A comparison of T cell responses to glycoprotein B (gB-1) of herpes simplex virus type 1 and its non-glycosylated precursor protein, pgB-1

Glycoprotein B from strain 17 of herpes simplex virus type I contains an invariant chain homologous sequence that binds to MHC class II molecules

Major histocompatibility complex class I (MHCI) molecules are major targets of virus evasion strategies because they introduce antigens from the biosynthesis pathway into the antigen-processing and presentation pathways for immune recognition by CD8+ T cells. Little is known about viral strategies that interfere with the MHC class II (MHCII) antigen presentation pathway. We identified a six amino acid sequence from type I herpes simplex virus (HSV-1) glycoprotein B (gB) that is identical to a sequence of human leucocyte antigen D (HLA-D) -associated invariant chain (Ii). In addition, this gB sequence is adjacent to a highly conserved HLA-DR1 binding motif. Both viral sequences together resemble the class II binding site of human Ii, consisting of a MHCII groove binding segment and a promiscuous binding site. We cloned gB from HSV-1 strain 17 and demonstrate association of the virus envelope protein to three HLA-DR allotypes. With chimeric Ii/gB fusion proteins we identified gB sequences that mediate promiscuous or allotype-specific binding to the HLA-DR peptide-binding domain. Mutation of two Lys residues in the viral segment of Ii/gB abolished promiscuous binding to HLA-DR heterodimers. The result indicates promiscuous binding of the virus sequence to HLA-DR molecules and suggests a potential for HSV-1 to manipulate antigen processing and presentation.

Immunological investigation of adult patients with primary herpes simplex virus-1 infection

Peripheral blood mononuclear cell parameters were examined in 17 adult patients with primary herpes simplex virus-1 (HSV-1) infection. Two-color flow cytometry revealed an increase in HLA-DR+ T cell and Leu8+ T cell subsets, and a decrease in CD57+CD16+ subset in the patients. In the symptomatic phase of HSV-1 infection, serum interferon gamma (IFN-gamma) level increased in many patients, and the mean serum level in the patients (0.26 +/- 0.12 U/ml) was significantly higher than the mean control level (0.14 +/- 0.06 U/ml). Soluble intercellular adhesion molecule-1 (sICAM-1) in patients' serum also was increased to a mean level of 398 +/- 130 ng/ml at the first visit. Both the IFN-gamma and sICAM-1 levels fell to near the control levels after the disappearance of oral inflammation. Natural killer (NK) activity was at first increased (mean 46.1 +/- 17.9%), and later decreased to the control level (mean 38.4 +/- 10.6%). In contrast, lymphokine activated killer (LAK) activity at the first visit (mean 53.2 +/- 15.7%) was significantly lower than the control level (mean 69.5 +/- 10.3%). PHA- or ConA-stimulated lymphocytes from the patients incorporated less thymidine than control lymphocytes. These reduced lymphocyte reactivities recovered to the control levels after the disappearance of the acute infection. These results indicate some of the characteristics of lymphocyte pathophysiology in primary HSV-1 infection.