Fig. 1. Photomicrographs of cultured mouse dorsal root ganglion (DRG) neurons. ( A ) Nomarski (1,000×) photo of DRG cells without calcitonin gene–related peptide (CGRP) primary antisera. ( B ) Strong CGRP immunoreactivity in a DRG neuron treated with capsaicin but not with virus (630×). ( C ) Strong CGRP immunoreactivity in DRG neurons treated with both capsaicin and control virus (KHZ) (630×). ( D, bottom ) Mild CGRP immunoreactivity in a DRG neuron treated with capsaicin and KACGRP (630×). ( D, top ) Diagram of recombinant herpes vector KACGRP. An antisense sequence to the gene for rat CGRP (A-CGRP) is inserted, under the control of a human cytomegaloviral immediate/early promoter/enhancer (hCMV IEP) sequence into the thymidine kinase (TK) sequence of the genome of an attenuated herpes simplex type 1 virus. Insertion into the TK sequence disables this gene and thus prevents replication in nondividing cells. A similar virus, KHZ, was constructed encoding for the bacterial reporter gene lac-Z and was used as a control. KACGRP = antisense CGRP viral vector; SV40 PA = simian virus 40 polyadenylation sequence; UL= unique long sequence, US= unique short sequence.