Table 1.

Herpes Vaccine Strategies.

Type of Vaccine	Vaccine Construct	Administration Route	Phase ofTrial	Virus Subtype	Results	Limitations	Ref.
Inactivated vaccine	HSV-1 gH deletion (SC16∆gH)	Subcutaneous in human	Clinical trial	HSV-2	Unable to show protection against acute or recurrent genital herpes infection Does not show improvement in recurrences and disease severity. Does not affect on viral shedding	Vaccine did not achieve clinical usefulness Alternative approaches could be proposed	(11) Akhrameyeva NV, Zhang P, Sugiyama N, Behar SM, Yao F. Development of a glycoprotein D- expressing dominant- negative and replication- defective herpes simplex virus 2 (HSV-2) recombinant viral vaccine against HSV-2 infection in mice. J Virol, 85(10), 5036-5047 (2011).
		Subcutaneous and intravaginal in guinea pig	Preclinical trial	HSV-2	Provides complete protection against primary and recurrent HSV infection Induces high neutralizing antibody titers Induces long- lasting immune responses i.e., over 6 months Develops high potency for complete HSV protection	Missing reproducibility on correlation between antibody titers and recurrent infection pattern The immune mechanisms involved in the control of recurrent infection need to be elucidated	(12) Reszka NJ, Dudek T, Knipe DM. Construction, and properties of a herpes simplex virus 2 dl5-29 vaccine candidate strain encoding an HSV-1 virion host shutoff protein. Vaccine, 28(15), 2754-2762 (2010)
		Intraepithelial and intravaginal in guinea pig	Preclinical trial	HSV-2	Reduces HSV symptoms Gives quicker symptomatic episodes Prevents local HSV-2 replication offers Improved protection against HSV severity via Intravaginal route	High risk of genetic recombination Unable to block the virus reactivation to prevent disease recurrences This study needs more animal experiment for statistical significance	(13) Belshe PB, Leone PA, Bernstein DI et al. Efficacy Results of a Trial of a Herpes Simplex Vaccine. The New England journal of medicine, 366, 34-43 (2012).
		Scarification via ear pinna route in mice	Preclinical trial	HSV-1	Establishes self-limiting HSV infection Induces DTH response Provides protection against acute HSV infection	May reactivate latent HSV Viral latency and reactivation should be studied in more suitable animal model	(14) Bernard MC, Barban V, Pradezynski F et al. Immunogenicity, protective efficacy, and non-replicative status of the HSV-2 vaccine candidate HSV529 in mice and guinea pigs. PLoS One, 10(4), e0121518 (2015).
	HSV-2 ICP8 replication defective + B7 co- stimulation	Subcutaneous in mice	Preclinical trial	HSV-2	Increases IFN-g-producing T- cells Decreases HSV replication in genital mucosa Lowers HSV related genital and neurological disease Reduces mortality	The protective immunity mediated by antibody and T- cells	(15, 16) Ohashi M, Bertke AS, Patel A, Krause PR. Spread of herpes simplex virus to the spinal cord is independent of spread to dorsal root ganglia. J Virol, 85(6), 3030-3032 (2011). Dasgupta G, Chentoufi AA, Kalantari M et al. Immunodominant "asymptomatic" herpes simplex virus 1 and 2 protein antigens identified by probing whole-ORFome microarrays with serum antibodies from seropositive asymptomatic versus symptomatic individuals. J Virol, 86(8), 4358-4369 (2012).
	Multiple genes Deletion of HSV-2	Subcutaneous in mice	Preclinical trial	HSV-2	Reduces viral titer and viral shedding Suppreses viral replication and latency Theorotically provides protection against double- mutant virus even in immunocompro mised individuals	The genetic basis underlying the latency defect should be elucidated	(17) Dasgupta G, Nesburn AB, Wechsler SL, BenMohamed L. Developing an asymptomatic mucosal herpes vaccine: the present and the future. Future Microbiol, 5(1), 1-4 (2010).
	HSV-2 ICP10∆PK deletion	Subcutaneous in mice	Preclinical trial	HSV-2	Induces memory T-cells and establish strong T-helper type 1 (Th1) immune response Increases IL-12 secretion by DCs	Does not readily begin latency Must show the frequency and duration of memory T-cells Assess the ability to activate p38MAPK in T- cells	(18) Chentoufi AA, BenMohamed L. Future viral vectors for the delivery of asymptomatic herpes epitope-based immunotherapeutic vaccines. Future virology, 5(5), 525-528 (2010).
	HSV-2 UL5 & UL29 genes deletion	Intramuscular in humans	Clinical trial	Multiple mutated HSV-1 and HSV-2 combina tions	Safe and well tolerated Produces neutralizing antibody along with CD4+ and CD8+ T-cell responses in HSV seronegative individuals Produces only CD4+ T-cell responses in HSV seropositive individuals	More reactions than placebo on the injection site Should modify vaccine by increasing the expression of certain viral proteins Should inhibits the expression of viral immune evasion genes, or adding an adjuvant	(19) Schiffer JT, Abu-Raddad L, Mark KE et al. Mucosal host immune response predicts the severity and duration of herpes simplex virus-2 genital tract shedding episodes. Proc Natl Acad Sci U. S. A., 107(44), 18973-18978 (2010).
		Subcutaneous, and intramuscular in mice	Preclinical trial	HSV-2	Decreases genital infection and viral shedding Produces strong immune response Gives protection against many HSV-2 viral strains Shows better protection via intramuscular route	Should study the role and type of DC involved in priming immunity against the intramuscular vaccine	(20) Chentoufi AA, Binder NR, Berka N et al. Asymptomatic human CD4+ cytotoxic T-cell epitopes identified from herpes simplex virus glycoprotein B. J Virol, 82(23), 11792-11802 (2008).
	HSV-2 gD (∆gD-2) deletion	Intramuscular in mice	Preclinical trial	HSV-2 and superin- fection (HSV-1+)	Induces IgG2 response Fully protects HSV-2 spreading to the sacral ganglia and mortality Shows almost no signs of disease	voir in the Should use guinea pigs as an animal model to study recurrent diseases Should incorporate murine superinfection model in preclinical evaluation of HSV- vaccine candidates	(21) Dervillez X, Qureshi H, Chentoufi AA et al. “Asymptomatic” HLA- A*02:01-Restricted Epitopes from Herpes Simplex Virus Glycoprotein B Preferentially Recall Polyfunctional CD8+ T Cells from Seropositive Asymptomatic Individuals and Protect HLA Transgenic Mice Against Ocular Herpes. J Immunol, (2013).
Live attenuated vaccine	R7017 Deletion of HSV-1 thymidine kinase	Intracerebral in mice, vaginal, intradermal, and intramuscular in guinea pigs and scarification of cornea in rabbits	Preclinical trial	HSV-1 and HSV-2	Protects against severe HSV infections HSV lesions are localized, superficial and heals more rapidly	It establishes low frequency of latent infections in all hosts (R7020) It also establishes latent infection in rabbits (R7017)	(22) Dervillez X, Gottimukkala C, Kabbara KW et al. Future of an "Asymptomatic" T-cell Epitope-Based Therapeutic Herpes Simplex Vaccine. Future virology, 7(4), 371-378 (2012).
	RAV9395 (Deletion of HSV-2 γ134.5 gene, UL55 and UL56 ORF)	Intramuscular	Preclinical trial	HSV-2	Decreases lesion development and HSV infection severity Decreases frequency of HSV reactivation from explanted DRG	N/A	(23) Pope C, Kim SK, Marzo A et al. Organ- specific regulation of the CD8 T cell response to Listeria monocytogenes infection. Journal of immunology, 166(5), 3402-3409 (2001).
	VC2 (mutations in gK and UL20)	Intramuscular	Preclinical trial	HSV-1 and HSV-2	Fully protects against lethal intravaginal HSV challenge Presents cross-protective humoral and cellular immunity Absence of viral DNA in ganglionic tissues	N/A	(24) Gebhardt T, Whitney PG, Zaid A et al. Different patterns of peripheral migration by memory CD4+ and CD8+ T cells. Nature, 477(7363), 216-219 (2011).
		Intramuscular	Preclinical trial	HSV-2	Decreases acute viral replication in vagina, amount of virus in neural tissue, subsequent recurrent disease, and viral shedding Delivers protection after 6 months	Applying the criteria used for human trials	(25) Nelson MH, Bird MD, Chu CF et al. Rapid clearance of herpes simplex virus type 2 by CD8+ T cells requires high level expression of effector T cell functions. J Reprod Immunol, 89(1), 10-17 (2011).
	HSV-2 ICP0-∆NLS)	Footpad injection	Preclinical trial	HSV-2	Significantly reduces viral shedding in vagina No detectable infection	N/A	(26) Bertke AS, Patel A, Imai Y, Apakupakul K, Margolis TP, Krause PR. Latency-associated transcript (LAT) exon 1 controls herpes simplex virus species-specific phenotypes: reactivation in the guinea pig genital model and neuron subtype-specific latent expression of LAT. J Virol, 83(19), 10007-10015 (2009).
	HSV-2 gE deletion	Intramuscular, intravaginal, and intravenous	Preclinical trial	HSV-2	No disease mortality Absence of infectious virus in DRG and recurrent HSV shedding in vagina Decreases recurrent genital HSV lesions Gives better efficacy through intramuscular route than subcutaneous route	Provides incomplete protection	(27) Schiffer JT, Corey L. Rapid host immune response and viral dynamics in herpes simplex virus-2 infection. Nat Med, 19(3), 280-290 (2013).
	VC2 (gKD31-68 deletion of HSV-1)	Intramuscular	Preclinical trial	HSV-2	Shows poor HSV replication at the immunization site Rarely infects neural tissue Lack of any genital disease Reduces severity of acute and recurrent HSV-2 shedding in vagina and quantity of virus in DRG Better selection as a prophylactic vaccine	Not effective as a therapeutic vaccine	(28) Tang VA, Rosenthal KL. Intravaginal infection with herpes simplex virus type-2 (HSV-2) generates a functional effector memory T cell population that persists in the murine genital tract. J Reprod Immunol, 87(1-2), 39-44 (2010).
		Intramuscular	Preclinical trial	HSV-1	Gives protection against HSV-1- induced ocular pathogenesis Provides complete recovery from initial conjunctivitis Increases neutralizing antibody titers along with CD3+, CD4+ and CD8+ T-cells Decreases infiltration of Iba1+ macrophages	N/A	(29) van Lint A, Ayers M, Brooks AG, Coles RM, Heath WR, Carbone FR. Herpes simplex virus specific CD8+ T cells can clear established lytic infections from skin and nerves and can partially limit the early spread of virus after cutaneous inoculation. J Immunol, 172(1), 392-397 (2004).
	R2 (HSV-1 mutation in region 2 of pUL37)	Intramuscular, intradermal, and intravaginal	Preclinical trial	HSV-2	Increases neutralizing antibodies Decreases acute and recurrent HSV latent virus detection in DRG and recurrent shedding Rarely infects neural tissue Shows more effectivity via intradermal route	N/A	(30) Rott LS, Briskin MJ, Andrew DP, Berg EL, Butcher EC. A fundamental subdivision of circulating lymphocytes defined by adhesion to mucosal addressin cell adhesion molecule 1. Comparison with vascular cell adhesion molecule-1 and correlation with beta 7 integrins and memory differentiation. J Immunol, 156(10), 3727-3736 (1996).
	HSV-1 ICP0∆NLS	Subcutaneous and intramuscular	Preclinical trial	HSV-1	Shows less infectious virus during acute infection in TG and brainstem Stimulates an immune response by increasing the gB-elicited interferon (IFN)- γ, granzyme B and CD107a; and decreasing LAG-3, PD-1, and TIM-3 Gives protection against ocular HSV-1 challenge by reducing ocular neovascularization and suppressing peripheral nerve virus replication	T-cell response is only observed at a single time point	(31) Mebius RE, Streeter PR, Michie S, Butcher EC, Weissman IL. A developmental switch in lymphocyte homing receptor and endothelial vascular addressin expression regulates lymphocyte homing and permits CD4+ CD3- cells to colonize lymph nodes. Proc Natl Acad Sci U S A, 93(20), 11019-11024 (1996).
Naked DNA vaccine	pSVL- HSV-1 gD, pRc/CMV- HSV-1 gD	Intramuscular	Preclinical trial	HSV-1	Reduces serum anti-gD antibody, anti-HSV1 neutralizing antibody and anti-gD ELISA responses Gives non- specific changes in ELISA and neutralization antibody titers	Provides low protection against HSV-1 Not a useful alternative of a gD subunit vaccine	(32) Mackay CR, Andrew DP, Briskin M, Ringler DJ, Butcher EC. Phenotype, and migration properties of three major subsets of tissue homing T cells in sheep. Eur J Immunol, 26(10), 2433-2439 (1996).
	pDNA encoding HSV-2 gD2	Intramuscular	Clinicaltrial	HSV-1-/HSV-2-, HSV-1+/HSV-2-	Provides safe and well tolerated with no dose-limiting toxicities Increases D2-specific cytotoxic T- cell and lymphoproliferati on immune responses	Produces adverse events that are mostly local site reactions	(33) Abitorabi MA, Mackay CR, Jerome EH, Osorio O, Butcher EC, Erle DJ. Differential expression of homing molecules on recirculating lymphocytes from sheep gut, peripheral, and lung lymph. J Immunol, 156(9), 3111-3117 (1996).
	pDNAs encoding HSV-2 gD2	Subcutaneous	Preclinical trial	HSV-2	Provides fully protection against lethal intravaginal HSV-2 infection Produces strong HSV-2 virion- specific IgG and neutralizing antibody responses Reduces all levels of recurrent HSV-2 significantly Reduces acute and recurrent disease, recurrent lesion days and latent HSV-2 load	Should be studied in a greater number of guinea pigs	(34) von Andrian UH, Mackay CR. T-cell function and migration. Two sides of the same coin. N Engl J Med, 343(14), 1020-1034 (2000).
	pDNA encoding HSV-2 gD2 coupled with Vaxfectin ®	Intramuscular	Preclinical trial	HSV-2	Increases IgG antibody titers Provides protection against lethal HSV-2 challenge Reduces vaginal HSV load and viral latency in DRG	Limited sensitivity for IgG assay	(35) Mackay LK, Wakim L, van Vliet CJ et al. Maintenance of T cell function in the face of chronic antigen stimulation and repeated reactivation for a latent virus infection. J Immunol, 188(5), 2173-2178 (2012).
	pDNA encoding HSV-2 gD2 and UL46 and UL47 genes coupled with Vaxfectin ®	Intramuscular	Preclinical trial	HSV-2	Reduces viral replication and shedding in genital tract, latent HSV-2 DNA in DRG, and frequency of recurrent disease Completely protects from both primary and recurrent genital disease	Includes additional controls including irrelevant plasmids coupled with Vaxfectin®	(35) Mackay LK, Wakim L, van Vliet CJ et al. Maintenance of T Cell Function in the Face of Chronic Antigen Stimulation and Repeated Reactivation for a Latent Virus Infection. J Immunol, (2012).
	Codon-modified polynucleo-tide vaccine	Intradermal in forearm	Clinical trial	HSV-2	Provides safe and well tolerated protection with no moderate or serious adverse effects Increases immune cellular activity	Minimal antibodies increase with overall no statistical significance Insufficient number of subjects to determine a significant placebo effect	(36) Mackay LK, Stock AT, Ma JZ et al. Long-lived epithelial immunity by tissue-resident memory T (TRM) cells in the absence of persisting local antigen presentation. Proc Natl Acad Sci U S A, 109(18), 7037-7042 (2012)
	COR-1: (1) Full-length HSV-2 envelope gD2 and (2) truncated version of gD2 fused to a ubiquitin sequence				Presence of CD45+, CD4+, CD68+ macrophages and polymorphonucle ar neutrophils at site of immunization Decreases mean number of outbreaks and viral shedding
	SLV-20: (1) pGX27 with tissue plasmino- gen activator (tpa), Flt3L and HSV-2 gB and UL39, (2) pGX27 with gD2, ICP0 and ICP4 and (3) pGX27 with IL-12- IL-21 and MIP-1α	Intramuscular	Preclinical trial	HSV-2	Inhibits pathological progression after viral infection Increases survival rate Reduces virus titer and viral shedding Increases IFN- γ, CD4+, CD8+ and CD44hiCD62Lhi central memory T-cells expression	Does not show any significant differences in immunoglobulin IgA, IgM, IgG1 and IgG3 levels	(37) Masopust D, Picker LJ. Hidden memories: frontline memory T cells and early pathogen interception. J Immunol, 188(12), 5811-5817 (2012).
Protein- based subunit vaccine	HSV-2 gD2t with 3-O-deacylated mono- phosphoryl	Intramuscular	Preclinical trial	HSV-1	Reduces latent viral load significantly Provides protection against acute and recurrent HSV-2 infection	Not as effective as replication- defective dl5-29	(38) Suni MA, Ghanekar SA, Houck DW et al. CD4(+) CD8(dim) T lymphocytes exhibit enhanced cytokine expression, proliferation, and cytotoxic activity in response to HCMV and HIV-1 antigens. Eur J Immunol, 31(8), 2512-2520 (2001).
	lipid A (MPL)- aluminum hydroxide (alum)	Subcutaneous	Preclinical trial	HSV-2	Provides protection against acute and recurrent HSV infection and acute viral shedding Reduces recurrent lesion days; sufficient to prevent most recurrent lesion episodes significantly	Does not show significant reduction in the mean number of days with recurrent diseases Not sufficient to suppress early stages of viral reactivation Produces low levels of HSV-2 virion-specific antibodies	(34) von Andrian UH, Mackay CR. T-cell function and migration. Two sides of the same coin. N Engl J Med, 343(14), 1020-1034 (2000).
	HSV-2 gD with MPL- alum	Intramuscular	Clinical trial	HSV-1-/HSV-2-, HSV-1±/HSV-2±	Presents a protective effect in those women who were HSV-1 and HSV-2 seronegative	Ineffective in women who are seropositive for HSV-1 but seronegative for HSV-2 Ineffective in men regardless of serologic status	(39) Jiang X, Chentoufi AA, Hsiang C et al. The herpes simplex virus type 1 latency associated transcript (LAT) can protect neuronal derived C1300 and Neuro2A cells from Granzyme B induced apoptosis and CD8 T-cell killing. J Virol, (2010).
		Subcutaneous	Preclinical trial	HSV- 1 and HSV- 2	Gives almost complete protection against primary infection Presents better protection against latent infection	Does not prevent mucosal infection	(40)
	HSV-2 gD and gB adjuvanted with a novel T- cell antigen and tegument protein UL40	Intramuscular	Preclinical trial	HSV-2	Increases HSV-2 antigen-specific CD8+ T- cell responses Stimulates high titers of neutralizing antibodies Reduces HSV shedding in vagina, lesion scores and latent infection	N/A	(41) Jameson SC, Masopust D. Diversity in T cell memory: an embarrassment of riches. Immunity, 31(6), 859-871 (2009).
	HSV-2 gD2 and gB2 formulated in a nano- emulsion adjuvant (NE01- gD2/gB2)	Intranasal and intramuscular	Preclinical trial	HSV-2	Increases neutralizing antibodies levels Reduces acute and recurrent disease scores and shedding of virus Reduces detection of latent virus in DRG	Less efficiently induces neutralizing antibodies than intramuscular IgD2 with MPL- alum vaccine	(42) Khan AA, Srivastava R, Spencer D et al. Phenotypic and Functional Characterization of Herpes Simplex Virus Glycoprotein B Epitope-specific Effector and Memory CD8+ T Cells from Ocular Herpes Symptomatic and Asymptomatic Individuals. Journal of virology, (2015).
	Trivalent (gC2, gD2, gE2) subunit vaccine mixed with CpG and alum	Intramuscular	Preclinical trial	HSV-2	Produces antibodies that binds to gC2 and blocks its ability to bind C3b for immune evasion	gC2 are not immunogenic Without adjuvant during natural HSV-2 infection in humans or HSV-2 infected guinea pigs	(43) Shin H, Iwasaki A. A vaccine strategy that protects against genital herpes by establishing local memory T cells. Nature, 491(7424), 463-467 (2012).
		Intramuscular	Preclinical trial	HSV-1 and HSV-2	Increases HSV glycoprotein- specific antibodies which neutralizes HSV-1 and HSV-2 Provides remarkable durability of vaccine response (continues up to 21 months post- immunization) Exhibits little to no viral replication Absence of viral DNA in brains or trigeminal ganglia Provides protection against nHSV (maternal immunization promotes transfer of neutralizing antibodies and protects offspring from disseminated disease, weight loss, anxiety-like behaviour, and mortality)	N/A	(44) Khan AA, Srivastava R, Chentoufi AA et al. Bolstering the Number and Function of HSV-1-Specific CD8(+) Effector Memory T Cells and Tissue-Resident Memory T Cells in Latently Infected Trigeminal Ganglia Reduces Recurrent Ocular Herpes Infection and Disease. J Immunol, 199(1), 186-203 (2017).