Study On DNA Vaccine Of Herpes Simplex Virus Type Ⅱ

Herpes simplex virus type2(HSV-2) is a sexually transmitted pathogen thatmore than500million people in the worldwide have been infected for now.Meanwhile, HSV-2can induce genital herpes and cervical cancer, as well as increasethe risk of HIV-1infection. HSV-2is a neurotropic virus that cause a variety ofinfections and establish longlife latency in sensory neurons and lumbosacral dorsalroot ganglion of the host. Antiviral drugs used in clinical treatment, such as acyclovir,can reduce disease severity, but they can not prevent viral recovery and transmissionin patients. So the development of safe and effective HSV-2vaccines have been thepriority to prevent viral infection. Current studies have showed that humoralimmunity can not clear HSV-2completely, while cellular immunity is more efficacyto inhibit primary and recurrent infection. Therefor, the development of HSV-2vaccines in the future should mainly focus on cellular immune responses and keepbalance with humoral immune.DNA vaccines has brought a new dawn and been widely used in human vaccineclinical trials, such as influenza, HBV, HIV, and animal experiments indicated thatHSV-2DNA vaccine can induce a balance of humoral immunity and cellularimmunity. HSV-2glycoprotein D (gD), a crucial glycoprotein for HSV-2infection,plays an extremely important role in the process of crossing the membrane for viruses.gD is a major target of T cell epitope and B cell epitope that can induce a relativelyhigh neutralizing antibodies and T cell immune responses, which has been a preferredchoice in the design of HSV-2vaccines. It has been known that an epitope-peptide,UL25, can induce the proliferation and activation of CD8+T cells, suggesting that amultivalent DNA vaccine, the fusion of truncated UL25and gD2gene, can induce astronger immune response.Since the immunogenicity of DNA vaccine is weak, IL-28B was used as anadjuvant in the design of DNA vaccine to inhibit HSV-2infection. IL-28B, includedin IFN-λs family, can prevent or limit viral infection. Previous studies havedemonstrated that IL-28used as adjuvant of HIV and H1N1DNA vaccine canenhance the adaptive cellular immune response, promote the proliferation of memory cells and significantly increase specific CTL activity in small animal models.In summary, in order to obtain a stronger humoral and cellular immune responseand develop a safe and effective vaccine against HSV-2, the gene sequence encodingHSV-2gD and UL25was codon-modified, sythesized and subcloned into pcDNA3.1respectively, designated gD2and gD2UL25. The gD2and gD2UL25plasmid weretested with IL-28B for protective efficacy against HSV-2.Mice were immunized with these plasmid DNA for three times with a two-weekintervals, and then intravaginally challenged with lethal doses of HSV-2to evaluatethe immunogenicity of these DNA vaccines and their abilities to resist HSV-2viruscompared with formaldehyde inactivated HSV-2and recombinant replication-defective adenovirus capable of expressing gD2. Meanwhile, IL-28B was assessed forits potential ability to improve adaptive immune responses as a vaccine adjuvant.The results showed that DNA vaccines could induce specific humoral andcellular immunity against HSV-2, reduce viral load in Genital tract, weakly reducelesion symptoms of disease in those mice after toxicity attack with weak immuneresponse and limited protection.gD2and gD2UL25DNA vaccine along with IL-28B could significantly inducethe specific IgG and IgG2a antibody, enhance Th1associated with theantigen-specific immune responses, promote the production of neutralizing antibodiesat a relatively low level, significantly increase the secretion of IFN-γ, enhance cellularimmune responses, reduce vaginal shedding of HSV-2and increase a higher survivalafter challenged with HSV-2compared with FI-HSV-2.All have proved that DNA vaccines have a limited ability to suppress andeliminate HSV-2infection, while IL-28B can be used as an adjuvant to significantlyenhance its ability to resist HSV-2virus. And the fusion of gD2and UL25gene caninduce a higher immune response and significantly improve the ability to reducevaginal shedding of the HSV-2, which suggested that multivalent DNA vaccine maybe more effective than the monovalent one.