Generation of an Oncolytic Herpes Simplex Virus 1 Expressing Human MelanA

Abstract

Robust anti-tumor immunity requires innate as well as adaptive immune responses. We have shown that plasmacytoid dendritic cells develop killer cell-like activity in melanoma cell cocultures after exposure to the infectious but replication-deficient herpes simplex virus 1 (HSV-1) d106S. To combine this innate effect with an enhanced adaptive immune response, the gene encoding human MelanA/MART-1 was inserted into HSV-1 d106S via homologous recombination to increase direct expression of this tumor antigen. Infection of Vero cells using this recombinant virus confirmed MelanA expression by Western blotting, flow cytometry, and immunofluorescence. HSV-1 d106S-MelanA induced expression of the transgene in fibroblast and melanoma cell lines not naturally expressing MelanA. Infection of a melanoma cell line with CRISPR-Cas9-mediated knockout of MelanA confirmed de novo expression of the transgene in the viral context. Dependent on MelanA expression, infected fibroblast and melanoma cell lines induced degranulation of HLA-matched MelanA-specific CD8+ T cells, followed by killing of infected cells. To study infection of immune cells, we exposed peripheral blood mononuclear cells and in vitro-differentiated macrophages to the parental HSV-1 d106S, resulting in expression of the transgene GFP in CD11c+ cells and macrophages. These data provide evidence that the application of MelanA-encoding HSV-1 d106S could enhance adaptive immune responses and re-direct MelanA-specific CD8+ T cells to tumor lesions, which have escaped adaptive immune responses via downregulation of their tumor antigen. Hence, HSV-1 d106S-MelanA harbors the potential to induce innate immune responses in conjunction with adaptive anti-tumor responses by CD8+ T cells, which should be evaluated in further studies.

Pan-cancer analysis of RNA expression of ANGIOTENSIN-I-CONVERTING ENZYME 2 reveals high variability and possible impact on COVID-19 clinical outcomes

“…Initial data suggest that some cancers express high levels of ACE2 16 , 17 . In such cases, malignant masses could function as viral reservoirs, similar to observations related to other viruses, thus sustaining and amplifying SARS-CoV-2 infection in patients with cancer 18 , 19 . Additionally, increased co-expression of cellular proteases with ACE2 may further identify subsets of cancer patients with increased vulnerability to infection 20 , 21 .…”

Gold Nanoclusters Display Low Immunogenic Effect in Microglia Cells

“…In addition to size, concentrations, route of administration etc., an important factor which may determine NP activities is their coating. Thus, considering that glutathione was reported as anti-inflammatory agent [ 36 ] we cannot exclude that anti-inflammatory or the low-grade inflammatory activity of Au18 NCs results partially from glutathione coating. However, it remains little probable that glutathione is the key determinant of such activity as doses reported to act as anti-inflammatory were as high as 10 mM, which is 129 times more than 76,8 µM of glutathione concentration introduced as a coating of present Au18 NCs.…”

Prospect of Plasmacytoid Dendritic Cells in Enhancing Anti-Tumor Immunity of Oncolytic Herpes Viruses

“…So far, it is unclear whether the expression of tumor antigens or epitopes in the context of oncolytic viruses will actually contribute to the induction of tumor antigen-specific T-cells and may skew the immune reaction into a more pronounced CD8+ T-cell response. We have observed expression of HSV-1 d 106S-encoded GFP upon infection of CD11c+ cells and macrophages, but we were so far not able to detect HSV-1 d 106S-MelanA expression in antigen-presenting cells [74]. Therefore, this important point needs to be evaluated in further studies.…”

“…We hypothesized that the enhanced expression of a tumor-specific antigen in the context of an oncolytic herpes virus may favorably affect the process of cell killing. Since MelanA/MART-1 is the most frequent target of CD8+ T-cells responses against melanoma in vitro and in vivo [20,73], we constructed a HSV-1 d 106S-based oncolytic virus, which expressed the melanoma-associated antigen MelanA/MART-1 in melanoma cells not naturally expressing this tumor antigen [74]. When these cells were cocultured with an HLA-matched MelanA-specific CD8+ T-cell clone, we observed the activation and degranulation of T-cells, which resulted in significantly enhanced cell death upon infection with the MelanA-encoding HSV-1 d 106S (Figure 1).…”

“…Designing oncolytic HSV-1 to directly express tumor-related self- and neo-antigens may contribute to a vaccine-like approach resulting in a more efficient induction of cytotoxic T-cell responses. It may be helpful to express tumor-related antigens or epitopes by less virulent viruses, because cells which rapidly succumb to oncolytic effects may not efficiently express the genes of interest [74].…”