Effects of Sodium Valproate on the Replication of Herpes Simplex Virus Type 1: An in Vitro Study

Background: sodium valproate, an anticonvulsant drug, isreported to stimulate human immunodeficiency virus type iand human cytomegalovirus replication. since epileptic patientsundergoing sodium valproate therapy may suffer fromvarious virus infections, the effect of this drug on replicationof viruses especially those affecting neuronal tissues such asherpes simplex virus type i is worthy of investigation.methods: viral replication was studied by quantal responsemethod. electron microscopy was also performed on cellmonolayers treated with the drug and infected with the virus.results: significant reduction in viral infectivity was observedin cell cultures exposed to 0.5-2 mm of sodium valproateeither one hr before or after infection. the correspondingelectron microscopic examination revealed a very few intracytoplasmicenveloped virions and a marked reduction inthe number of intracytoplasmic nucleocapsids in drug-treatedvirus infected cells compared with those of infected control.however, significant stimulation of virus replication wasfound upon treatment of cells with i mm (p(less than)o.o i) and 2 mm(p(less than)o.oo i) of the drug 24 hours prior to infection. no remarkablechange was seen in corresponding electron micrographs.conclusion: although the ultimate outcome of this studyawaits in vivo assessments, possible stimulation of herpessimplex virus type i replication by sodium valproate shouldbe considered by clinicians prescribing this drug.