H. Ghiasi

The importance of MHC-I and MHC-II responses in vaccine efficacy against lethal herpes simplex virus type 1 challenge.

To investigate the importance of major histocompatability complex (MHC) class I‐ and MHC class II‐dependent immune responses in herpes simplex virus‐1 (HSV‐1) vaccine efficacy, groups of β2m°/° (MHC I–) and Ab°/° (MHC II–) mice were inoculated with various vaccines, and then challenged intraperitoneally with HSV‐1. Following vaccination with either live avirulent HSV‐1, expressed HSV‐1 glycoprotein D (gD), or a mixture of seven expressed HSV‐1 glycoproteins (7gPs), Ab°/° (MHC‐II–) mice developed no enzyme‐linked immunosorbent assay (ELISA) or neutralizing antibody titres. In contrast, significant ELISA and neutralizing antibody titres were induced in β2m°/° (MHC‐I–) mice by all three vaccines. The neutralizing antibody titres were similar for all three vaccines, but were only ≈ 1/4 to 1/3 of that developed in C57BL/6 (parental) mice vaccinated with the same antigens. All three vaccines protected 100% of the wild‐type C57BL/6 mice against lethal challenge with 2×107 plaque‐forming units (PFU) of HSV‐1. The live virus vaccine and the 7gPs vaccine also protected 80% of the β2m°/° mice against the same lethal HSV‐1 challenge dose. In contrast, in Ab°/° mice, none of the vaccines provided significant protection against the same lethal challenge dose of HSV‐1. However, at a lower challenge dose of 2×106 PFU, all three vaccines protected 70–80% of the vaccinated Ab°/° mice (compared to only 10% survival in mock vaccinated controls). Thus, vaccination provided some protection against lethal HSV‐1 challenge in both β2m°/° and Ab°/° mice; however, the protection was less than that seen in the parental C57BL/6 mice. In addition, Ab°/° mice were less well protected by vaccination than were β2m°/° mice. Our results suggest that (1) both MHC‐I and MHC‐II are involved in vaccine efficacy against HSV‐1 challenge; (2) both types of responses must be present for maximum vaccine efficacy; and (3) the MHC‐II‐dependent immune response appeared to be more important than the MHC‐I‐dependent immune response for vaccine efficacy against HSV‐1 challenge.

Expression and characterization of baculovirus expressed herpes simplex virus type 1 glycoprotein L

SummaryWe have constructed a recombinant baculovirus expressing high levels of the herpes simplex virus type 1 (HSV-1) glycoprotein L (gL) in Sf9 cells. Sf9 cells infected with this recombinant virus synthesized three polypeptides of 26–27 kDa 28 kDa, and 31 kDa. The 28 and 31 kDa species were sensitive to tunicamycin and N-glycosidase F (PNGase F) treatment, suggesting that they were glycosylated. As shown by both indirect immunofluorescence and Western blot analysis, using polyclonal antibodies to synthetic gL peptides indicated that the baculovirus expressed gL was abundant on the surface of baculovirus gL infected Sf9 cells. A small fraction of the 31 kDa polypeptide was secreted into the extracellular medium as judged by Western blot analysis. The secreted form of gL was completely resistant to Endoglycosidase H (Endo-H), while the membrane associated form of gL was only partially resistant to Endo-H treatment, suggesting that the secreted gL represented a subpopulation of the membrane bound gL. Mice vaccinated with baculovirus expressed gL produced serum antibodies that reacted with authentic HSV-1 gL. However, these mice produced no HSV-1 neutralizing antibody (titer <1: 10) and they were not protected from lethal intraperitoneal or lethal ocular challenge with HSV-1. Thus, when used as a vaccine in the mouse model, gL, similar to our findings with HSV-1 gH, but unlike our results with the other 6 HSV-1 glycoproteins that we have expressed in this baculovirus system, did not provide any protection against HSV-1 challenge.