ORF48 is required for optimal lytic replication of Kaposi’s-Sarcoma Associated Herpesvirus

Beatriz Veronese

Graduate Student, Biomedical Sciences Program-Cancer Biology Concentration

Abstract: Kaposi’s Sarcoma-associated herpesvirus (KSHV) causes several human diseases, such as Kaposi Sarcoma, multicentric Castleman’s disease, and primary effusion lymphoma. KSHV sustains lifelong infection by encoding several viral proteins that can downregulate the host immune system and facilitate virus replication. A previous study identified multiple KSHV proteins that function as inhibitors of the cGAS-STING pathway, which is an innate immunity pathway that exerts important antiviral functions. In the present study, we aim to further characterize one of these inhibitors, the KSHV ORF48. Our hypothesis is that ORF48 targets the cGAS/STING pathway to negatively regulate innate immunity and facilitate KSHV replication. We utilized genetic recombination techniques to delete the ORF48 DNA sequence from the KSHV genome, and then generated stable cell lines (iSLK.BAC16 cells) that harbor the mutant version of the virus (lacking ORF48 protein) or the wild-type version (complete KSHV genome). Our results show that ORF48 deletion nearly abolished KSHV replication in iSLK.BAC16 cells, as demonstrated by reduced levels of KSHV lytic gene transcripts, reduced KSHV lytic protein expression, reduced KSHV genome copies, and reduced number of infectious virions. Collectively, our data indicate that ORF48 is critical to optimal KSHV lytic replication. Further mechanistic studies will be performed to assess whether potential ORF48 immune-suppressive roles are essential for lytic replication.

Beatriz Veronese is a doctoral candidate pursuing her Ph.D. in Medical Sciences with a major in Cancer Biology. Her research focuses on dissecting how KSHV proteins subvert the host Immune system to drive its pathogenesis.

Core Standards

SC.912.N.1.4 Identify sources of information and assess their reliability according to the strict standards of scientific investigation.

SC.912.N.1.6 Describe how scientific inferences are drawn from scientific observations and provide examples from the content being studied.

SC.912.N.2.2 Identify which questions can be answered through science and which questions are outside the boundaries of scientific investigation, such as questions addressed by other ways of knowing, such as art, philosophy, and religion.

SC.912.N.2.5 Describe instances in which scientists’ varied backgrounds, talents, interests, and goals influence the inferences and thus the explanations that they make about observations of natural phenomena and describe that competing interpretations (explanations) of scientists are a strength of science as they are a source of new, testable ideas that have the potential to add new evidence to support one or another of the explanations.

SC.912.L.16.5 Explain the basic processes of transcription and translation, and how they result in the expression of genes.

SC.912.L.16.6 Discuss the mechanisms for regulation of gene expression in prokaryotes and eukaryotes at transcription and translation level.

SC.912.L.16.8 Explain the relationship between mutation, cell cycle, and uncontrolled cell growth potentially resulting in cancer.

SC.912.L.16.7 Describe how viruses and bacteria transfer genetic material between cells and the role of this process in biotechnology.


NCI Cancer Center badge