Localization of juvenile hormone esterase during development in normal and in recombinant baculovirus-infected larvae of the moth Trichoplusia ni.

The pathogenesis and cellular localization of juvenile hormone esterase (JHE) was examined in larvae of the moth Trichoplusia ni, infected with a recombinant baculovirus (Autographa californica nuclear polyhedrosis virus: AcNPV) engineered to produce high levels of JHE (JHE virus). The course of JHE localization in the recombinant virus infected larvae was compared with that of both wild type AcNPV infected, and uninfected larvae, using immunogold electron microscopy. In the JHE virus infected insects, high levels of JHE were observed in the endoplasmic reticulum of all cells showing evidence of viral structures in the nucleus, except for gut cells which showed only background JHE levels. Tracheole cells and haemocytes appeared to play a role in the dissemination of infection. In uninfected larvae, fat body and epidermis were the major tissues staining for JHE, which was only detectable at peak times of JHE activity during the fifth instar: lower levels at other times could not be distinguished from background. JHE was also present in lysosomes of granular haemocytes: these lysosomes increased in number in the fifth instar compared to the fourth instar. Similar lysosome-like granules in the pericardial cells did not become highly positive for JHE antigen until the fifth instar.