Is viral protein expression important for peptide vaccine?
To find candidate proteins which can be used as peptide vaccine, these need to fulfill some criteria:


The most important is that the peptide (or protein) used for
vaccination shall not have a closely relate sequence in the organism 
in which the vaccination shall occur. Otherwise either no reaction
(due to immunologic tolerance to self) or an autoimmune reaction
might happen.
The peptide/protein need to be expressed on the surface of the
microbe (either virus or bacteria) since otherwise it will not be
recognized by the immune system. Also domains of a potential vaccine
candidate which are inside of membrane are not useful.
The epitope needs to be stable enough to be used as a vaccine and
also be present on the microbe (otherwise there is no immune
reaction).


If you want to read further on this topic, there is an interesting Paper from the WHO available, which gives a nice introduction:


Guidelines for the production and quality control of synthetic
peptide vaccines


To answer your question: No, these proteins cannot be used for this purpose, as they are relatively closely related to the same proteins in the human body. This will probably lead to no immunologic reaction at all. Additionally, these proteins are located inside of cells and thus not exposed to the immune system.