Duke University’s Singapore medical school agreed to work with closely held Inviragen Inc. to develop a vaccine against dengue fever, joining Sanofi Aventis SA in the quest for a shot against the deadly virus.

The Duke-National University of Singapore Graduate Medical School signed a memorandum of understanding with Fort Collins, Colorado-based Inviragen to “better understand how emerging infectious diseases are transmitted and how transmission can be prevented,” the two organizations said in a statement today.

Duke-NUS and Inviragen plan to start trials of experimental vaccines against dengue and hand, foot and mouth disease in Singapore, they said, without saying when the studies will begin. Paris-based Sanofi started the third and final stage of trials of its dengue vaccine last year.