I've seen a question answered by telling me that viral peptide can be loaded on MHC II on APC! how is that possible?
I understand that viral peptides should be presented by class I (the endogenous pathway).
If the Antigen Presenting Cell has engulfed a cell that was previously infected with a virus, then yes it will present the viral peptides onto its MHC II molecule. But remember this peptide will not be recognized by CD8 but rather by CD4. The T helper will then decide what to do, like going in the TH1 or TH2 arms of the immune cascade.