Peritoneal macrophage barrier to the spread of semliki forest virus in mice

Author

Carina E. Elfström Walder

Date of Award

6-1987

Degree Type

Thesis

Degree Name

Master of Science

Major

Microbiology

Major Professor

Carl J. Wust

Committee Members

Arthur Brown, Robert N. Moore

Abstract

The intraperitoneal route for infection of mice with SFV was several thousand fold less efficient than the footpad, intravenous or intracerebral routes. Peritoneal resistance could be demonstrated in three strains of mice (C₃H/Ten, ICR, and C₃H/Hen), and increased with increasing age. Anti-viral factor(s) could not be found in the peritoneal washings of normal mice, as determined by pretreatment of the virus or L929 cells, or by inclusion of the washings in growth medium or agar overlays of infected cells throughout infection. In addition, anti-viral factor(s) were not produced by normal peritoneal cells in vitro. Very low amounts of IFN α/β could be detected in the peritoneal cavity of normal mice, which apparently increased slightly after viral infection. To determine the importance of the IFN for disease outcome in infected mice, anti-IFN α/β was administered intraperitoneally before SFV challenge. This treatment marginally reduced the mortality of the mice, and apparently played little role in the peritoneal resistance to SFV infection.

We next concentrated on the macrophages. LPS, which activates macrophages and induces IFN production (8), reduced the mortality of mice to SFV challenge (about 40%) whereas thioglycollate did not. Silica-treatment to destroy had little, if any effect on the survival of mice to SFV infection, and peritoneal washings performed immediately before viral challenge did not remove the peritoneal barrier. Protein A, which stimulates lymphocyte proliferation (70), also had little or no effect on extent of mortality.

A very low percentage (<2%) of peritoneal macrophages could, by immunofluorescence, be shown to contain viral antigens after in vivo and in vitro infection with SFV. The antigens were, however, only seen on or below the plasma membrane as a thin rind. The fraction of cells containing viral antigens could not be increased by increasing the multiplicity of infection. The presence of viral antigens did not increase per cell or in the number of cells beyond what was seen immediately after exposure to virus, even after four days in culture. Furthermore, the macrophages that were initially resistant to the uptake of SFV remained so throughout the period of time tested (4 days). Both UV-inactivated and live virus appear to be taken up equally well by a small number of macrophages. Live virus could be detected by plaque assays of the culture supernanant fluids from "infected" macrophages, even though in very low titers, which decreased during the time of infection through three days. On the fourth day after infection, however, an increased titer of live virus, even though still low, (from 0.001/cell to 0.1/cell) could be detected. In addition, on the fourth day viral antigens were no longer detected in the macrophages by immunofluorescence. Furthermore, cytopathic effects were never seen in cultures of macrophages exposed to SFV.

In contrast to the well-known accepted systemic hematogenous route of spread to the CNS from the natural (blood vessel) and various experimental routes of inoculation, SFV was found to traverse the sciatic nerve from the site of footpad infection.

Recommended Citation

Walder, Carina E. Elfström, "Peritoneal macrophage barrier to the spread of semliki forest virus in mice. " Master's Thesis, University of Tennessee, 1987.
https://trace.tennessee.edu/utk_gradthes/13612