Efficacy of Recombinant Herpes Simplex Virus 1 Glycoprotein D Candidate Vaccines in Mice

Abstract

To compare the immunogenity of the herpes simplex virus 1 (HSV-1/HHV-1) recombinant glycoprotein D (gD1), as a potential protective vaccine, Balb/c mice were immunized with either gD1/313 (the ectodomain of the gD1 fusion protein consisting of 313 amino acid residues), or the plasmid pcDNA3.1-gD (coding for a full length gD1 protein, FLgD1). A live attenuated HSV-1 (deleted in the gE gene), and a HSV-1 (strain HSZP)-infected cell extract served as positive controls, and three non-structural recombinant HSV-1 fusion proteins (ICP27, UL9/OBP and thymidine kinase--TK) were used as presumed non-protective (negative) controls. Protection tests showed that the LD50 value of the challenging infectious virus increased 90-fold in mice immunized with ICP27, but remained unchanged in other control mice immunized with TK and OBP polypeptides. A significant protection (the LD50 value of challenging virus increased 800-fold) was noted following immunization with gD1/313, while immunization with the gE-del virus and/or the gD1 DNA vaccine resulted in a more than 4,000-fold increase of the challenging virus dose killing 50% of the animals. Using ELISA, elevated antibody titers were detected following immunizations with gD1/313, gE-del virus, and/or HSV-1-infected-cell extract. In addition, all of the three non-structural proteins elicited a good humoral response (with titres ranging from 1:16,000 to 1:128,000). The lowest IgG response (1:8,000) was noted after immunization with the gD1 DNA vaccine. Peripheral blood leukocytes (PBLs) as well as splenocytes from mice immunized with gD1/313, gE-del virus, and gD1-plasmid responded in lymphocyte transformation test (LTT) to the presence of purified gD1/313 antigen. For PBLs, the most significant stimulation of thymidine incorporation was registered at a gD1/313 concentration of 5 microg/100 microl, while the splenocytes from DNA vaccine-immunized mice responded already at a concentration of 1 microg/100 microl.

Herpes Simplex Virus 1 and 2 Vaccine Design: What can we Learn from the Past?

“…The next step of HSV vaccine development proceeded from purified (nearly cell DNA-free) subunit vaccines to those composed of recombinant HSV-1/HSV-2 polypeptides [86][87][88][89][90]. Great majority of the recombinant vaccines contained the gB and/or gD polypeptides, and their efficacy was done in mice.…”

“…In addition, the authors also showed that the animals were resistant to the challenge with a lethal HSV dose. Later on, the recombinant proteins were prepared by transfection of plasmids (carrying the gD and/or gB ORFs) into competent Escherichia coli cells, which expressed the corresponding not glycosylated polypeptides [90,[95][96][97][98][99][100]. Recombinant glycoproteins (including gC) were also prepared in insect and/or mammalian cells, in which the recombinant products could be glycosylated [101].…”

“…Many classical plasmid DNA vaccines were prepared with the inserted HSV DNA fragment. The majority of them encoded HSV-1 and/or HSV-2 glycoproteins such as gB, gD, gC, and gE; their efficacy was tested in mice, guinea pigs, and rabbits [90,[118][119][120][121][122][123][124]. The results were obtained after immunization with plasmids encoding the glycoproteins gD and/or gB of either HSV-1 or HSV-2 alone or in combination.…”