In vitro reactivation of latent herpes simplex virus by the demethylating compound hexamethylene-bis-acetamide

We have characterized previously a model of herpes simplex virus (HSV) infection of rat dorsal root ganglia (DRG) following cutaneous infection. During acute infection HSV can be isolated from co-cultivated rat ganglia in (mean +/- S.E.M.) 4.8 +/- 0.33 days (d) and from latently infected ganglia in 7.8 +/- 0.53 (d) (P < or = 0.0001). We treated co-cultivated rat ganglia from acute and latent infected rats with the demethylating compound hexamethylene-bis-acetamide (HEX) to see what effect, if any, it would have on HSV infection. HEX-treated ganglia from rats with acute infection did not differ significantly from controls in the proportion of rats, skin or ganglia positive for HSV. The mean time to detect virus was not different between treated (3.6 +/- 0.38 d) and control (3.1 +/- 0.46 d) (P > 0.05) groups. In latent infected rats there was no difference between treated and controlled groups in the proportions of rats, skin and ganglia positive for HSV. There was a significant difference in the mean time to CPE between the HEX and control groups respectively (4.5 +/- 0.72 d vs 8.92 +/- 1.42 d, P < 0.01). We conclude that HEX converted latent HSV infection to a productive one.