Investigation of viral and host determinants of gammaherpesvirus pathogenesis

Division Of Basic Sciences - Nci

Investigators

Linked publications & trials

Abstract

(Aims 1-2) STAT3 activation is associated with gammaherpesvirus latency and cancer in cell culture systems, but the role of two KSHV genes that activate STAT3 in vivo is not well-defined. My lab is examining the impact of the KSHV vIL-6 and KSHV vGPCR on chronic infection in vivo. To do this, we have constructed recombinant murine gammaherpesviruses that expresses these KSHV genes in disease-relevant cell types such as B cells in the context of murine infection. (Aim 3) My lab has also generated a recombinant murine gammaherpesvirus that expresses the KSHV K3 and K5 genes in place of the mouse gammaherpesvirus K3 homolog. This will enable us to understand how gammaherpesviruses alter immune molecules on the infected cell surface to modulate the host immune response. (Aim 4) I continue to collaborate with other NIH investigators and clinicians in HAMB to analyze the B cells infected with gammaherpesviruses. We detected a primate gammaherpesvirus in the B cells in the PBMC and lymphoma tissues of common marmosets housed at the NCI. We are examining the phenotype of B cells in HIV-associated primary effusion lymphoma and lymph node material of HIV-infected KSHV-multicentric Castleman disease patients enrolled in HAMB clinical trials. (Aim 5) With regard to the development of tumor models of Kaposi sarcoma, a hallmark tumor of AIDS, I collaborated with clinicians in the HIV and AIDS Malignancy Branch and in the Center for Advanced Preclinical Research (CAPR) and more recently the Laboratory Animal Sciences Program (LASP) of NCI Frederick in more translational projects towards the establishment of patient-derived xenograft models of KS. KS biopsy material from HIV infected patients in the HAMB clinical cohorts has been implanted into immune deficient NSG animals. We find consistent KSHV-infected lymphatic endothelial cell proliferation and expansion in the patient-derived xenografts of skin KS. Lytic viral transcripts increase, along with an increase in KS signature genes such as CXCR4 and proliferation markers. Our findings will be reported in a manuscript under revision for publication. For the patient derived xenografts of anaplastic KS tumors, we have observed rapid tumor growth that maintains the virus through five passages in mice. This past year we have established two more PDX from anaplastic KS tumors that are under expansion for biobanking and molecular analyses. Patient-derived xenograft materials derived from this system that maintain KSHV infection and drive tumors in mice will be a tremendous advancement for the field since there is no way to maintain KSHV+ endothelial cells upon explant and there is no established pre-clinical animal model of Kaposi sarcoma to screen for effective drug interventions of this AIDS-defining cancer. (Aim 6) We have collaborated with NCI colleagues and LASP to establish five PEL cell lines derived from the PEL of three HAMB patients. These new patient-derived PEL were passaged and expanded twice through NSG mice, leading to ascites, spleen and mesenteric mass tumors that harbored the KSHV-infected B cell lymphomas. We will next examine for the viral gene expression profile, transcriptome profile, reactivation and drug susceptibility properties to better understand the heterogeneity of this aggressive type of lymphoma that is often infected with both EBV and KSHV.