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Replication of herpes simplex virus in blood monocytes and placental macrophages from human neonates
S Plaeger-Marshall1, B J Ank, K M Altenburger
1Department of Pediatrics, UCLA School of Medicine 90024-1747.
Abstract:
Increased permissiveness of macrophages for herpes simplex virus (HSV) replication may be a mechanism for the dissemination and severity of neonatal herpetic infection. We have assessed the replication of HSV in neonatal blood monocytes and placental macrophages using several criteria for viral permissiveness. Assay of production of infectious progeny virus indicated that cord blood monocytes, like adult monocytes, were nonpermissive for HSV (about 1% of cells producing virus). In vitro culture of cord blood monocytes resulted in increased replication of HSV, but no greater extent than virus production in cultured adult cells. HSV infection of fetal placental macrophages was weak but present (4.4% of cells). Assay of production of viral antigens and electron microscopic analysis of structural elements indicated that a larger number of cord blood monocytes and placental macrophages were abortively infected than were productively infected. These results indicate that monocytes and macrophages from human neonates do not show the enhanced permissiveness for HSV demonstrated in newborn mice and suggest that dissemination of herpetic infection in human newborns cannot be explained by increased neonatal monocyte permissiveness for HSV.
Insights
Neonatal monocytes and placental macrophages are not more permissive to herpes simplex virus (HSV) replication than adult cells. This suggests increased permissiveness in neonatal immune cells does not explain severe herpetic infections in newborns.
Area of Science:
- Immunology
- Virology
- Neonatal Medicine
Background:
- Neonatal herpetic infections can be severe, with dissemination potentially linked to increased viral permissiveness in immune cells.
- Macrophages and monocytes play crucial roles in immune responses and viral infections.
Purpose of the Study:
- To investigate whether neonatal monocytes and placental macrophages exhibit enhanced permissiveness to herpes simplex virus (HSV) replication compared to adult cells.
- To determine if increased HSV replication in neonatal immune cells contributes to the severity of neonatal herpetic infections.
Main Methods:
- Assessed HSV replication in human neonatal cord blood monocytes and placental macrophages.
- Utilized assays for infectious progeny virus production, viral antigen production, and electron microscopy.
- Compared HSV replication in neonatal cells with that in adult monocytes and in vitro cultured cells.
Main Results:
- Cord blood monocytes showed low permissiveness to HSV, similar to adult monocytes (approx. 1% productive infection).
- In vitro culture of neonatal monocytes increased HSV replication but not beyond levels seen in cultured adult cells.
- Fetal placental macrophages showed weak HSV infection (4.4% of cells), with a higher proportion of abortive infections.
- Neonatal monocytes and placental macrophages did not demonstrate enhanced permissiveness for HSV compared to adult cells.
Conclusions:
- Human neonatal monocytes and macrophages are not significantly more permissive to HSV replication than adult counterparts.
- The enhanced permissiveness observed in newborn mice for HSV is not replicated in human neonatal immune cells.
- Increased permissiveness of neonatal monocytes and macrophages does not explain the dissemination and severity of herpetic infections in human newborns.