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 plantsanimals, 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.