GENE-TRANSFER INTO SYMPATHETIC PREGANGLIONIC NEURONS IN-VIVO USING A NONREPLICATING THYMIDINE KINASE-DEFICIENT HERPES-SIMPLEX VIRUS TYPE-1

The suitability of non-replicating thymidine kinase deficient herpes s implex virus type 1 expressing bacterial beta-galactosidase (tk(-)lacZ HSV-1) as a transfer vehicle into sympathetic preganglionic neurons i n vivo was assessed. Many sympathoadrenal preganglionic neurons (451+/ -105) with normal morphology were identified using beta-galactosidase histochemistry two days after inoculation of tk(-)lacZ HSV-1 into the adrenal gland of hamsters. beta-Galactosidase activity co-localized wi th nicotinamide adenine dinucleotide phosphate-diaphorase-positive sym pathetic preganglionic neurons in the nucleus intermediolateralus, par s principalis. The maximal number of beta-galactosidase expressing neu rons was found two days post-inoculation but this number dropped drama tically after this time. An inflammatory infiltrate was abundant aroun d infected neurons and in the white matter at five days and infected n eurons appeared morphologically abnormal. At 26 days, the infiltrate w as still present but no infected sympathoadrenal preganglionic neurons were detected. Approximately 25% fewer nicotinamide adenine dinucleot ide phosphate-diaphorase-positive neurons in the nucleus intermediolat eralis, pars principalis were counted ipsilaterally than contralateral ly in animals infected For 14, 21 or 26 days with tk(-)lacZ HSV-1, com pared to the 3% difference in animals mock-infected for 26 days. Appro ximately 33% of the estimated number of sympathoadrenal preganglionic neurons infected with tk(-)lacZ HSV-1 at five days were apoptotic or n ecrotic. About 60% of neurons infected with tk(-)lacZ HSV-1 al two day s no longer expressed nicotinamide adenine dinucleotide phosphate-diap horase at 14-26 days. In conclusion, the non-replicating thymidine kin ase deficient HSV-1 was efficiently retrogradely transported from the adrenal gland to infect sympathoadrenal preganglionic neurons. These g ene transfer experiments using tk(-)lacZ HSV-1 suggest that foreign ge ne expression in sympathetic preganglionic neurons in vivo may be maxi mal two days after inoculation when beta-galactosidase was expressed i n the greatest number of sympathetic preganglionic neurons. After two days, fewer neurons expressed beta-galactosidase and the presence of t k(-)lacZ HSV-1 appeared to be altering protein expression in sympathet ic preganglionic neurons and/or leading to the demise of the infected neuron. (C) 1997 IBRO. Published by Elsevier Science Ltd.