Gordy, J. | bioRxiv Science

bioRxiv2019

A Vaccine Composed of Antigen Fused to a Ligand for a Receptor on Immature Dendritic Cells Elicits Protective Antibody Responses to Malaria Sporozoites in Infant Macaques

Infants and young children are the groups at greatest risk for severe disease resulting from Plasmodium falciparum infection. We previously demonstrated in mice that a protein vaccine composed of the chemokine macrophage inflammatory protein 3 genetically fused to the minimally truncated circumsporozoite protein of P. falciparum (MCSP) elicits high concentrations of specific antibody and significant reduction of liver sporozoite load in a mouse model system. In the current study, a squalene based adjuvant (AddaVax, InvivoGen, San Diego, Ca) equivalent to the clinically approved MF59 (Seqiris, Maidenhead, UK) elicited greater antibody responses in mice than the previously employed adjuvant polyinosinic:polycytidylic acid, ((poly(I:C), InvivoGen, San Diego, Ca) and the clinically approved Aluminum hydroxide gel (Alum, Invivogen, San Diego, Ca) adjuvant. Use of the AddaVax adjuvant also expanded the range of IgG subtypes elicited by mouse vaccination. Sera passively transferred into mice from MCSP/AddaVax immunized one and six month old macaques significantly reduced liver sporozoite load upon sporozoite challenge. Protective antibody concentrations attained by passive transfer in the mice were equivalent to those observed in infant macaques 18 weeks after the final immunization. The efficacy of this vaccine in a relevant non-human primate model indicates its potential usefulness for the analogous high risk human population.

immunology↗

bioRxiv2019

IFN-alpha and 5-Aza-2-deoxycytidine enhance the anti-tumor efficacy of a dendritic-cell targeting MIP3alpha-Gp100-Trp2 DNA vaccine by affecting T-cell recruitment and tumor microenvironment gene expression

BackgroundThe chemokine MIP-3 (CCL20) binds to CCR6 found on immature dendritic cells. DNA vaccines fusing MIP-3 to melanoma-associated antigens have shown improved efficacy and immunogenicity in the B16F10 model. To optimize the therapy, our laboratory has added agents designed to overcome immunoregulatory mechanisms of the tumor microenvironment. Here, we report that the combination of type-I interferon therapy (IFN) with 5-Aza-2-deoxycitidine (Aza) profoundly enhanced the therapeutic anti-melanoma efficacy of a MIP-3-Gp100-Trp2 DNA vaccine. MethodsThe current studies utilize the B16F10 syngeneic mouse melanoma model. The vaccine is administered intramuscularly (i.m.) followed by i.m. electroporation. Vaccinations are given thrice at one-week intervals beginning day 5 with CpG adjuvant given two days later as noted. Aza is given i.p. at 1mg/kg on days 5 and 12. IFN therapy is given in a series of one high followed by three low doses, beginning on days 5 and 12. Tumor sizes, growth, and survival were all assessed. Tumor microenvironment gene expression levels were explored by qRT-PCR. Tumor-infiltrating lymphocytes (TILs) were assessed by stimulating the purified lymphocyte fraction of tumors with vaccine antigens followed by intracellular cytokine staining flow cytometry. ResultsWe demonstrate that the addition of IFN and Aza treatments to mice vaccinated with the MIP-3-Gp100-Trp2 vaccine has led to significantly reduced tumor burden and overall increases in mouse survival, increasing median survival by 39% over vaccine and 86% over controls. Importantly, this increase in efficacy was dependent on the presence of all three components: vaccine, IFN, and Aza. The addition of Aza and IFN to the vaccine increased T-cell tumor infiltration and altered the proportion of CD8+T-cells. Also, IFN and vaccine induced durable changes in IFN-stimulated gene transcription. ConclusionsEfficient targeting of antigen to immature dendritic cells with a chemokine-fusion vaccine offers a potential alternative approach to classic and dendritic cell based vaccines currently undergoing clinical investigation. Combining this approach with IFN and Aza combination treatment significantly improved vaccine efficacy, with efficacy correlating with changes in TILs and in IFN -stimulated gene expression. Further potential therapy optimization currently undergoing investigation offers promise for this line of investigation to become a novel melanoma therapy.

immunology↗