DIVISION OF IMMUNOLOGY & INFECTIOUS DISEASES

Research

Clinical

Clinical research activities within the division are focused on epidemiology and clinical virology. All physicians participate in antiviral clinical trials conducted by the Collaborative Antiviral Study Group funded by the National Institute of Allergy and Infectious Diseases. Current studies include the following:

  • "A Placebo-Controlled Phase III Evaluation of Suppressive Therapy with Oral Acyclovir Suspension Following Neonatal Herpes Simplex Virus Infections Involving the Central Nervous System" (CASG #103)
  • "A Placebo-Controlled Phase III Evaluation of Suppressive Therapy with Oral Acyclovir Suspension Following Neonatal Herpes Simplex Virus Infections Limited to the Skin, Eye, and Mouth" (CASG #104)
  • "A Double-Blind, Placebo-Controlled, Virologic Efficacy Trial of Pleconaril (VP 63843) in the Treatment of Neonates with Enteroviral Sepsis Syndrome" (CASG #106)
  • "Genetics of Infection and its Relationship with Cardiovascular Disease Risk" (Dr. Leach in collaboration with Southwest Foundation for Biomedical Research) (R01 HL080149-01A2)

Other active clinical research projects include: "Febrile Syndromes in the Lower Rio Grande Valley: The Role of Dengue, Leptospirosis, and Murine Typhus as Regional Re-Emerging Infections" (Dr. Leach); and "The Epidemiology of Fecally-Orally Transmitted Infections in Health Care Workers along the Texas-Mexico Border" (Dr. Leach)

Research photo


Basic and Translational Research

Overview of Research Program: Dr. Gao heads the Tumor Virology Program, which is also a research program in Children's Cancer Research Institute (CCRI). For more information on CCRI and the Tumor Virology Program, please visit http://ccri.uthscsa.edu. The primary focus of Dr. Gao's research program is on tumor viruses with emphasis on Kaposi's sarcoma-associated herpes virus (KSHV), also known as human herpes virus 8 (HHV8), the most recently discovered human herpes virus. KSHV has been etiologically associated with the development of Kaposi's sarcoma (KS), a vascular spindle cell disease frequently occurring in persons with AIDS, and several other malignancies including primary effusion lymphoma (PEL) and a subset of multicentric Castleman's disease (MCD). Dr. Gao's laboratory is to study the epidemiology and molecular mechanism of KSHV-related pathogenesis in an effort to provide a biologic basis for preventative and therapeutic purposes.

Cell model for KSHV infection

  1. Cell Model and Genetic Manipulation System - Studies of KSHV have been impeded because of the lack of an efficient infection system. Consequently, the development of a genetic manipulation system is elusive. Over 90 KSHV genes or ORFs have been identified, and many of them have been cloned and examined in tissue culture, however, their functions in KSHV infection and the pathogenesis of KSHV-related malignancies remain unclear. To facilitate KSHV studies, we have recently developed a genetic approach to isolate infectious KSHV. The entire KSHV has been cloned into bacteria artificial chromosome (BAC) and reconstituted in mammalian cells. Cells infected by the recombinant KSHV (BAC36) can be efficiently induced into lytic replication to produce highly infectious virions. BAC36 virions efficiently infect human primary endothelial cells (>90%) and transform them into Kaposi's sarcoma-like vascular spindle cells. This cell model recapitulates both the viral and cellular aspects of KSHV infection in KS tumor cells. Thus, we have established a cell model and an efficient bacteria-mammalian shuttle system for KSHV infection, replication, cellular transformation and genetic analysis.

    Characterizations of KSHV infection and replication have mostly been performed with KSHV-infected PEL cell lines, for which appropriate controls are difficult to identify for some experiments. Most of these studies have been restricted to the examination of viral latency and reactivation. Only a limited number of studies have investigated KSHV primary infection so far; however, they have been carried out using systems that have inefficient viral infection. Our cell model is ideal for defining the virology and cellular biology of KSHV primary, latent and lytic infection, and cellular transformation. Currently, we are determining the expression patterns of viral and cellular genes during KSHV infection and replication in human primary endothelial cells using a KSHV microarray recently developed in our laboratory and Genechips from Affymetrics in combination with real-time RT-PCR technology. Simultaneously, we are also examining the alterations of cellular phenotypes including cell adhesion and migration, cellular proliferation, cell cycle progression, and apoptosis. These studies should provide insight into the molecular events of KSHV latent and lytic replication, and viral regulation of cellular pathways in human primary endothelial cells, and further define the cell model for the examination of KSHV infection, replication, and transformation.

    KSHV infection converts human primary endothelial cells into Kaposi's sarcoma-like spindle cells
    KSHV infection converts human primary endothelial cells into Kaposi's sarcoma-like spindle cells

  2. Delineation of KSHV Transformation Genes

    - KSHV encodes several genes that are oncogenic, and/or promote cell growth and survival; however, their functions in KSHV-induced malignant transformation remain unclear. Using the genetic manipulation system, we have generated a library containing mutants of >95% KSHV genes. With these mutants, we are attempting to identify viral genes and their functional domains that are essential for KSHV cellular transformation of human primary endothelial cells. Once KSHV transformation genes are identified, we will further define signals transduced and cellular pathways targeted by these genes. These studies will define KSHV genes and their domains, and altered cellular pathways that are critical for KSHV malignant transformation, thus lead to a better understanding of KSHV-related pathogenesis.

    LNA-KLIP1 interaction in vivo
    LNA-KLIP1 Interaction in vivo

  3. Functional studies of KSHV latent nuclear antigen (LNA, LANA, ORF73) - LNA is the most immunodominant major latent nuclear antigen discovered when we developed KSHV serologic assays. LNA encoded by ORF73 has since been shown to be a multi-functional viral protein that maintains the stability of viral episomes and regulates viral and cellular gene transcriptions. We have recently identified an array of LNA-interacting proteins by yeast-two hybrid screen. One of such protein, named LNA-interacting protein 1 (KLIP1), is a novel nuclear protein. Primary characterization has demonstrated that KLIP1 is a potent transcriptional repressor and its expression is cell cycle dependent. Several other identified LNA-interacting proteins are also involved in the regulation of cellular gene transcription. We are currently characterizing the biologic function of KLIP1 and the significance of the interactions of LNA with these cellular proteins.

  4. We have generated LNA stably-transfected HeLa cell lines and examined the global regulation of cellular gene expression by LNA using microarray. A total of 45 cellular genes had significant changes in expression levels, and some of them have been confirmed by Northern-blot analysis and real-time RT-PCR. Besides genes that are involved in cell cycle progression and apoptosis, LNA also regulates the expression of genes that are involved in other signaling pathways. Studies are ongoing to examine the upstream and downstream regulation of these genes.

  5. We have also identified a hypervariable internal repeat domain (IRD) of LNA. Based on the variability of IRD, we have developed a novel genotyping technique, named KVNAtyping, that can be used for the characterization of LNA molecular polymorphism and molecular epidemiologic studies of KSHV (see below). We are determining the correlation of IRD variations with LNA functions.