Researchers working on HIV (human immunodeficiency virus) and SIV (simian immunodeficiency virus) vaccines found that an antibody to a particular epitope of SIV (that was identical with the corresponding HIV-2 epitope) had a potent virus-neutralizing activity against numerous SIV and HIV-2 (but not HIV-1) isolates. This epitope was determined to be an octapeptide (= consisting of 8 amino acids linked in a polypeptide chain). This octapeptide was synthesized and used to immunize 20 individual rhesus macaques (Macaca mullata), but no protection against SIV in vivo was observed in the immunized animals. What could be the best explanation(s) for this peptide vaccine failure? Assess the following hypothetical explanations (1- 10) as either factually correct (= "true") or incorrect (= "false"):
1. The peptide could not be processed by dendritic cells.
2. The peptide could not be processed by B cells.
3. The peptide could not be processed by activated macrophages.
4. The vaccinations did not work, because the peptide was too long.
5. The vaccinations did not work, because the peptide was too short.
6. The vaccinations did not work, because the peptide was insufficiently complex.
7. The vaccinations did not work, because the induced cytokine response was too weak.
8. The vaccinations did not work, because T-cell epitopes were absent.
9. The vaccinations did not work, because the octapeptide failed to activate NK cells.
10. The vaccinations did not induce adequate amounts of interferon-? to activate professional antigen-presenting cells.