Dataset Information

A cytomegalovirus DNA vaccine induces antibodies that block viral entry into fibroblasts and epithelial cells.

ABSTRACT: A vaccine to prevent congenital cytomegalovirus (CMV) infections is a national priority. Investigational vaccines have targeted the viral glycoprotein B (gB) as an inducer of neutralizing antibodies and phosphoprotein 65 (pp65) as an inducer of cytotoxic T cells. Antibodies to gB neutralize CMV entry into all cell types but their potency is low compared to antibodies that block epithelial cell entry through targeting the pentameric complex (gH/gL/UL128/UL130/UL131). Hence, more potent overall neutralizing responses may result from a vaccine that combines gB with pentameric complex-derived antigens. To assess the ability of pentameric complex subunits to generate epithelial entry neutralizing antibodies, DNA vaccines encoding UL128, UL130, and/or UL131 were formulated with Vaxfectin(®), an adjuvant that enhances antibody responses to DNA vaccines. Mice were immunized with individual DNA vaccines or with pair-wise or trivalent combinations. Only the UL130 vaccine induced epithelial entry neutralizing antibodies and no synergy was observed from bi- or trivalent combinations. In rabbits the UL130 vaccine again induced epithelial entry neutralizing antibodies while UL128 or UL131 vaccines did not. To evaluate compatibility of the UL130 vaccine with DNA vaccines encoding gB or pp65, mono-, bi-, or trivalent combinations were evaluated. Fibroblast and epithelial entry neutralizing titers did not differ between rabbits immunized with gB alone vs. gB/UL130, gB/pp65, or gB/UL130/pp65 combinations, indicating a lack of antagonism from coadministration of DNA vaccines. Importantly, gB-induced epithelial entry neutralizing titers were substantially higher than activities induced by UL130, and both fibroblast and epithelial entry neutralizing titers induced by gB alone as well as gB/pp65 or gB/UL130/pp65 combinations were comparable to those observed in sera from humans with naturally-acquired CMV infections. These findings support further development of Vaxfectin(®)-formulated gB-expressing DNA vaccine for prevention of congenital CMV infections.

SUBMITTER: McVoy MA

PROVIDER: S-EPMC4684450 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A cytomegalovirus DNA vaccine induces antibodies that block viral entry into fibroblasts and epithelial cells.

McVoy Michael A MA Lee Ronzo R Saccoccio Frances M FM Hartikka Jukka J Smith Larry R LR Mahajan Rohit R Wang Jian Ben JB Cui Xiaohong X Adler Stuart P SP

Vaccine 20151024 51

A vaccine to prevent congenital cytomegalovirus (CMV) infections is a national priority. Investigational vaccines have targeted the viral glycoprotein B (gB) as an inducer of neutralizing antibodies and phosphoprotein 65 (pp65) as an inducer of cytotoxic T cells. Antibodies to gB neutralize CMV entry into all cell types but their potency is low compared to antibodies that block epithelial cell entry through targeting the pentameric complex (gH/gL/UL128/UL130/UL131). Hence, more potent overall ne ...[more]

PMID: 26597035

Similar Datasets

Project description:Cytomegalovirus (CMV) entry into fibroblasts differs from entry into epithelial cells. CMV also spreads cell to cell and can induce syncytia. To gain insights into these processes, 27 antibodies targeting epitopes in CMV virion glycoprotein complexes, including glycoprotein B (gB), gH/gL, and the pentamer, were evaluated for their effects on viral entry and spread. No antibodies inhibited CMV spread in fibroblasts, including those with potent neutralizing activity against fibroblast entry, while all antibodies that neutralized epithelial cell entry also inhibited spread in epithelial cells and a correlation existed between the potencies of these two activities. This suggests that exposure of virions to the cell culture medium is obligatory during spread in epithelial cells but not in fibroblasts. In fibroblasts, the formation of syncytiumlike structures was impaired not only by antibodies to gB or gH/gL but also by antibodies to the pentamer, suggesting a potential role for the pentamer in promoting fibroblast fusion. Four antibodies reacted with linear epitopes near the N terminus of gH, exhibited strain specificity, and neutralized both epithelial cell and fibroblast entry. Five other antibodies recognized conformational epitopes in gH/gL and neutralized both fibroblast and epithelial cell entry. That these antibodies were strain specific for neutralizing fibroblast but not epithelial cell entry suggests that polymorphisms external to certain gH/gL epitopes may influence antibody neutralization during fibroblast but not epithelial cell entry. These findings may have implications for elucidating the mechanisms of CMV entry, spread, and antibody evasion and may assist in determining which antibodies may be most efficacious following active immunization or passive administration.IMPORTANCE Cytomegalovirus (CMV) is a significant cause of birth defects among newborns infected in utero and morbidity and mortality in transplant and AIDS patients. Monoclonal antibodies and vaccines targeting humoral responses are under development for prophylactic or therapeutic use. The findings reported here (i) confirm that cell-to-cell spread of CMV is sensitive to antibody inhibition in epithelial cells but not fibroblasts, (ii) demonstrate that antibodies can restrict the formation in vitro of syncytiumlike structures that resemble syncytial cytomegalic cells that are associated with CMV disease in vivo, and (iii) reveal that neutralization of CMV by antibodies to certain epitopes in gH or gH/gL is both strain and cell type dependent and can be governed by polymorphisms in sequences external to the epitopes. These findings serve to elucidate the mechanisms of CMV entry, spread, and antibody evasion and may have important implications for the development of CMV vaccines and immunotherapeutics.

Project description:UnlabelledHuman cytomegalovirus (HCMV) elicits neutralizing antibodies (NAb) of various potencies and cell type specificities to prevent HCMV entry into fibroblasts (FB) and epithelial/endothelial cells (EpC/EnC). NAb targeting the major essential envelope glycoprotein complexes gB and gH/gL inhibit both FB and EpC/EnC entry. In contrast to FB infection, HCMV entry into EpC/EnC is additionally blocked by extremely potent NAb to conformational epitopes of the gH/gL/UL128/130/131A pentamer complex (PC). We recently developed a vaccine concept based on coexpression of all five PC subunits by a single modified vaccinia virus Ankara (MVA) vector, termed MVA-PC. Vaccination of mice and rhesus macaques with MVA-PC resulted in a high titer and sustained NAb that blocked EpC/EnC infection and lower-titer NAb that inhibited FB entry. However, antibody function responsible for the neutralizing activity induced by the MVA-PC vaccine is uncharacterized. Here, we demonstrate that MVA-PC elicits NAb with cell type-specific neutralization potency and antigen recognition pattern similar to human NAb targeting conformational and linear epitopes of the UL128/130/131A subunits or gH. In addition, we show that the vaccine-derived PC-specific NAb are significantly more potent than the anti-gH NAb to prevent HCMV spread in EpC and infection of human placental cytotrophoblasts, cell types thought to be of critical importance for HCMV transmission to the fetus. These findings further validate MVA-PC as a clinical vaccine candidate to elicit NAb that resembles those induced during HCMV infection and provide valuable insights into the potency of PC-specific NAb to interfere with HCMV cell-associated spread and infection of key placental cells.ImportanceAs a consequence of the leading role of human cytomegalovirus (HCMV) in causing permanent birth defects, developing a vaccine against HCMV has been assigned a major public health priority. We have recently introduced a vaccine strategy based on a widely used, safe, and well-characterized poxvirus vector platform to elicit potent and durable neutralizing antibody (NAb) responses targeting the HCMV envelope pentamer complex (PC), which has been suggested as a critical component for a vaccine to prevent congenital HCMV infection. With this work, we confirm that the NAb elicited by the vaccine vector have properties that are similar to those of human NAb isolated from individuals chronically infected with HCMV. In addition, we show that PC-specific NAb have potent ability to prevent infection of key placental cells that HCMV utilizes to cross the fetal-maternal interface, suggesting that NAb targeting the PC may be essential to prevent HCMV vertical transmission.

Project description:Human cytomegalovirus (HCMV) induces a uniquely high frequency of virus-specific effector/memory CD8+ T-cells, a phenomenon termed "memory inflation". Thus, HCMV-based vaccines are particularly interesting in order to stimulate a sustained and strong cellular immune response against cancer. Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor with high lethality and inevitable relapse. The current standard treatment does not significantly improve the desperate situation underlining the urgent need to develop novel approaches. Although HCMV is highly fastidious with regard to species and cell type, GBM cell lines are susceptible to HCMV. In order to generate HCMV-based therapeutic vaccine candidates, we deleted all HCMV-encoded proteins (immunoevasins) that interfere with MHC class I presentation. The aim being to use the viral vector as an adjuvant for presentation of endogenous tumor antigens, the presentation of high levels of vector-encoded neoantigens and finally the repurposing of bystander HCMV-specific CD8+ T cells to fight the tumor. As neoantigen, we exemplarily used the E6 and E7 proteins of human papillomavirus type 16 (HPV-16) as a non-transforming fusion protein (E6/E7) that covers all relevant antigenic peptides. Surprisingly, GBM cells infected with E6/E7-expressing HCMV-vectors failed to stimulate E6-specific T cells despite high level expression of E6/E7 protein. Further experiments revealed that MHC class I presentation of E6/E7 is impaired by the HCMV-vector although it lacks all known immunoevasins. We also generated HCMV-based vectors that express E6-derived peptide fused to HCMV proteins. GBM cells infected with these vectors efficiently stimulated E6-specific T cells. Thus, fusion of antigenic sequences to HCMV proteins is required for efficient presentation via MHC class I molecules during infection. Taken together, these results provide the preclinical basis for development of HCMV-based vaccines and also reveal a novel HCMV-encoded block of MHC class I presentation.

Dataset Information

A cytomegalovirus DNA vaccine induces antibodies that block viral entry into fibroblasts and epithelial cells.

Publications

A cytomegalovirus DNA vaccine induces antibodies that block viral entry into fibroblasts and epithelial cells.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets