Efficacy of a T Cell-Biased Adenovirus Vector as a Zika Virus Vaccine.
ABSTRACT: Zika virus (ZIKV) is a major public health concern due to the risk of congenital Zika syndrome in developing fetuses and Guillain-Barre syndrome in adults. Currently, there are no approved vaccines available to protect against infection. Adenoviruses are safe and highly immunogenic vaccine vectors capable of inducing lasting humoral and cellular immune responses. Here, we developed two Adenovirus (Ad) vectored Zika virus vaccines by inserting a ZIKV prM-E gene expression cassette into human Ad types 4 (Ad4-prM-E) and 5 (Ad5-prM-E). Immune correlates indicate that Ad5-prM-E vaccination induces both an anti-ZIKV antibody and T-cell responses whereas Ad4-prM-E vaccination only induces a T-cell response. In a highly lethal challenge in an interferon α/β receptor knockout mice, 80% of Ad5 vaccinated animals and 33% of Ad4 vaccinated animals survived a lethal ZIKV challenge, whereas no animals in the sham vaccinated group survived. In an infection model utilizing immunocompetent C57BL/6 mice that were immunized and then treated with a blocking anti-IFNAR-1 antibody immediately before ZIKV challenge, 100% of Ad4-prM-E and Ad5-prM-E vaccinated mice survived. This indicates that Ad4-prM-E vaccination is protective without the development of detectable anti-ZIKV antibodies. The protection seen in these highly lethal mouse models demonstrate the efficacy of Ad vectored vaccines for use against ZIKV.
Project description:The development of a safe and efficacious Zika virus (ZIKV) vaccine remains a global health priority. In our previous work, we developed an Adenovirus vectored ZIKV vaccine using a low-seroprevalent human Adenovirus type 4 (Ad4-prM-E) and compared it to an Ad5 vector (Ad5-prM-E). We found that vaccination with Ad4-prM-E leads to the development of a strong anti-ZIKV T-cell response without eliciting significant anti-ZIKV antibodies, while vaccination with Ad5-prM-E leads to the development of both anti-ZIKV antibody and T-cell responses in C57BL/6 mice. However, both vectors conferred protection against ZIKV infection in a lethal challenge model. Here we continued to characterize the T-cell biased immune response observed in Ad4 immunized mice. Vaccination of BALB/c mice resulted in immune correlates similar to C57BL/6 mice, confirming that this response is not mouse strain-specific. Vaccination with an Ad4 expressing an influenza hemagglutinin (HA) protein resulted in anti-HA T-cell responses without the development of significant anti-HA antibodies, indicating this unique response is specific to the Ad4 serotype rather than the transgene expressed. Co-administration of a UV inactivated Ad4 vector with the Ad5-prM-E vaccine led to a significant reduction in anti-ZIKV antibody development suggesting that this serotype-specific immune profile is capsid-dependent. These results highlight the serotype-specific immune profiles elicited by different Adenovirus vector types and emphasize the importance of continued characterization of these alternative Ad serotypes.
Project description:Zika virus (ZIKV) emerged on a global scale and no licensed vaccine ensures long-lasting anti-ZIKV immunity. Here we report the design and comparative evaluation of four replication-deficient chimpanzee adenoviral (ChAdOx1) ZIKV vaccine candidates comprising the addition or deletion of precursor membrane (prM) and envelope, with or without its transmembrane domain (TM). A single, non-adjuvanted vaccination of ChAdOx1 ZIKV vaccines elicits suitable levels of protective responses in mice challenged with ZIKV. ChAdOx1 prME ?TM encoding prM and envelope without TM provides 100% protection, as well as long-lasting anti-envelope immune responses and no evidence of in vitro antibody-dependent enhancement to dengue virus. Deletion of prM and addition of TM reduces protective efficacy and yields lower anti-envelope responses. Our finding that immunity against ZIKV can be enhanced by modulating antigen membrane anchoring highlights important parameters in the design of viral vectored ZIKV vaccines to support further clinical assessments.
Project description:<h4>Background</h4>Induction of potent long lasting effector T cell responses against liver stage malaria antigens strongly correlates with protection from malaria. While Adenovirus serotype 5 (Ad5) based malaria vaccine platforms have the ability to induce potent effector T cell responses against transgenes, high rates of pre-existing Ad5 immunity in malaria endemic regions has prompted study of alternative Ad serotype based malaria vaccines as replacements for Ad5 based malaria vaccines. The research described in this article examines the utility of alternative serotype adenovirus serotype 4 (Ad4) expressing a sporozoite surface protein (circumsporozoite protein (CSP)) (Ad4-CSP) to induce immune responses against CSP. The immunogenicity of Ad4-CSP was also tested in homologous and heterologous prime boost vaccinations in both Ad5 naïve and Ad5 immune backgrounds as compared to use of Ad5-CSP.<h4>Results</h4>In Ad5 naïve animals, use of Ad4-CSP priming vaccinations followed by boosting with Ad5-CSP (Ad4-CSP/Ad5-CSP) maximally increased the numbers of CSP specific cytokine secreting cytotoxic T cells relative to repeated use of Ad5-CSP. The Ad4-CSP/Ad5-CSP regimen also induced equivalent levels of CSP specific cell killing as did homologous prime-boost vaccinations with Ad5-CSP, despite stimulating lower numbers of CSP specific cytotoxic T cells. Priming with Ad4-CSP followed by a homologous boost resulted in significantly less CSP specific humoral responses than any other vaccination regimen tested in Ad naïve animals. In Ad5 immune animals, addition of Ad4-CSP in homologous or heterologous prime boost resulted in inductions of higher CSP specific responses than animals repeatedly vaccinated with Ad5-CSP alone. However, the observed responses were well below those observed in similarly treated Ad naïve mice.<h4>Conclusions</h4>While the Ad4-CSP/Ad5-CSP and Ad5-CSP/Ad5-CSP vaccination regimens resulted in equivalent CSP specific killing in Ad naïve animals, Ad4-CSP/Ad5-CSP achieved this result with a lower percentage of CSP specific CD8+ T cells and a higher number of IFN? secreting cells, suggesting that the Ad4-CSP/Ad5-CSP vaccination regimen elicits more efficient cytotoxic T cells. In Ad5 immune animals use of Ad4-CSP improved CSP specific immune responses as compared to repeated use of Ad5-CSP, but could not achieve the levels of immunogenicity observed when the same vaccine regimens were used in Ad naïve animals. These data indicate the existence of some level of immunological cross-reactivity between these two adenovirus subgroups. Based on these results, it is suggested that future studies should undertake similarly stringent analyses of alternative Ad serotypes to establish their effectiveness as replacements for Ad5.
Project description:Since it emerged in Brazil in May 2015, the mosquito-borne Zika virus (ZIKV) has raised global concern due to its association with a significant rise in the number of infants born with microcephaly and neurological disorders such as Guillain-Barré syndrome. We developed prototype subunit and adenoviral-based Zika vaccines encoding the extracellular portion of the ZIKV envelope gene (E) fused to the T4 fibritin foldon trimerization domain (Efl). The subunit vaccine was delivered intradermally through carboxymethyl cellulose microneedle array (MNA). The immunogenicity of these two vaccines, named Ad5.ZIKV-Efl and ZIKV-rEfl, was tested in C57BL/6 mice. Prime/boost immunization regimen was associated with induction of a ZIKV-specific antibody response, which provided neutralizing immunity. Moreover, protection was evaluated in seven-day-old pups after virulent ZIKV intraperitoneal challenge. Pups born to mice immunized with Ad5.ZIKV-Efl were all protected against lethal challenge infection without weight loss or neurological signs, while pups born to dams immunized with MNA-ZIKV-rEfl were partially protected (50%). No protection was seen in pups born to phosphate buffered saline-immunized mice. This study illustrates the preliminary efficacy of the E ZIKV antigen vaccination in controlling ZIKV infectivity, providing a promising candidate vaccine and antigen format for the prevention of Zika virus disease.
Project description:Current efforts to develop Zika virus (ZIKV) subunit vaccines have been focused on pre-membrane (prM) and envelope (E) proteins, but the role of NS1 in ZIKV-specific immune response and protection is poorly understood. Here, we develop an attenuated recombinant vesicular stomatitis virus (rVSV)-based vaccine expressing ZIKV prM-E-NS1 as a polyprotein. This vectored vaccine candidate is attenuated in mice, where a single immunization induces ZIKV-specific antibody and T cell immune responses that provide protection against ZIKV challenge. Co-expression of prM, E, and NS1 induces significantly higher levels of Th2 and Th17 cytokine responses than prM-E. In addition, NS1 alone is capable of conferring partial protection against ZIKV infection in mice even though it does not induce neutralizing antibodies. These results demonstrate that attenuated rVSV co-expressing prM, E, and NS1 is a promising vaccine candidate for protection against ZIKV infection and highlights an important role for NS1 in ZIKV-specific cellular immune responses.
Project description:The impact of the Zika virus (ZIKV) epidemic highlights the need for vaccines that reduce or prevent infection and reliably prevent teratogenic complications. The live-attenuated measles virus (MV) vaccine strains are a promising vaccine platform, since they induce robust humoral and cellular immune responses against additional antigens and have an excellent safety record. To explore its potential to protect against ZIKV, we compared a recombinant Schwarz strain MV that encodes ZIKV prM and soluble E proteins (MV-Zika-sE) with a prototypic alum-adjuvanted whole inactivated ZIKV particle vaccine. Analysis of MV-Zika-sE-infected cells confirmed antigen expression, and the virus replicated with vaccine strain characteristics. Immunized IFNAR-/--CD46Ge mice developed E protein-specific and neutralizing antibodies, and ZIKV E-specific cellular immune responses were observed by gamma interferon (IFN-?) enzyme-linked immunospot (ELISpot) and in vitro T cell proliferation assays. To analyze protective efficacy, vaccinated female mice were challenged with ZIKV after allogeneic mating. In MV-Zika-sE-vaccinated mice, weight gain was similar to that in uninfected mice, while no plasma viremia was detectable in the majority of the animals. In contrast, infected control animals gained less weight and experienced about 100-fold higher viremia over at least 3?days. Moreover, vaccination with MV-Zika-sE reduced the ZIKV load in different organs and the placentas and prevented infection of the fetus. Consequently, no fetal growth retardation, anemia, or death due to ZIKV infection was seen in MV-Zika-sE-vaccinated dams. In contrast, the inactivated ZIKV vaccine had little to no effect in our studies. Therefore, the MV-derived ZIKV vaccine is a promising candidate for further preclinical and clinical development.IMPORTANCE Zika virus (ZIKV) is a mosquito-borne flavivirus that causes a variety of neurological complications, including congenital birth defects. Despite the urgent need, no ZIKV vaccine has yet been licensed. Recombinant vaccine strain-derived measles viruses (MV) constitute a promising vector platform to induce immunity against foreign pathogens by expressing antigens from additional transcription units while at the same time possessing a remarkable safety profile. This concept has already been validated against different pathogens, including at least 3 other flaviviruses, and our data show that vaccination with MV expressing soluble ZIKV E protein significantly diminishes infection and prevents fetal loss or damage in an allogeneic mouse pregnancy model. It can thus be regarded as a promising emergency vaccine candidate with the potential for inclusion in routine vaccination settings in areas of endemicity to prevent teratogenic effects of circulating ZIKV during pregnancy, comparable to standard rubella virus vaccination.
Project description:Current design of Zika virus (ZIKV) vaccine mainly considered envelope (E) as the major target antigen. Non-structural protein NS1 was seldom considered. Herein, we generated three adenovirus-vectored vaccines carrying E (Ad2-E), or premembrane/membrane (prM/M) with E (Ad2-prME), or NS1 in addition to prM/M with E (Ad2-prME-NS1). Ad2-prME induced higher neutralizing antibody response to ZIKV than Ad2-E, suggesting prM/M is important for the folding of immunogenic E. Most intriguingly, Ad2-prME-NS1 elicited the best viral inhibition when the immune sera were added to ZIKV-infected cells. In ZIKV-challenged neonatal mice born to maternally immunized dams, Ad2-prME-NS1 conferred the best protection in preventing weight loss, neurological disorders, and viral replication. Ad2-prME also conferred significant protection but was less effective than Ad2-prME-NS1, whereas Ad2-E only alleviated neurological symptoms but did not inhibit viral replication. Our study suggested that NS1 should be considered in the design of ZIKV vaccine in addition to prM/M and E.
Project description:The human cytomegalovirus (HCMV) virion envelope protein glycoprotein B (gB) is essential for viral entry and represents a major target for humoral responses following infection. Previously, a phase 2 placebo-controlled clinical trial conducted in solid organ transplant candidates demonstrated that vaccination with gB plus MF59 adjuvant significantly increased gB enzyme-linked immunosorbent assay (ELISA) antibody levels whose titer correlated directly with protection against posttransplant viremia. The aim of the current study was to investigate in more detail this protective humoral response in vaccinated seropositive transplant recipients. We focused on 4 key antigenic domains (AD) of gB (AD1, AD2, AD4, and AD5), measuring antibody levels in patient sera and correlating these with posttransplant HCMV viremia. Vaccination of seropositive patients significantly boosted preexisting antibody levels against the immunodominant region AD1 as well as against AD2, AD4, and AD5. A decreased incidence of viremia correlated with higher antibody levels against AD2 but not with antibody levels against the other 3 ADs. Overall, these data support the hypothesis that antibodies against AD2 are a major component of the immune protection of seropositives seen following vaccination with gB/MF59 vaccine and identify a correlate of protective immunity in allograft patients.
Project description:Novel vaccination approaches against foot-and-mouth disease (FMD) include the use of replication-defective human adenovirus type 5 (Ad5) vectors that contain the capsid-encoding regions of FMD virus (FMDV). Ad5 containing serotype A24 capsid sequences (Ad5.A24) has proved to be effective as a vaccine against FMD in livestock species. However, Ad5-vectored FMDV serotype O1 Campos vaccine (Ad5.O1C.2B) provides only partial protection of cattle against homologous challenge. It has been reported that a fiber-modified Ad5 vector expressing Arg-Gly-Asp (RGD) enhances transduction of antigen-presenting cells (APC) in mice. In the current study, we assessed the efficacy of a fiber-modified Ad5 (Adt.O1C.2B.RGD) in cattle. Expression of FMDV capsid proteins was superior in cultured cells infected with the RGD-modified vector. Furthermore, transgene expression of Adt.O1C.2B.RGD was enhanced in cell lines that constitutively express integrin ?v?6, a known receptor for FMDV. In contrast, capsid expression in cattle-derived enriched APC populations was not enhanced by infection with this vector. Our data showed that vaccination with the two vectors yielded similar levels of protection against FMD in cattle. Although none of the vaccinated animals had detectable viremia, FMDV RNA was detected in serum samples from animals with clinical signs. Interestingly, CD4(+) and CD8(+) gamma interferon (IFN-?)(+) cell responses were detected at significantly higher levels in animals vaccinated with Adt.O1C.2B.RGD than in animals vaccinated with Ad5.O1C.2B. Our results suggest that inclusion of an RGD motif in the fiber of Ad5-vectored FMD vaccine improves transgene delivery and cell-mediated immunity but does not significantly enhance vaccine performance in cattle.
Project description:Zika virus (ZIKV) has spread in many countries or territories causing severe neurologic complications with potential fatal outcomes. The small primate common marmosets are susceptible to ZIKV, mimicking key features of human infection. Here, a novel simian adenovirus type 23 vector-based vaccine expressing ZIKV pre-membrane-envelope proteins (Sad23L-prM-E) was produced in high infectious titer. Due to determination of immunogenicity in mice, a single-dose of 3×108 PFU Sad23L-prM-E vaccine was intramuscularly inoculated to marmosets. This vaccine raised antibody titers of 104.07 E-specific and 103.13 neutralizing antibody (NAb), as well as robust specific IFN-? secreting T-cell response (1,219 SFCs/106 cells) to E peptides. The vaccinated marmosets, upon challenge with a high dose of ZIKV (105 PFU) six weeks post prime immunization, reduced viremia by more than 100 folds, and the low level of detectable viral RNA (<103 copies/ml) in blood, saliva, urine and feces was promptly eliminated when the secondary NAb (titer >103.66) and T-cell response (>726 SFCs/106 PBMCs) were acquired 1-2 weeks post exposure to ZIKV, while non-vaccinated control marmosets developed long-term high titer of ZIKV (105.73 copies/ml) (P<0.05). No significant pathological lesions were observed in marmoset tissues. Sad23L-prM-E vaccine was detectable in spleen, liver and PBMCs at least 4 months post challenge. In conclusion, a prime immunization with Sad23L-prM-E vaccine was able to protect marmosets against ZIKV infection when exposed to a high dose of ZIKV. This Sad23L-prM-E vaccine is a promising vaccine candidate for prevention of ZIKV infection in humans.