Solid matrix-antibody-antigen complexes induce antigen-specific CD8+ cells that clear a persistent paramyxovirus infection.

We have previously shown that the adoptive transfer of splenocytes, isolated from mice immunized by infection with the paramyxovirus simian virus 5 (SV5), enhance the speed of clearance of SV5 from the lungs of immunodeficient mice; clearance is mediated primarily through CD8+ effector cells and not by serum neutralizing antibody (D.F. Young, R.E. Randall, J.A. Hoyle, and B.E. Souberbielle, J. Virol. 64:5403-5411, 1990). In this article we demonstrate that immunization of mice with solid matrix-antibody-antigen (SMAA) complexes also induces CD8+ effector cells that are responsible for clearing persistent SV5 infections in immunodeficient mice. The demonstration that immunization with SMAA complexes (an exogenous antigen) can induce class I-restricted cytotoxic T lymphocytes (CTLs) suggests that that these cells may be responsible for virus clearance in vivo. This premise is supported indirectly by the observation that immunization with SMAA complexes was less efficient in inducing class I-restricted CTLs (as measured in vitro) than was infectious virus and that splenocytes isolated from mice immunized with SMAA complexes were also less efficient in clearing virus from lungs of immunodeficient mice than were splenocytes isolated from mice immunized by infection with virus. This was not because the SMAA complexes were generally less immunogenic than infectious virus, since mice immunized with SMAA complexes (which contained the HN protein of SV5) produced higher levels of neutralizing antibody than mice immunized with infectious virus. In the majority of experiments, fixed and killed suspensions of Staphylococcus aureus Cowan strain A were used as the solid matrix in the construction of SMAA complexes. However, in this article we present evidence that alum-antibody-antigen complexes are as immunogenic as S. aureus A-antibody-antigen complexes. These results suggest that the immunological reactivity of the solid matrix itself does not influence the intensity of the immune response to the antigens of interest in the SMAA complexes. The significance of these results for vaccine design are discussed.