Anti-Vector Immune Response Formed after Immunization with Recombinant Vaccines Based on the Vaccinia Virus, MVA Strain

The search for safe approaches to primary immunization of the adult population under the absence of herd immunity to orthopoxviruses, when re-initiation of smallpox vaccination campaign is required, is currently very relevant. Thereat, the clinical trials of recombinant vaccines based on the vaccinia virus, MVA strain, against different illnesses confirm that they are safe for humans and in addition to target efficiency (capacity to induce immunity to proteins expressed by embedded foreign genes), show immunogenicity to vector – vaccinia virus. The aim of the review was to evaluate anti-vector immunity level in people immunized by recombinant viral vaccines, based on vaccinia virus, MVA strain. Explicit experimental data on the level of anti-vector immunity in response to immunization with recombinant vaccines in different countries of the world are presented. Those studies were mainly carried out with recombinants containing embedded immunodominant genes of human immunodeficiency virus (HIV), as the number of works on the creation of recombinant vaccines expressing the antigen determinants of HIV significantly exceeds the number of those on recombinant preparations based on vaccinia virus; the vaccines are successfully used in medical practice and are safe even for people with immunodeficiency conditions. The results obtained indicated an increase in anti-vector immunity with escalation of vaccine dose and peak indicators after two immunizations. Further injections of the vaccine did not lead to increase in the virus neutralizing antibodies, their production gradually decreased over a period of one year or more. In addition to the humoral immune response, cellular anti-vector immunity, represented mainly by CD8 + T-cells, was induced. The insertion of foreign genes did not affect the formation of anti-vector immunity, just as its level did not affect the development of humoral and cellular immune responses to proteins expressed by the embedded genes. Comparative characterization of the anti-vector immunity indices after immunization with recombinant vaccines and specific immunity in response to the IMVAMUNE® vaccine showed that their levels either corresponded to each other, or in the first case the values were even higher.