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Lipopolysaccharide inhibits the production of lymphocytic choriomeningitis virus in a human monocytic cell line
Abstract
The human monocytic cell line THP-1 was used as a model to study the mechanism of infection in the monocyte/macrophage, a natural target of lymphocytic choriomeningitis virus (LCMV) infection in vivo. Both the virulent strain, LCMV. WE, and the avirulent strain, LCMV. ARM, infected THP-1 cells, but did not stimulate THP-1 cells to secrete interleukin 1 (IL-1) or tumour necrosis factor (TNF-α). When lipopolysaccharide (LPS) was added to THP-1 cells together with LCMV, an 80 to 90% reduction in the number of infected cells (measured by immunofluorescence) and a 90% reduction in viral plaques was observed 5 to 6 days postinfection. Neither interferon α (IFN-α) nor IFN-β were detected in supernatants from THP-1 cells after the addition of LCMV, LPS, or LPS plus LCMV. In contrast, the same levels of IL-1 and TNF-α were observed in the presence of LPS and LCMV, or LPS alone. However, antibodies to IL-1, TNF-α, interleukin 6 and IFN-α did not block the antiviral effect of LPS. In kinetic studies, LPS added 1 day after adding LCMV to THP-1 cells was still effective in reducing the number of infected cells. Our findings suggest that LPS alters cellular metabolism, possibly through the induction of IFN-α, and that IFN-α in the absence of LPS suppresses virus production.
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© Society for General Microbiology 1993