Inapparent Herpes Simplex Virus Infection in Inoculated Rabbits

Summary

Rabbits were inoculated in the oral mucosa adjacent to submaxillary gland ducts with 10^5.7 plaque-forming units of herpes simplex virus (HSV). Gross ulcerations involving the ductal orifices appeared within 4 days and re-epithelialized within 7 days. Histological signs of HSV infection were present in ductal specimens examined on the 8th day but not in specimens examined at subsequent times. HSV was detectable in the saliva of 10 of 13 rabbits for varying periods of time after the surface lesions had healed. Though the virus was most readily isolated during the first 3 to 4 weeks following inoculation, it was not always recovered from a given animal on consecutive attempts. HSV was isolated from the saliva of one animal 169 days after inoculation. In addition, the virus was isolated from the saliva of 2 rabbits 747 and 996 days, respectively, after they had been inoculated intraperitoneally. HSV neutralizing antibody was not manifest in pre-inoculation sera or in sera taken within 5 days after infection. Within 9 days antibody was present in low titer and reached peak levels in most of the rabbits within 2 to 4 weeks. Repeated antibody assays performed at various times over a period of 3 to 21 months revealed that relatively low levels of antibody persisted in the animals tested. The titer of several rabbits, however, appeared to fluctuate during this time.

The authors gratefully acknowledge the excellent technical assistance of Mr. C. T. Mitchell and Mr. G. M. Lewis.