Diversity of the CD8 + T-Cell Response to Herpes Simplex Virus Type 2 Proteins among Persons with Genital Herpes

Abstract

ABSTRACT Cytolytic T cells play a major role in controlling herpes simplex virus type 2 (HSV-2) infections in humans. In an effort to more thoroughly evaluate the response to HSV-2 directly, ex vivo, we developed an enzyme-linked immunospot (ELISPOT) assay that utilized pools of overlapping synthetic peptides presented by autologous dendritic cells to purified CD8 + T cells. Donor response rates to individual open reading frames (ORFs) ranged from fewer than 5% responding to as many as 70% responding, with the greatest frequency of responses (by ORF) being directed against UL39, UL25, UL27, ICP0, UL46, and UL47 in descending order of frequency. HSV-2-seropositive subjects responded to as few as 3 or as many as 46 of the 48 ORFs tested, with a median of 11 ORFs recognized. HLA-B*07 expression correlated with stronger responses overall that were directed primarily against UL49 and UL46. Cumulative precursor frequencies in the blood ranged from 500 to almost 6,000 HSV-2 spot-forming units/10 6 CD8 + T cells. The magnitude and breadth of the response in the infected population were greater than previously appreciated. Whether this variability in the CD8 + T-cell response within individuals is associated with the frequency of viral reactivation warrants further study.