger continental U.S. No strain had mutations in the target sites used in common diagnostic assays. The data instill confidence in the sensitivity of current tests and validate "testing by sequencing" as a new option to uncover cases, particularly those not conforming to the standard clinical presentation of COVID-19. This study contributes to the understanding of COVID-19 by providing an extensive set of genomes from a non-urban setting and further informs vaccine design by defining D614G as a dominant and emergent SARS-CoV-2 isolate in the U.S.

microbiology↗