The Responses of Normal and Athymic Mice to Infections by Togaviruses: Strain Differentiation in Active and Adoptive Immunization

Abstract

Strains of yellow fever virus (YFV), Venezuelan equine encephalomyelitis virus (VEEV) and Semliki Forest virus (SFV) were used to compare the stimulations of regulatory immunity (pre-challenge), antibody synthesis and protective immunity (post-challenge) in athymic-nude and normal mice. Direct assessments were extended to athymic recipients of normal spleen cells and to adoptively immunized mice. The responses of mice to different togaviruses or strains of togaviruses may be differentially T [thymus-derived]-lymphocyte-dependent at any of the above 3 stages of host response. T cell reconstitution or adoptive immunization may be effective only for the virus strains of highest immunogenicity. These results suggest a resolution of T lymphocyte dependence at 3 levels of host response to virus infections. This approach may be of value in the similarly direct in vivo differentiation of other virus strains and as a practical framework for the consideration of the in vivo significance of the variety of in vitro lymphocyte markers.