Virus-specific T cell receptor transgenic mice vaccinated with HSV-1 0ΔNLS limit HSV--induced corneal neovascularization in the absence of antibody

Abstract

Purpose : Humoral immunity is the correlate of protection against ocular HSV-1 infection in mice vaccinated with the HSV-1 0ΔNLS vaccine. The present study was undertaken to determine if the HSV-1 0ΔNLS vaccine provided efficacy in T cell receptor transgenic gBT-I.1 mice in which CD8⁺ T cells recognize the HSV-1 glycoprotein B (gB) peptide, gB_498-505 presented by MHC class I.

Methods : Male and female gBT-I.1 transgenic mice (6-12 weeks old) were vaccinated with HSV-1 0ΔNLS or vehicle (PBS) using a prime-boost regimen and subsequently challenged in the cornea with 1x10⁴ PFU HSV-1 McKrae. Cumulative survival was monitored over a 30 days, and viral content in the cornea and trigeminal ganglion (TG) was analyzed by plaque assay. Antibody neutralization titers (ANT) were assessed 30 days immediately prior to challenge and 30 days post-challenge. Leukocyte infiltration into the cornea and TG was assessed by flow cytometry. Corneal neovascularization was assessed by confocal microscopy. HSV-1 genome copy number was determined in mouse TG during latency by PCR. Pro-angiogenic factor content in the cornea was measured by suspension array analysis.

Results : HSV-1 0ΔNLS vaccinated gBT-I.1 mice were found to be resistant to HSV-1 challenge in terms of cumulative survival (p<.001, Mantel-Cox test) with little to no measureable ANT. Protection correlated with a reduction in infectious virus recovered in the TG but not cornea of vaccinated mice at day 7 post infection (pi). There were no differences in the number of total T cells including gB-specific CD8⁺ T cells or in myeloid cell populations recruited to the cornea or TG comparing vehicle- to HSV-1 0ΔNLS- vaccinated mice. Vaccination with HSV-1 0 ΔNLS did not impact the establishment of neuronal latency in gBT-I.1 mice. However, there was a dramatic difference in the neovascularization with little corneal hem- or lymph-angiogenesis in HSV-1 0ΔNLS vaccinated mice compared to vehicle controls (p<.01, Mann-Whitney U test). This phenotype was consistent with a significant reduction in the expression of IL-6 and VEGF-A but not FGF2 or HGF captured at day 7 pi.

Conclusions : These findings underscore a protective function of CD8⁺ T cells against corneal neovascularization provoked by HSV-1 but also illustrate gB-specific CD8 T cells are unable to prevent neuronal infection during acute infection.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.