Research Areas

Bacteriology

Our bacteriology program carries out fundamental research on antimicrobial discoveries, host-bacterial interactions, pathogenesis of bacteria and vector-borne bacteria, vector biology, and diagnostics. Research conducted by Drs. Daniel Nelson, Utpal Pal, Sean Riley, Xiuli Yang, and Sandip De aim to understand the human and animal bacteria and disease process caused by bacteria such as Borrelia burgdorferi, Clostridium difficile, Leptospira, Rickettsia, Staphylococcus aureus, Streptococcus, as well as novel vaccine and antimicrobial development using molecular engineering approaches.

The emergence of multidrug-resistant bacteria, new pathogens, and the desire to reduce and eliminate antimicrobial use in agriculture products have open areas to identify and develop alternative antimicrobial therapeutics. Dr. Nelson’s Lab uses multidiscipline approaches to discover peptidoglycan hydrolase enzymes, called endolysins, from bacteriophage and applies them to bacterial pathogens. These enzymes act rapidly on contact to degrade the bacterial cell wall of both human and animal pathogens, resulting in the death of the bacterial cell, such as Staphylococcus aureus, Streptococcus, etc. To improve endolysins function, Dr. Nelson’s lab is engineering and producing endolysins with more desirable reliability and enhanced properties. 

The bacterium Borrelia burgdorferi causes Lyme disease. It is transmitted to humans through the bite of infected black-legged ticks. Dr. Pal has established research programs in areas of arthropod-borne pathogens, particularly focusing on Borrelia burgdorferi.  His research aims to understand the biology of both bacteria and tick vector, host-pathogen interaction and pathogenesis. The ultimate goals are to develop novel diagnostic methods, vaccines, and therapeutic strategies. Dr. Pal’s research has identified a panel of borrelial infection-inducible tick proteins that are essential for bacterial persistence. His current studies attempt to explore whether these tick antigens can be used as targets for developing preventive strategies to prevent infection. The work of Dr. Yang, in Dr. Pal’s group, is studying the role of host factors in the pathogenesis of Borrelia burgdorferi infections and developing novel intervention strategies for bacterial transmission. Dr. Sandip De, in Dr. Pal’s group, is studying epigenetic regulation of host, vector, and microbial genes relevant to tick-borne infections.

Leptospirosis is a disease caused by infection with Leptospira. The infection from animals to humans occurs when a wound in the skin encounters water or soil contaminated with animal urine Dr. Pal's research is developing RNA-detection based assays for diagnosing human leptospirosis. These assays could also improve the diagnostics of animal leptospirosis.

The bacterium Rickettsia rickettsii causes Rocky Mountain spotted fever (RMSF), the most common rickettsial infection in the USA. Rickettsial pathogens are usually spread to people through the bites of ticks, mites, fleas, or lice that have previously fed on infected animals. Dr. Riley focuses on developing our understanding of the host-pathogen interaction between obligate intracellular Rickettsia, mammalian hosts, and arthropod vectors. Specific investigations include: deciphering the interactions between Rickettsia and innate immunity, hijacking the molecular interactions between bacteria and host cells to develop therapeutics, employing genomic approaches to find virulence factors that contribute to diseases, and using evolutionary biology to identify promising vaccine candidates.

Epidemiology

In the Department, Drs.  Nathaniel Tablante and Mostafa Ghanem focus on epidemiology. Dr. Tablante is investigating knowledge gaps and risk factors associated with economically important poultry diseases and developing cost-effective, practical strategies to prevent and control them. Dr. Ghanem’s research is in the area of molecular epidemiology of infectious diseases. His research program focuses on the development of advanced molecular typing schemes using next-generation sequencing for typing and epidemiological investigation of Infectious diseases of economic and public health significance. He is interested in harnessing the application of advanced molecular diagnostic and genotyping techniques in surveillance, prevention, and control of infectious diseases to improve the health and wellbeing of humans and animals.

The specific aims of the epidemiology research program include the following: develop novel diagnostic approaches for rapid identification and characterization of bacterial pathogens, advance strain typing schemes for outbreak investigation and routine surveillance, use new tools and approaches to improve the current understanding of different risk factors controlling the emergence, evolution, spread and persistence of bacteria within animal production systems and different environments, and assess different intervention strategies for mitigating the negative impacts of infectious diseases.

Immunology

The immune system, including innate and adaptive immune responses, protects the host against infectious diseases. Our faculty, Drs. Meiqing Shi, Yanjin Zhang, Xiaoping Zhu, understand the basic mechanisms of the immune system and how it controls infectious diseases.

Dr. Shi’s lab is studying intravascular immune responses to Cryptococcus neoformans, molecular mechanisms involved in brain invasion by C. neoformans, dynamic interactions of immune cells with C. neoformans in the brain. The C. neoformans is a fungus that lives in the plants, animals, and soils throughout the globe. People and animals can become infected with C. neoformans after breathing in the small-sized fungus. People who have weakened immune systems, such as AIDS patients, organ transplant recipients, cancer patients, and many others, can be very susceptible to infections. Approximately one million people per year are infected, and about 181,000 people per year will die from this devastating disease.

Innate immunity is a first-line defense against invading pathogens. Interferons are essential components of the innate immunity and play crucial roles in antiviral response. Dr. Zhang’s lab studies the mechanisms of viral antagonism of interferon production and interferon-activated Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling. His lab has discovered that porcine respiratory and reproductive viruses (PRRSV) inhibit the signaling of STAT1, STAT2, and STAT3. His lab also studies karyopherins, which are a group of proteins mediating the nucleocytoplasmic trafficking of numerous proteins including those transcription factors involved in host defense.

The mucous membranes, including respiratory, gastrointestinal, and genital tracts, constitute the largest surfaces of the body and above 90% pathogens that invade the body through these mucosal routes. Nevertheless, the mucosal immune systems are still poorly understood due to their complexity. On one hand, foreign antigens such as food and commensal flora in the mucosa must be tolerated. On the other hand, bacterial toxins and hostile pathogens must be recognized, and their uptake or active intrusion must be prevented. Deregulation of this hemostasis can result in severe disorders, such as chronic inflammation, autoimmune diseases, and decreased immune defense against pathogens. One central question is how the mucosal immune responses are so finely regulated during infection and inflammation. Answering this basic question is the main goal of Dr. Zhu’s research program.

Parasitology

The parasite Trypanosoma brucei (T. brucei) is the cause of a tsetse fly-borne disease of vertebrate animals, primarily of cattle and occasionally other animals. In humans, the parasites cause African trypanosomiasis or sleeping sickness. Our parasitology program includes a multidisciplinary study of the role of T cells and cytokines in the immunopathogenesis of trypanosome infections (Dr. Meiqing Shi), intravascular immune responses to T. brucei (Dr. Shi), dynamic interactions of immune cells with T. brucei in the brain (Dr. Shi). The intravital microscopy has been well used in Dr. Shi's laboratory to visualize interactions between immune cells and T. brucei.

We also study mucosal immune responses against gastrointestinal nematode parasites in livestock and animal models. In this nematode study, Dr. Zhu’s lab is collaborating with Dr. Wenbin Tuo through a research project agreement. Dr. Tuo is a senior research scientist at Animal Parasitic Diseases Laboratory, USDA ARS, Beltsville, MD.

Virology

The focus of several investigators at the Department is in the virology area, including Drs. George Belov, Weizhong Li, Siba Samal, Ekaterina Viktorova, Yanjin Zhang, and Xiaoping Zhu. Research topics of these investigators include the molecular mechanisms of viral infection, the role of host factors in the pathogenesis of hepatitis E virus (HEV), herpesvirus, influenza virus, paramyxovirus, picornavirus, and porcine respiratory and reproductive viruses (PRRSV), and the development of new vaccine candidates and anti-viral therapeutics.

Picornaviruses include important pathogens of humans and animals, such as foot and mouth disease, poliovirus, enterovirus D68, and many others — research by Drs. Belov and Viktorova focus on different aspects of virus-host interaction, mechanisms of viral replication, and the development of novel vaccines and anti-viral therapeutics. Dr. Samal joined the Department in 1988 after an outstanding training in Plum Island Animal Disease Center at the USDA. He is investigating molecular determinants and mechanisms of paramyxovirus virulence and pathogenesis. Using a reverse genetics system, his lab has engineered avian paramyxoviruses as vaccine vectors or oncolytic agents against animal and human diseases. Dr. Samal has received several US patents based on his innovative research. Dr. Zhang is investigating the pathogenesis and host response of the PRRSV and HEV. Dr. Zhang investigates the mechanisms of virus-cell interactions of HEV and PRRSV and has developed a novel PRRSV vaccine that allows the vaccine to induce interferon signaling in vivo. His vaccine has already received US patent. The research focuses of Drs. Zhu and Li are studying mechanisms of viral immune pathogenesis of respiratory syncytial virus (RSV) and are developing influenza and RSV mucosal vaccines. Their mucosal vaccination strategy has received US patents and licenses. Additionally, Dr. Zhu and Dr. Li study viral protein interferes with host innate and adaptive immune responses.