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Immunosuppression by Moloney leukemia virus: lack of correlation between virus replication and the immunosuppressive
Abstract:
Young adult mice were infected with 10(4) plaque-forming units (PFU) or Moloney murine leukemia virus M-MuLV. Two different virus preparations were used: a) M-MuLV obtained from serial passage in mice [animal passage (AP)] and b) tissue culture (TC)-grown virus harvested after three in vitro passages of the AP M-MuLV in fibroblasts. Replication of TC and AP M-MuLV in spleen cells was determined by an infectious center (IC) assay at 1 and 2 weeks after the infection. Immune responsiveness of spleen cells was evaluated in challenge with sheep red blood cells (SRBC) and subsequent enumeration of antibody plaque-forming cells (PFC). TC M-MuLV replicated faster in the spleen than did AP M-MuLV and reached about 10- to 100-fold higher titers. However, the response of anti-SRBC PFC, suppressed to the same degree in the spleens of mice infected with TC or AP virus, was from 10 to 50% of the control response. A comparison of virus replication with the anti-SRBC response in aliquots from the same spleens showed no correlation between virus IC and antibody PFC. Both TC and AP M-MuLV induced the expression of virus-specific, cell membrane antigen on spleen cells. These findings indicated a divergence between virus replication on the one hand and the immunosuppressive effect and the cell membrane alteration on the other.
Insights
Moloney murine leukemia virus (M-MuLV) replication in mice spleen cells differed based on preparation. Despite faster replication of tissue culture-grown M-MuLV, both preparations equally suppressed immune response and altered cell membranes.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Moloney murine leukemia virus (M-MuLV) is a retrovirus known to infect mice.
- Different virus preparation methods, such as animal passage (AP) and tissue culture (TC) passage, can influence viral properties.
- Understanding M-MuLV's replication and its effects on the immune system is crucial for retroviral research.
Purpose of the Study:
- To compare the replication kinetics of AP M-MuLV and TC M-MuLV in mouse spleen cells.
- To evaluate the impact of both M-MuLV preparations on spleen cell immune responsiveness.
- To investigate the relationship between M-MuLV replication, immunosuppression, and cell membrane antigen expression.
Main Methods:
- Young adult mice were infected with either AP M-MuLV or TC M-MuLV.
- Viral replication in spleen cells was quantified using an infectious center (IC) assay.
- Immune response was assessed by enumerating antibody plaque-forming cells (PFC) against sheep red blood cells (SRBC).
Main Results:
- TC M-MuLV demonstrated significantly faster replication and higher titers in spleen cells compared to AP M-MuLV.
- Both AP and TC M-MuLV suppressed the anti-SRBC PFC response to a similar extent, indicating no correlation with viral replication levels.
- Virus-specific cell membrane antigen expression was induced by both M-MuLV preparations on spleen cells.
Conclusions:
- Viral replication rate in spleen cells diverges from the immunosuppressive effects and cell membrane alterations induced by M-MuLV.
- The preparation method of M-MuLV influences its replication kinetics but not its capacity to suppress immune function or alter cell surface antigens.
- These findings highlight distinct mechanisms underlying M-MuLV's replication and its immunomodulatory properties.