Hongwei Yu, Ph.D.
Associate Professor and Cluster Coordinator
Department of Biochemistry and Microbiology
Joan C. Edwards School of Medicine
Marshall University
One John Marshall Drive
Huntington, WV 25755
Research Clusters: Infectious and Immunological Diseases; Toxicology and
Environmental Health Sciences
Phone: (304) 696-7356; Fax: (304) 696-7207
E-mail: yuh@marshall.edu
Office: BBSC 435-R
Laboratories: BBSC 428 and 429
Research Overview
Two projects are on-going in the Yu laboratory.
Genetic regulation of biofilm formation
Many bacteria in nature and disease aggregate forming microcolonies covered with a matrix of glycocalyx. The formation of such a conglomerate structure, also known as a biofilm, is one of the leading causes for refractory pneumonia in astronauts during a long-term mission in space, and in patients with cystic fibrosis. Biofilm formation requires participation of a number of coordinately-expressed genes. We are interested in what/how genes regulate transition from free floating to surface-attached cells, and what/how environmental signals induce genotypic changes causing the overproduction of an exopolysaccharide. The model organism is Pseudomonas aeruginosa, a ubiquitous, gram-negative bacterium capable of displaying two distinct phenotypes: nonmucoid or mucoid colony morphology. The genome of a reference strain P. aeruginosa PAO1 has been completely sequenced. However, the majority of the genes remain unknown. The goal of this project is to discover the anti-biofilm targets using functional genomic approaches. The specific aims are i) to identify genes involved in biofilm formation and control of mucoid/nonmucoid conversion, and ii) to elucidate molecular mechanisms governing these morphological changes. By participating in this project, the perspective students and postdoctoral fellows will tackle the issue of genetic regulation using approaches such as cloning, complementation, phage transduction, gene knockout, transcriptional analysis, transposon mutagenesis, PCR, real-time PCR, genomic analysis using PFGE, Southern blot, DNA sequencing, protein overexpression and purification, PAGE, functional analysis of proteins, and Western blot. In addition, imaging techniques utilizing a green fluorescent protein or a bioluminescent system are used. This project is being supported by NASA.
Genetic basis of bacterial lung infections in mice
Most of bacterial lung infections initiate with the colonization of the upper respiratory tract. Aspiration of oropharyngeal secretions containing colonizing bacteria deep into the lung allows for the establishment of lower respiratory tract infections. Pneumonia in cystic fibrosis is characterized by infections in the lower respiratory tract, which is otherwise a sterile environment. We are using an inhalation exposure system for the deposition of the airborne pathogens into distal airways of the mouse lungs, causing the establishment of acute pneumonia for the identification of the susceptibility gene. This model is being utilized to perform forward and reverse genetic analysis to map and study the genes that confer increased susceptibility to lung colonizations by pathogens, P. aeruginosa, Staphylococcus aureus and Klebsiella pneumonia. The goal of this project is to better understand the etiology of lung infections in conjunction with genetic defects. The specific aims are i) to locate a mouse susceptibility locus to bacterial lung infections; ii) to study the innate immunity against bacterial lung colonization; and iii) to identify the genes from the P. aeruginosa genome that alter the susceptibility status in mice. The techniques used for this project include plate counts, lung histopathology, cytokine analysis, PCR, real-time PCR, microarray, laser capture microdissection, transposon mutagenesis, and immunohistochemistry. Furthermore, we plan to label bacteria with a bioluminescent or fluorescent marker for in vivo detection and tracking. This project is being supported by NIH DK058128 and Cystic Fibrosis Foundation.
Laboratory Personnel
Vonya Eisinger, Research Technician
Christopher Hearn, Ph.D. Student
Dongru Qiu, Postdoctoral fellow
T. Ryan Withers, Ph.D. Candidate
Hongwei D. Yu, PI
Selected publications
1. Head, N. E. and H. Yu. 2004. Cross-sectional analysis of clinical and environmental isolates of Pseudomonas aeruginosa: Biofilm formation, virulence and genome diversity. Infect. Immun. 72: 133-144.
2. Yu, H. and N. E. Head. 2002. Persistent infections and immunity in cystic fibrosis. Front Biosci. 7: d442-457.
3. Yu, H., S. Z. Nasr, and V. Deretic. 2000. Innate lung defenses and compromised Pseudomonas aeruginosa clearance in the malnourished mouse model of respiratory infections in cystic fibrosis. Infect. Immun. 68: 2142-2147.