title: Selection of genetic variants of lymphocytic choriomeningitis virus in spleens of persistently infected mice. Role in suppression of cytotoxic T lymphocyte response and viral persistence.
abstract: We studied the mechanism of lymphocytic choriomeningitis virus (LCMV) persistence and the suppression of cytotoxic T lymphocyte (CTL) responses in BALB/c WEHI mice infected at birth with LCMV Armstrong strain. Using adoptive transfer experiments we found that spleen cells from persistently infected (carrier) mice actively suppressed the expected LCMV-specific CTL response of spleen cells from normal adult mice. The suppression was specific for the CTL response and LCMV -specific antibody responses were not affected. Associated with the specific CTL suppression was the establishment of persistent LCMV infection. The transfer of spleen or lymph node cells containing LCMV -specific CTL resulted in virus clearance and prevented establishment of the carrier state. The suppression of LCMV -specific CTL responses by carrier spleen cells is not mediated by a suppressor cell, but is due to the presence of genetic variants of LCMV in spleens of carrier mice. Such virus variants selectively suppress LCMV-specific CTL responses and cause persistent infections in immunocompetent mice. In striking contrast, wild-type LCMV Armstrong, from which these variants were generated, induces a potent CTL response in immunocompetent mice and the LCMV infection is rapidly cleared. Our results show that LCMV variants that emerge during infection in vivo play a crucial role in the suppression of virus-specific CTL responses and in the maintenance of virus persistence.
mesh_terms: D000208:Acute Disease; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D002353:Carrier State / Q000276:immunology* / Q000382:microbiology; D002472:Cell Transformation, Viral; D014644:Genetic Variation; D007108:Immune Tolerance; D007116:Immunization, Passive; D008216:Lymphocytic Choriomeningitis / Q000276:immunology* / Q000382:microbiology; D008217:Lymphocytic choriomeningitis virus / Q000235:genetics* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000166:cytology / Q000382:microbiology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000382:microbiology
chemical_list: D000914:Antibodies, Viral