CpG is a TLR-9 agonist that would enhance innate immunity, antibody responses and polarize cell-mediated immunity to a Th1 response, which is preferable for virus infections.42 While CpG induces various components of the innate immune response, the response should be dissipated by 21–28 days after stimulation.43 This evidence concerns the gene TLR9 and viral infectious disease.