RESUMO
CMV tegument protein pp65 and CMV immediate early gene product IE1 are both considered immunodominant targets of cell-mediated immunity (CMI) and potentially capable of controlling CMV infection. To better assess their role in host defense, we have constructed a novel MVA transfer vector named pZWIIA and generated a recombinant MVA (rMVA) expressing both full-length pp65 and exon4 of IE1 (pp65-IE1-MVA) at high levels, followed by the genetic removal of the bacterial marker gene used to distinguish recombinant forms. Immunogenicity evaluation indicates that pp65-IE1-MVA not only can induce robust primary CMI to both antigens in HLA A2.1 Tg mice, but also can stimulate vigorous expansion of memory T lymphocyte responses to pp65 and IE1 in PBMC of CMV-positive donors. These properties make the MVA-based vaccine ideal for the dual role of priming and boosting CMV-specific T cell immunity as a means to control CMV disease in recipients of hematopoietic cell or solid organ transplantation (HCT or SOT). pZWIIA alone or in combination with other MVA transfer vectors can be used to generate MVA based multiple-antigen vaccine which have application in vaccine development for a wide spectrum of infectious diseases and cancer.
Assuntos
Proteínas Imediatamente Precoces/imunologia , Fosfoproteínas/imunologia , Vacinas de DNA/imunologia , Vacínia/imunologia , Proteínas da Matriz Viral/imunologia , Proteínas Virais/imunologia , Animais , Embrião de Galinha , Vetores Genéticos/genética , Humanos , Proteínas Imediatamente Precoces/biossíntese , Proteínas Imediatamente Precoces/sangue , Leucócitos Mononucleares/imunologia , Camundongos , Camundongos Transgênicos , Fosfoproteínas/biossíntese , Fosfoproteínas/sangue , Plasmídeos/genética , Linfócitos T/imunologia , Vacinas de DNA/biossíntese , Vacinas de DNA/genética , Vacínia/genética , Proteínas da Matriz Viral/biossíntese , Proteínas da Matriz Viral/sangue , Proteínas Virais/biossíntese , Proteínas Virais/sangueRESUMO
Human cytomegalovirus (CMV) is a viral pathogen that infects both genders, who remain asymptomatic unless they receive immunosuppressive drugs or acquire infections that cause reactivation of latent virus. CMV infection also causes serious birth defects following primary maternal infection during gestation. A safe and effective vaccine to limit disease in this population continues to be elusive. A well-studied antigen is glycoprotein B (gB), which is the principal target of neutralizing antibodies (NAb) towards CMV in humans and has been implicated as the viral partner in the receptor-mediated infection by CMV in a variety of cell types. Antibody-mediated virus neutralization has been proposed as a mechanism by which host immunity could modify primary infection. Towards this goal, an attenuated poxvirus, modified vaccinia virus Ankara (MVA), has been constructed to express soluble CMV gB (gB680-MVA) to induce CMV NAb. Very high levels of gB-specific CMV NAb were produced after two doses of the viral vaccine. NAb were durable within a twofold range for up to 6 months. Neutralization titers developed in immunized mice are equivalent to titers found clinically after natural infection. This viral vaccine, expressing gB derived from CMV strain AD169, induced antibodies that neutralized CMV strains of three different genotypes. Remarkably, preexisting MVA and vaccinia virus (poxvirus) immunity did not interfere with subsequent immunizations of gB680-MVA. The safety characteristics of MVA, combined with the robust immune response to CMV gB, suggest that this approach could be rapidly translated into the clinic.