Postdoctoral Associates 

Dr. Sara Jones

Ph.D., Baylor College of Medicine, Houston, TX 2008

Beneficial microbes limit disease caused by invading pathogens; however, the mechanisms and genes utilized by beneficial microbes to inhibit pathogenesis are poorly understood. Bacillus subtilis is a spore-forming bacterium present in the gut of mammals and B. subtilis spores have been used to prevent intestinal disease. B. subtilis limits intestinal disease induced by the murine pathogen Citrobacter rodentium, which is genetically similar to the human pathogens enterohemorrhagic and enteropathogenic E. coli. I want to determine the B. subtilis genes required for protection and elucidate the host pathways modulated by B. subtilis. By expanding our current mechanistic knowledge of bacterial protection, we could better utilize beneficial microbes to prevent intestinal disease caused by pathogenic bacteria.

Dr. Yoichi Seki

Ph.D., Biological Sciences, Tokyo University of Science, Japan, 2004

T cells play a central role in the promotion of the effector and regulatory functions in the immunological system, and failures of these functions are cause of various immunological disease. My research goal is clarifying the details of molecular mechanisms of the development and differentiation processes into effector T cell (such as Th1, Th2 and Th17), memory T cells and regulatory T cells. The accumulation of these knowledge will provide us novel point of view to develop the therapeutic strategy for various immune disorders.

Dr. Satoshi Shibata

Ph.D., Department of Life Sciences, Prefectural University of Hiroshima, Japan, 2008

Specific interactions between bacteria and their host are important in both pathogenesis and symbiosis. The Visick Lab is trying to understand mechanisms of symbiotic interactions between the bioluminescent bacterium Vibrio fischeri and the squid Euprymna scolopes at the molecular level. The symbiosis polysaccharide (syp) cluster is involved in biofilm formation that is necessary for symbiotic colonization by V. fischeri. However, little is known about the roles of the 18 syp genes in biofilm formation. Thus, the aim of my study is investigate the roles of these genes in biofilm formation by V. fischeri. We anticipate that this work will promote a deeper understanding of the requirements for symbiotic colonization.

Dr. Mutsumi Yamamoto

Ph.D., Biological Sciences, Tokyo University of Science, Japan, 2006

My research goal is to identify the molecular mechanism by which the immune system maintains its memory. In particular, I am interested in how antigen activation of naive T cells convert naive cells to be memory T cells, which live longer and respond more effectively to the antigen than naive T cells. Currently, studies on memory T cells rely mostly on the cell surface antigen expression that change as the time passes from initial activation. I will use a genetic system that marks T cells that are activated by antigens and follow their fate, localization, surface antigen expression, and gene expressions. This study will provide critical information to understand how immune memory is maintained and will help developing more effective and long lasting vaccines.

Dr. Yougang Zhai

Ph.D., Institute for Viral Disease Control and Prevention, China CDC, China, 2008

Because mucosal tissue is one of the major sites of HIV infection, an effective HIV vaccine must induce both systemic and mucosal immunity to contain virus transmission through hematogenous or sexual pathway. Mucosal immunization can induce both mucosal and systemic immunity, including neutralizing antibodies and cytotoxic T lymphocytes. In Dr. Qiao's Lab, we are trying to develop mucosa vaccines to prevent HIV-1 infection. The overall goal of my study is to develop effective mucosa vaccine(s) for HIV-1. Two approaches will be applied for the vaccine design. Briefly, we will develop chimeric virus-like particles (CVLPs) containing conserved epitopes that can be recognized by HIV-1 broadly neutralizing antibodies. On the other hand, we will also develop pseudovirus vaccine that is comprised of empty viral capsid and foreign plasmid DNA. Eventually, HIV-1 specific immune response(s) induced by either vaccine will be determined. This work will benefit the development of a novel effective mucosal vaccine for HIV-1.

Dr. Ekaterina Semenyuk

Ph.D., Plant Physiology, Timiryazev Institute of Plant Physiology, Moscow, Russia, 2003

Clostridium difficile infection is a devastating gastrointestinal disease and a major problem in hospitals world wide. Complicating treatment is the capacity of the disease to persist in the host after apparently successful antibiotic treatment.
Our central hypothesis is that C. difficile forms abiofilm in the host gastrointestinal tract. C. difficile biofilms could contribute to disease by 1) facilitating attachment of C. difficile to appropriate locations in the colon, 2) resisting host defenses and antimicrobial drugs, 3) accumulating toxin and directing it to host tissues, and 4) by harboring a depot of dormant spores that could facilitate relapsing disease. Understanding C. difficile biofilm structure and mechanisms used by this organism to evade host defenses and therapeutics would greatly facilitate development of novel treatments.

Dr. Vihanga Pahalawatta

Ph.D., Plant Pathology, Washington State University, Pullman, WA, July 2007

Certain bacteria produce highly resistant, dormant cells called spores to survive adverse environmental conditions. Spores are protected by the spore coat, which is composed of over 70 proteins. However, the functions of a majority of these proteins remain unknown. In my project, I am looking at Bacillaceae spores subject to different stress conditions, to identify coat protein genes with high copy numbers correlating with specific environmental stress conditions. My particular focus is on Bacillaceae spores in soils with gradients in soil moisture content and heavy metal contamination. I am developing a quantitative Real-Time PCR- based assay to identify and quantify individual spore coat protein genes within these two environmental gradients. Additionally, I am using high-throughput sequencing to determine the Bacillaceae species distribution in the sampled soils. The correlation between the specific stress and spore coat protein gene copy number will enable us to establish the functional roles of the coat proteins and the contributions of the coat proteins in spore adaptation to environmental stresses.

Dr. Xufang Deng

Ph.D., Shanghai Veterinary Research Institute, CAAS, China, 2011

Coronaviruses cause important human and animal disease with respiratory, gastrointestinal and neurological symptoms. The severe acute respiratory syndrome coronavirus (SARS-CoV) emerged from Guangdong province of China in 2003, which infected more than 8000 people worldwide with 10% mortality, promotes to investigate the viral pathogenesis and to develop antiviral agents. In previous studies of Dr. Baker’ Lab, the Papain-like proteases (PLPs) of coronaviruses have been identified to possess deubiquitinating enzyme, deISGylating enzyme activities and act as IFN antagonism. My research mainly focuses on further elucidating the mechanism of PLpro-mediated evasion of innate immune response. We will determinate the effect of PLPs to disturb the ubiquitination and ISGylation of cellular proteins in mice infected with recombinant Sindbis virus co-expressing ISG15 and PLPs (rSinV-ISG15-PLPs). And we will evaluate the immune response of mice infected by rSinV-ISG15-PLPs or PLPs mutants. This work will further demonstrate the biological functions of PLPs and highlight its significance as a target of developing antiviral drugs.