Noncognate Signals Drive Enhanced Effector CD8 ⁺ T Cell Responses through an IFNAR1-Dependent Pathway after Infection with the Prototypic Vaccine, 0ΔNLS, against Herpes Simplex Virus 1

Abstract

Previous studies by our group identified a highly efficacious vaccine 0ΔNLS (deficient in the nuclear localization signal of infected cell protein 0) against HSV-1 in an experimental ocular mouse model. However, details regarding fundamental differences in the initial innate and adaptive host immune response were not explored. Here, we present a side-by-side analysis of the primary infection characterizing differences of the host immune response in mice infected with 0ΔNLS versus the parental, GFP105. The results show that local viral infection and replication are controlled more efficiently in mice exposed to 0ΔNLS versus GFP105 but clearance of infectious virus is equivalent comparing the two groups. Moreover, the 0ΔNLS-infected mice displayed enhanced effector CD8 + but not CD4 + T cell responses from the draining lymph nodes at day 7 post infection measured by IFN-γ and TNF-α production along with changes in cell metabolism. The increased effector function of CD8 + T cells from 0ΔNLS-infected mice was not driven by changes in antigen presentation but lost in the absence of a functional type I IFN pathway. These results are further supported by enhanced local expression of type I IFN and IFN-inducible genes along with increased IL-12 production by CD8α + DCs in the draining lymph nodes of 0ΔNLS-infected mice compared to the GFP105-infected animals. It was also noted the recall to HSV-1 antigen by CD8 + T cells was elevated in mice infected with HSV-1 0ΔNLS compared to GFP105. Collectively, the results underscore the favorable qualities of HSV-1 0ΔNLS as a candidate vaccine against HSV-1 infection. IMPORTANCE Cytotoxic T lymphocytes (CTLs) play a critical role in the clearance for many viral pathogens including herpes simplex virus 1 (HSV-1). Here, we compared the cellular innate and adaptive immune response in mice infected with an attenuated HSV-1 (0ΔNLS) found to be a highly successful experimental prophylactic vaccine to parental HSV-1 virus. We found that CD8 + T cell effector function is elevated in 0ΔNLS-infected mice through noncognate signals including IL-12 and type I interferon (IFN) pathways along with changes in CD8 + T cell metabolism whereas other factors including cell proliferation, co-stimulatory molecule expression and antigen presentation were dispensable. Thus, an increase in CTL activity established by exposure to HSV-1 0ΔNLS in comparison to parental HSV-1 likely contributes to the efficacy of the vaccine and underscores the nature of the attenuated virus as a vaccine candidate for HSV-1 infection.

HSV-1 0∆NLS vaccine elicits a robust B lymphocyte response and preserves vision without HSV-1 glycoprotein M or thymidine kinase recognition

“…Previously, we reported 0∆NLS-vaccinated mice displayed more functional HSV-1 gB-specific CD8 + T cells 7 days post-vaccination compared to mice immunized with GFP105 38 . Similar to the experimental design above, we wished to determine whether this relationship held following the booster immunization, mice vaccinated with GFP105 or 0∆NLS were evaluated for IFN-γ-secreting, HSV-1 gB-specific CD8 + T cells at 21 days post-primary immunization and 30 days post-boost.…”

“…Still, another cytokine IL-12, has been shown to promote differentiation of naive B cells into plasma cells 60 . In a previous study, we reported following initial vaccination with HSV-1 0∆NLS, an elevation in type I IFN and IL-12 production by cells was noted which drove an increase in IFN-γ-expressing CD8 + T cells in comparison to mice vaccinated with GFP105 38 . Thus, using the same vaccination model, changes in B cell subset formation may be linked to an altered cytokine microenvironment.…”

“…One million spleen- or PLN-derived cells were resuspended in 100ul of SB and stained for the following cell population: follicular CD4 + T cells (CD45 + CD3 + CD4 + PD-1 + CXCR5 + Bcl-6 + ), germinal B cells (CD45 + CD19 + GL-7 + CD95 + ), plasma cells (CD45 + B220 low CD138 + ), plasmablasts (CD19 + CD138 + ) class-switched B cells (CD45 + CD19 + IgM - IgD - ), subsets and effectors of regulatory B cells (Bregs): marginal zone B cells (CD45 + CD19 + CD23 + CD21 - ) and B10 (CD45 + CD19 + CD5 + CD1d high ). The samples with stained cells were acquired with MacsQuant flow cytometer (Miltenyi Biotec) or spectral flow cytometer Aurora (Cytek Biosciences, Fremont, CA) as described previously 38 . For assessment of HSV-1 gB-specific CD8 + T cell function, we utilized a procedure previously described by our group 74 .…”

“…ELISPOT for IFN-γ was described previously 38 . Briefly, 96-plate with immobilon-P membrane were coated overnight with primary IFN-γ Ab (BD Biosciences).…”

“…Cells isolated from spleen of mice harvested at day 21 and at day 30 after boost, were plated at concentration 5 × 10 5 cells per well followed by overnight re-stimulation with HSV-1 derived gB peptide, SSIEFARL (10 ug/ml). The plate was developed as described previously 38 .…”