Cytotoxic T cells induced by infection with virus A will kill target cells
The CD8+ cytotoxic T cells have antigen specific T-cell receptors (TCR) on their membranes that will recognize and bind to self class I antigens. Since the viral peptides are presented as a complex with the self class I antigens, the CD8+ cells can now recognize and react to the virus A peptides. Remember that class I antigens are expressed on all nucleated cells and platelets. Ref: Levinson W. (2012). Chapter 58. Cellular Basis of the Immune Response. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.
From the same host infected with any virus
Infected by virus A and identical at class I MHC loci to the cytotoxic T cells
Infected by virus A and identical at class II MHC loci to the cytotoxic T cells
Infected with any virus and identical at class I MHC loci to the cytotoxic cells