THE EFFECT OF GESTATIONAL AGE AND LABOR UPON INTRACELLULAR SURVIVAL OF HERPES SIMPLEX VIRUS (HSV)

Neonatal HSV infection is often characterized by rapid, life-threatening dissemination. Perinatal immunologic factors examined to date incompletely account for this tendency to disseminate, for the rapid disappearance of this vulnerability early in postnatal life, and for the disproportionate occurrence in prematures. To determine a possible influence of gestational age or perinatal events upon this phenomenon, we studied 29 placental specimens of varying gestational age and mode of delivery. The intracellular survival of type 2 HSV within placental lymphocytes was assessed at 48 hour intervals for 6 days to determine the frequency and magnitude of virus titer changes. Early (0-48hrs) titer increases were significantly (p=0.015) more frequent in specimens with gestational age ≤ 35 wks (3/8) than those with ≥ 36 wks (0/21) gestations. Titer increases from 48 to 96 hours were common (14/29) but bore no relationship to gestational age, labor, or mode of delivery. Most importantly, late (>96 hrs) titer increases were most influenced by the occurrence of labor and unrelated to gestational age. Late titer increases did not occur in specimens from caesarian section without labor(0/12) and were significantly (p=0.023) more frequent in specimens where labor occurred (7/17). These findings are consistent with the hypothesis that early gestational age and the occurrence of labor transiently provide a more permissive intracellular environment for HSV replication and dissemination.