Effect of dexamethasone on herpes simplex virus replication in mouse neuroblastoma cells (NB41A3): receptor...

Monolayers of NB41A3 (MNB) cells were exposed to pharmacologic doses of dexamethasone (DXM). After 24-h, the cells were infected with herpes simplex virus type 1 (HSV-1) at a multiplicity of infection (m.o.i.) = 0.1. After every 24-h period, extracellular and intracellular virus aliquots were collected and frozen. The aliquots were titered in a standard plaque-forming assay. It was shown that the hormone led to a statistically significant increase of extra- and intracellular virus titers above the titers exhibited by these cells without added hormone. The same experiment was repeated in Vero cells, but the hormone did not elevate the resultant HSV-1 titers. A binding assay was performed on these two cell lines by use of 3H-DXM to determine if a DXM receptor was present. Specific binding was seen, but only in the MNB cell line. The Bmax of this receptor was 480 fmol/mg protein and it had a Kd of 2.3 nM. The S value of the receptor ligand complex equalled 8.0. These results indicate that cells possessing hormone receptors allow for a more efficient replication of the virus and suggest that these hormones may play an important role in the exacerbation of herpes simplex virus infection in vivo.