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Replication of HSV-1 in murine peritoneal macrophages: comparison of various virus strains with different properties
Abstract:
The in vitro replication of eleven different strains of herpes simplex virus type 1 was studied in resident or thioglycollate-stimulated mouse macrophages. The strains of herpes simplex virus differed in the type of cytopathic effect, induction capacity for herpes simplex virus coded thymidine kinase and pathogenicity in the mouse. Herpes simplex virus replicated better in thioglycollate-stimulated macrophages than in resident macrophages. In vitro ageing of macrophages increased their replicative potency. Herpes simplex virus replicated better in macrophages from homozygous bg/bg C57/BL6J mice than in macrophages from their heterozygous littermates. Separation of macrophages on discontinuous Percoll-gradients revealed 4 fractions with identical potency for replication. The ability of herpesvirus to replicate in macrophages varied from strain to strain of virus i.e. Wal greater than Len, clone 4 of Len, greater than L3-2s, JES, Ang-, Ang + path, clone 2 of Len and greater than MDK clones. The ability to cause cytopathology also varied. Only strains Ang- and Ang + path showed limited or late cytopathology in macrophages. The cell-fusing property of herpes simplex virus appeared to be more closely correlated with lower replication rates than production cell rounding. Thymidine kinase- viruses replicated less well than thymidine kinase+ or thymidine kinase(+) strains. Strains of herpes simplex virus with high or low pathogenicity for mice replicated in macrophages to the same degree. The phagocytic activity of macrophages for IgM-coated sheep red blood cells was inhibited earlier by strains of herpes simplex virus of type 2 than by strains of herpes simplex virus of type 1.
Insights
Herpes simplex virus type 1 replicates better in stimulated or aged mouse macrophages, with variations observed among different viral strains. Macrophage replication capacity was not influenced by mouse genetics or Percoll gradient fractions.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Macrophages play a crucial role in antiviral defense.
- Herpes simplex virus (HSV) is a common human pathogen with diverse strains.
- Understanding HSV-macrophage interactions is key to controlling viral infections.
Purpose of the Study:
- To investigate the in vitro replication of different herpes simplex virus type 1 (HSV-1) strains in mouse macrophages.
- To determine factors influencing HSV-1 replication in macrophages, including macrophage activation, age, and genetic background.
- To correlate viral characteristics like cytopathic effect, thymidine kinase activity, and pathogenicity with replication efficiency in macrophages.
Main Methods:
- In vitro replication assays of eleven HSV-1 strains in resident and thioglycollate-stimulated mouse macrophages.
- Macrophage aging protocols and genetic variations (homozygous bg/bg vs. heterozygous C57/BL6J mice) were employed.
- Percoll gradient centrifugation was used to separate macrophage populations.
- Viral replication, cytopathic effect, cell fusion, and thymidine kinase activity were assessed.
- Phagocytic activity of macrophages was measured.
Main Results:
- HSV-1 replicated more efficiently in thioglycollate-stimulated and in vitro-aged macrophages.
- Macrophages from homozygous bg/bg mice supported better HSV-1 replication than those from heterozygous littermates.
- Significant variation in replication rates and cytopathic effects was observed among different HSV-1 strains.
- Viral thymidine kinase (TK) activity correlated positively with replication efficiency; TK- viruses replicated less well.
- Viral pathogenicity in mice did not correlate with in vitro macrophage replication rates.
- HSV-2 strains inhibited macrophage phagocytic activity earlier than HSV-1 strains.
Conclusions:
- Macrophage activation, aging, and specific viral strain properties significantly influence HSV-1 replication.
- HSV-1 replication in macrophages is strain-dependent and influenced by factors such as TK activity.
- While mouse genetics and macrophage fractions did not show differential replication, HSV-2 exhibited a stronger impact on macrophage phagocytosis.