Immunohistological characterisation of acute herpes simplex virus infection of lumbar dorsal root ganglia in the rat.

After inoculation of herpes simplex virus (HSV) into the dorsal skin of the hind paw of rats, HSV antigen was detected in dorsal root ganglion neurones by immunohistochemistry. Antigen was first detected 2 days after inoculation. Between 2 and 4 days after inoculation, numerous small-type unmyelinated neurones gave positive staining reactions for HSV antigens. Necrosis of neuronal cells was evident by 4 days. Antigen was not detected 6 or 9 days after inoculation. Immunohistological studies of co-cultivated ganglia removed from the infected monolayers, immediately after cytopathic effect first appeared or 24 h later, uniformly revealed virus antigen staining of small-type unmyelinated neuronal cells.