Shyi-Dong Yeh was born and raised in Taiwan, Republic of China, and earned his B.Sc. (1974) and M.S. (1979) degrees in plant pathology from National Chung Hsing University. He matriculated to Cornell University and received his Ph.D. degree in plant pathology in 1983. Yeh then joined the Plant Pathology Department of the National Chung Hsing University in 1984 and was promoted in 2006 to chair professor of plant pathology, one of only nine chair professors of the university. In 2004, Yeh was appointed as the vice president of National Chung Hsing University. Yeh’s extraordinary contributions to fundamental and practical virological research are documented in his more than 90 publications.
Yeh’s research has always targeted economically important viruses with the aim of developing effective control measures. This philosophy is shown by his works on Papaya ringspot virus (PRSV), Zucchini yellow mosaic virus (ZYMV), and tospoviruses. During his Ph.D. research, Yeh developed a mild nitrous acid mutant of PRSV and he subsequently led the effort to deploy the mild PRSV in large-scale cross-protection of papaya in Taiwan. Yeh was the first to show that PRSV RNA is translated into a polyprotein that is subsequently cleaved into functional protein products, the first to sequence the PRSV genome, and the first to develop infectious transcripts of the virus. He then proceeded to reveal the viral determinants for symptom attenuation, viral movement, local lesion expression, host range, and viral-induced suppression of gene silencing. He showed that symptom attenuation of PRSV was due to mutations in the P1 and HC-Pro genes and that the differences in host range of the cucurbit-infecting PRSV-W and the cucurbit- and papaya-infecting PRSV-P types are due to mutations in the NIa and NIb regions of the genome. Using this knowledge, Yeh has “custom-made” mild strains of PRSV that are highly effective in cross-protecting against PRSV in cucurbits.
Yeh’s ability to use a variety of technologies and fundamental knowledge toward a practical end is again illustrated by his development of PRSV-resistant transgenic papaya. His laboratory developed transgenic papaya that showed excellent resistance to a range of PRSV isolates from different countries and performed well in field trials. The transgenic papaya is now going through the process of deregulation in Taiwan and could be the first transgenic papaya to be deregulated outside the United States. Following the observation that a specific naturally occurring strain of PRSV overcame the transgenic resistance, Yeh constructed a recombinant PRSV to show that the HC-Pro gene of the naturally occurring PRSV suppressed the gene silencing in the transgenic papaya to overcome its resistance. His lab recently developed a new transgenic papaya with resistance to PRSV and Papaya leaf distortion mosaic virus, which he had recently discovered in Taiwan.
In the late 1990s, Yeh began to develop mild strains of ZYMV for controlling ZYMV by cross-protection. Infectious transcripts of ZYMV were developed and used to develop fundamental knowledge on the sequence determinants that govern symptom expression, viral movement, and host range. This information was then used to create mild recombinant strains of ZYMV, which conferred effective cross-protection against ZYMV in cucurbits.
Yeh has greatly advanced the field of tospoviruses, especially in Asia. Early on, people assumed that Tomato spotted wilt virus was the main tospovirus in Taiwan. Instead, Yeh identified three new tospoviruses as the prevalent ones in Taiwan. He then proceeded to serologically and molecularly characterize these viruses. Yeh produced polyclonal and monoclonal antibodies against the nucleocapsid proteins of the five major serogroups of tospoviruses and also produced a monoclonal antibody that is effective in detecting most Asian tospovirus species. These antibodies are now widely used for detecting and characterizing tospoviruses. Furthermore, Yeh identified and demonstrated that degenerate primers designed from the conserved regions of the L genes of tospoviruses can be used as a genus-specific tool for detection of tospoviruses by RT-PCR. His lab has led the effort to organize all reported tospoviruses by proposing a new classification scheme of the 16 current species based on their phylogenetic and serological relationships.
Yeh has also pioneered the use of potyviruses as vectors for producing useful proteins in plants. His lab constructed a modified ZYMV as a vector to express tospovirus proteins and a mite allergen (Der p 5) in cucurbits. The isolated mite allergen was subsequently tested in mice and shown to down regulate allergen-induced airway inflammation and immunoglobulin E synthesis when administered orally. Most recently, Yeh has characterized the effectiveness and stability of heterologous protein expression in plants by using Turnip mosaic virus. This research has established the optimal conditions for the use of potyvirus vectors for expressing a range of proteins in plants, including those with pharmaceutical value.
The ever-expanding quest of Yeh’s laboratory for developing effective means to control plant viruses can be seen in his collaborative work with Nam-Hai Chua of Rockefeller University. They recently showed that small transgenes consisting of artificial micro RNAs confer resistance to plant viruses. This approach has the promise to be simple and effective for designing transgenes to confer virus resistance.
The contributions of Yeh to his country go far beyond research. He established the modern virology program at National Chung Hsing University and has been the major professor for 40 M.S. and 10 Ph.D. students. He served as the director of the Biotechnology Center for National Chung Hsing University and chaired the Plant Biotechnology Resources Center for promoting biotechnology education for the five national universities of Taiwan. Under his guidance as vice president of National Chung Hsing University for scientific affairs, the government awarded the university a 5-year funding of 13 million U.S. dollars annually to promote National Chung Hsing University as one of the top universities in Asia in agricultural biotechnology. The international and national recognition of Yeh is evidenced by his more than 40 invitations to speak at international scientific conferences and numerous outstanding research awards.