ADENOVIRUS-MEDIATED GENE-TRANSFER IN OLFACTORY NEURONS IN-VIVO

We used recombinant adenoviruses as a means of expressing exogenous ge nes in olfactory neurons in vivo. A replication incompetent adenovirus (type 5, Ad5) carrying the reporter gene lacZ, which codes for the en zyme beta-galactosidase (beta-Gal), was applied in solution to the olf actory epithelia of rats. The expression of lacZ was controlled by the cytomegalovirus immediate-early promoter/enhancer. beta-Gal expressio n was observed 1 day postinfection and was maximal at 3-10 days, altho ugh it could be detected fbr at least 21 days postinfection, Expressio n patterns were heterogeneous, ranging from a few percent to over 25% of the cells in different regions of both turbinate and septal epithel ium, Staining was stronger in the olfactory versus respiratory epithel ia. In olfactory epithelium staining uas almost entirely restricted to olfactory neurons. beta-Gal staining was also observed in the olfacto ry axons so that were bundles could be traced to their targets in the glomerular layer of the olfactory bulb. Intense staining of some glome ruli was evident as long as 21 days postinfection. There was no eviden ce of cell loss or tissue damage due to viral infection, These results demonstrate that it is possible to use recombinant Ad5 for expressing foreign genes in olfactory neurons. This technique could be used in o lfactory neurons to increase expression levels of olfactory specific g enes, including the odor receptor, putative guidance and growth molecu les, or elements of the transduction cascade, in order to elucidate th eir biological functions in vivo. (C) 1996 John Wiley & Sons, Inc.