A Baculovirus Blocks Insect Molting by Producing Ecdysteroid UDP-Glucosyl Transferase

The predicted amino acid sequence of a newly identified gene of the insect baculovirus Autographa californica nuclear polyhedrosis virus was similar to several uridine 5′-diphosphate (UDP)-glucuronosyl transferases and at least one UDP-glucosyl transferase. Genetic and biochemical studies confirmed that this gene encodes an ecdysteroid UDP-glucosyl transferase (egt). This enzyme catalyzes the transfer of glucose from UDP-glucose to ecdysteroids, which are insect molting hormones. Expression of the egt gene allowed the virus to interfere with normal insect development so that molting was blocked in infected larvae of fall armyworm ( Spodoptera frugiperda ).