Immunization of Flavivirus West Nile Recombinant Envelope Domain III Protein Induced Specific Immune Response and Protection against West Nile Virus Infection

Abstract

The domain III of the West Nile virus (WNV) envelope glycoprotein (E) was shown to serve as virus attachment domain to the cellular receptor, and neutralizing Abs have been mapped to this specific domain. In this study, domain III of the WNV E protein (WNV E DIII) was expressed as a recombinant protein and its potential as a subunit vaccine candidate was evaluated in BALB/C mice. Immunization of WNV E DIII protein with oligodeoxynucleotides (CpG-DNA) adjuvant by i.p. injection was conducted over a period of 3 wk. The immunized mice generated high titer of WNV-neutralizing Abs. Murine Ab against WNV E DIII protein was also capable of neutralizing Japanese encephalitis virus. The IgG isotypes generated were predominantly IgG2a in the murine sera against the recombinant protein. Splenocyte cultures from the mice coadministrated with WNV E DIII protein and CpG secreted large amounts of IFN-γ and IL-2 and showed proliferation of T cells in the presence of WNV E DIII protein. Overall, this study highlighted that recombinant WNV E DIII protein delivered in combination with CpG adjuvant to mice generated a Th1 immune response type against WNV and can serve as a potential vaccine to prevent WNV infection.

Type- and Subcomplex-Specific Neutralizing Antibodies against Domain III of Dengue Virus Type 2 Envelope Protein Recognize Adjacent Epitopes

“…These results suggest that the human antibody repertoire against flaviviruses may actually be directed away from these DIII neutralizing epitopes and toward the inherently less neutralizing immunodominant epitopes on DI and DII (55). Since our results suggest that strongly neutralizing antibodies against DIII of DENV-2 map to the lateral ridge and A-strand epitopes, flavivirus DIII-based vaccines (13,15,31) that intentionally skew the humoral response to these epitopes and away from the cross-reactive, poorly accessible epitope in the AB loop could elicit a greater protective response.…”

The relative contribution of antibody and CD8+ T cells to vaccine immunity against West Nile encephalitis virus

“…Plasmid based DNA vaccines induced robust helper T cell immune responses, cytokine production, and humoral immunity [21]. Vaccination with multiple doses of purified recombinant WNV E protein or domain III also elicited neutralizing antibodies and protected mice from WNV challenge [24][25][26]. However, in some of these studies, mice immunized with recombinant protein succumbed to high dose WNV challenge, suggesting that the efficacy of subunit vaccination may be limited by a failure to stimulate CD8 + T cell immunity.…”

“…Prior immunization studies with live attenuated, DNA plasmid, or protein subunit vaccines against WNV have demonstrated the induction of memory T cell responses [21,25,32], although their role in protection against challenge was not evaluated. To begin to address this question, we first assessed the efficiency of induction of WNV-specific CD8 + T cells after immunzation by analyzing intracellular IFN-γ production ex vivo after antigen-specific restimulation with D b and K b -restricted WNV NS4B and E peptides [37,38].…”

West Nile Virus Vaccination in Horses – IgM and IgG responses after injection in different muscles

“…The clinical progression of WNV infection varies greatly, with symptoms varying from subclinical (asymptomatic), to a mild flu-like disease (West Nile Fever), to a severe form involving neurological symptoms with considerable mortality (Weese et al 2003). The important complications of a WNV infection are meningo-encephalitis and other neurological symptoms such as acute paralysis or paresis (Weese et al 2003, Chu et al 2007). The severity of the disease is influenced by the age and physical condition of the host and by the specific virulence of the virus strain involved.…”