Answer:
(1)Cytokins are signalling molecules which are freed by the  infected viral cells that  brings about the nearby cells to increase their antiviral defences.
(2)Since  viruses are intra-cellular pathogens, the antigen noticed there is by the process of the endogenous pathway, n this pathway the virus proteins are reduced into fragment peptide and there present with  MHC classl molecules to the CD8 T cells.
(3) Once virus enters into a cell, it takes on the host replicative machinery to producing  its proteins. Some of theses viral proteins are degraded into peptide fragments which are present along with class1 MHC molecules which therefore are recognized by the CD8 T cells.
Explanation:
Solution
(1)  The production of interferons refers to  a process in which a cell uses a cytokine to reduce the production of viral in a tissue which is a part of a group large of proteins called cytokines,
Cytokins are signalling molecules which are freed by the  infected viral cells that  brings about the nearby cells to increase their antiviral defences. They are called so because of their ability to intervene with viral proliferation.
(2)Because viruses are intracellular pathogens, the antigen present is  by means of the endogenous pathway.
In this pathway the virus proteins are reduced into fragment peptide and there along with  MHC classl molecules to the CD8 T cells.
However, Bacteria  are centralized by the cells into endocytic vesicles which combine  with the lysosomes causes antigenic peptides. These peptides are available  along with MHC ClassII  molecules to the CD4 T cells
(3) Just as the virus enters into a cell, it takes on the host replicative machinery to manufactures  its proteins. Some of theses viral proteins are reduced into peptide fragments which are there along with class1 MHC molecules which therefore are recognised by the CD8 T cells. This guides to the differentiation  and activation of CD8 T cells to CD8+ T cells which produce apoptosis of the virus infected cells by the release of cytotoxic granules containing  perforins,granzymes, and cytokines such as interferons and TNF
