Differential recruitment of viral and allo-epitopes into the MHC class I antigen processing pathway of a novel mutant of Ltk- cells. HSV/MHC class I restriction/immune recognition/antigen processing/antigen presentation/influenza virus.

Abstract

It is generally thought that the Ag processing pathways for endogenously synthesized proteins are the same for allo and viral Ag processing. However, this view does not take into consideration the diversity of specialized maturation and assembly pathways for viruses. In particular, viral assembly that takes place within intracellular membranes may require unique Ag processing steps. In this study we sought to assess this possibility. Hence, we describe the CTL response against a murine Ltk- cell derivative, gro29, which was previously shown to be defective in the propagation of herpes simplex virus type 1 (HSV-1). In HSV-1-infected gro29 cells, viral polypeptides are synthesized in normal amounts and viral assembly takes place. However, transport of the assembled particles is defective in these cells, resulting in the accumulation of noninfectious virus in cytoplasmic vesicles, and a reduction in the release of viral particles by at least 2000-fold. We show that the rate of transport of individual endogenous proteins through the organelles of the secretory pathway is also impaired, but only by roughly 50%, suggesting that the defect in this cell line affects the transport of particles to a greater extent than the transport of individual proteins. It is also shown that allogeneic and influenza A- specific CTL responses are indistinguishable between gro29 and Ltk- cells, as is the response against target cells pretreated with a influenza A derived synthetic peptide. By contrast, HSV-1-infected gro29 cells are approximately eightfold less sensitive than infected Ltk- cells to lysis by HSV-1-specific CTL. This illustrates that in contrast to the allogeneic and influenza specific responses, the recruitment of herpes virus-specific Ag into the Ag-processing pathway is dependent on a cellular function that is also required for viral maturation and egress. We believe that this is the first demonstration of this phenomenon.