Randomized, Blinded, Dose-Ranging Trial of an Ebola Virus Glycoprotein Nanoparticle Vaccine With Matrix-M Adjuvant in Healthy Adults.

BACKGROUND: Ebola virus (EBOV) epidemics pose a major public health risk. There currently is no licensed human vaccine against EBOV. The safety and immunogenicity of a recombinant EBOV glycoprotein (GP) nanoparticle vaccine formulated with or without Matrix-M adjuvant were evaluated to support vaccine development. METHODS: A phase 1, placebo-controlled, dose-escalation trial was conducted in 230 healthy adults to evaluate 4 EBOV GP antigen doses as single- or 2-dose regimens with or without adjuvant. Safety and immunogenicity were assessed through 1-year postdosing. RESULTS: All EBOV GP vaccine formulations were well tolerated. Receipt of 2 doses of EBOV GP with adjuvant showed a rapid increase in anti-EBOV GP immunoglobulin G titers with peak titers observed on Day 35 representing 498- to 754-fold increases from baseline; no evidence of an antigen dose response was observed. Serum EBOV-neutralizing and binding antibodies using wild-type Zaire EBOV (ZEBOV) or pseudovirion assays were 3- to 9-fold higher among recipients of 2-dose EBOV GP with adjuvant, compared with placebo on Day 35, which persisted through 1 year. CONCLUSIONS: Ebola virus GP vaccine with Matrix-M adjuvant is well tolerated and elicits a robust and persistent immune response. These data suggest that further development of this candidate vaccine for prevention of EBOV disease is warranted.

Intradermal Vaccination With Adjuvanted Ebola Virus Soluble Glycoprotein Subunit Vaccine by Microneedle Patches Protects Mice Against Lethal Ebola Virus Challenge.

In this study, we investigated immune responses induced by purified Ebola virus (EBOV) soluble glycoprotein (sGP) subunit vaccines via intradermal immunization with microneedle (MN) patches in comparison with intramuscular (IM) injection in mice. Our results showed that MN delivery of EBOV sGP was superior to IM injection in eliciting higher levels and longer lasting antibody responses against EBOV sGP and GP antigens. Moreover, sGP-specific immune responses induced by MN or IM immunizations were effectively augmented by formulating sGP with a saponin-based adjuvant, and they were shown to confer complete protection of mice against lethal mouse-adapted EBOV (MA-EBOV) challenge. In comparison, mice that received sGP without adjuvant by MN or IM immunizations succumbed to lethal MA-EBOV challenge. These results show that immunization with EBOV sGP subunit vaccines with adjuvant by MN patches, which have been shown to provide improved safety and thermal stability, is a promising approach to protect against EBOV infection.

A Randomized, Blinded, Controlled, Dose-Ranging Study of a Respiratory Syncytial Virus Recombinant Fusion (F) Nanoparticle Vaccine in Healthy Women of Childbearing Age.

BACKGROUND: Respiratory syncytial virus (RSV) is a leading cause of infant morbidity and mortality. A recombinant RSV fusion protein nanoparticle vaccine (RSV F vaccine) candidate for maternal immunization was tested for safety and immunogenicity in women of childbearing age. METHODS: Three hundred thirty women (18-35 years) were randomized to receive 1 or 2 doses of RSV F vaccine (60 or 90 µg) with or without aluminum phosphate adjuvant, or placebo at days 0 and 28. Safety was evaluated over 180 days; immunogenicity and RSV infection rates were evaluated over 112 days. RESULTS: All vaccine formulations were well tolerated, without vaccine-related serious adverse events. Anti-F immunoglobulin G antibodies rose 6.5-15.6-fold, with significantly higher levels in 2-dose, adjuvanted regimens at day 56. Palivizumab-competitive antibody levels were undetectable at day 0 but increased up to 325 µg/mL at day 56. A 2.7- and 3.5-fold rise in RSV/A and RSV/B microneutralization antibodies were noted at day 56. Between days 56 and 112, 21% (12/56) of placebo recipients and 11% of vaccinees (26/244) showed evidence of a recent RSV infection (P = .04). CONCLUSIONS: The vaccine appeared safe, immunogenic, and reduced RSV infections. Further development as a vaccine for use in maternal immunization is warranted. CLINICAL TRIALS REGISTRATION: NCT01704365.

Maternal immunization with RSV fusion glycoprotein vaccine and substantial protection of neonatal baboons against respiratory syncytial virus pulmonary challenge.

Globally, human respiratory syncytial virus (RSV) is a major cause of severe lower respiratory infection in infants and young children. There are no licensed vaccines despite the high worldwide disease burden. RSV fusion (F) glycoprotein vaccine is the most advanced candidate for maternal immunization. In this report, a baboon maternal immunization model was used to assess the immunogenicity and protection of infants against pulmonary challenge with human RSV/A. Vaccination in the third trimester produced high anti-RSV F IgG titers and virus-neutralizing antibodies. Infants born to immunized females had high levels of serum RSV antibodies that were comparable to maternal levels at birth and persisted for over 50 days with a half-life of 14-24 days. Furthermore, infants from immunized females and challenged with RSV/A were healthy, developed less severe disease, and had only mild pulmonary inflammatory changes whereas infants born to non-vaccinated females developed more severe disease with marked to moderate interstitial pneumonia, pulmonary edema, and bronchiolar obstruction. These results support the further development of the RSV F vaccine for maternal immunization.

Use of a patch containing heat-labile toxin from Escherichia coli against travellers' diarrhoea: a phase II, randomised, double-blind, placebo-controlled field trial.

BACKGROUND: Enterotoxigenic Escherichia coli (ETEC) is a major cause of travellers' diarrhoea. We investigated the rate of diarrhoea attacks, safety, and feasibility of a vaccine containing heat-labile enterotoxin (LT) from ETEC delivered to the skin by patch in travellers to Mexico and Guatemala. METHODS: In this phase II study, healthy adults (aged 18-64 years) who planned to travel to Mexico or Guatemala and had access to a US regional vaccination centre were eligible. A centralised randomisation code was used for allocation, which was masked to participants and site staff. Primary endpoints were to investigate the field rate of ETEC diarrhoea, and to assess the safety of heat-labile toxins from E coli (LT) delivered via patch. Secondary endpoints included vaccine efficacy against travellers' diarrhoea and ETEC. Participants were vaccinated before travel, with two patches given 2-3 weeks apart. Patches contained either 37.5 mug of LT or placebo. Participants tracked stool output on diary cards in country and provided samples for pathogen identification if diarrhoea occurred. Diarrhoea was graded by the number of loose stools in 24 h: mild (three), moderate (four or five), and severe (at least six). Analysis was per protocol. The trial is registered with ClinicalTrials.gov, number NCT00516659. FINDINGS: Recruitment closed after 201 participants were assigned patches. 178 individuals received two vaccinations and travelled and 170 were analysed. 24 (22%) of 111 placebo recipients had diarrhoea, of whom 11 (10%) had ETEC diarrhoea. The vaccine was safe and immunogenic. The 59 LT-patch recipients were protected against moderate-to-severe diarrhoea (protective efficacy [PE] 75%, p=0.0070) and severe diarrhoea (PE 84%, p=0.0332). LT-patch recipients who became ill had shorter episodes of diarrhoea (0.5 days vs 2.1 days, p=0.0006) with fewer loose stools (3.7 vs 10.5, p<0.0001) than placebo. INTERPRETATION: Travellers' diarrhoea is a common ailment, with ETEC diarrhoea illness occurring in 10% of cases. The vaccine patch is safe and feasible, with benefits to the rate and severity of travellers' diarrhoea.

Structure basis of neutralization by a novel site II/IV antibody against respiratory syncytial virus fusion protein.

Globally, human respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections in newborns, young children, and the elderly for which there is no vaccine. The RSV fusion (F) glycoprotein is a major target for vaccine development. Here, we describe a novel monoclonal antibody (designated as R4.C6) that recognizes both pre-fusion and post-fusion RSV F, and binds with nanomole affinity to a unique neutralizing site comprised of antigenic sites II and IV on the globular head. A 3.9 Å-resolution structure of RSV F-R4.C6 Fab complex was obtained by single particle cryo-electron microscopy and 3D reconstruction. The structure unraveled detailed interactions of R4.C6 with antigenic site II on one protomer and site IV on a neighboring protomer of post-fusion RSV F protein. These findings significantly further our understanding of the antigenic complexity of the F protein and provide new insights into RSV vaccine design.

Intradermal immunization by Ebola virus GP subunit vaccines using microneedle patches protects mice against lethal EBOV challenge.

Development of a safe and efficacious filovirus vaccine is of high importance to public health. In this study, we compared immune responses induced by Ebola virus (EBOV) glycoprotein (GP) subunit vaccines via intradermal immunization with microneedle (MN) patches and the conventional intramuscular (IM) injection in mice, which showed that MN delivery of GP induced higher levels and longer lasting antibody responses against GP than IM injection. Further, we found that EBOV GP in formulation with a saponin-based adjuvant, Matrix-M, can be efficiently loaded onto MN patches. Co-delivery of Matrix-M with GP significantly enhanced induction of antibody responses by MN delivery, as also observed for IM injection. Results from challenge studies showed that all mice that received the GP/adjuvant formulation by MN or IM immunizations were protected from lethal EBOV challenge. Further, 4 out of 5 mice vaccinated by MN delivery of unadjuvanted GP also survived the challenge, whereas only 1 out of 5 mice vaccinated by IM injection of unadjuvanted GP survived the challenge. These results demonstrate that MN patch delivery of EBOV GP subunit vaccines, which is expected to enable improved safety and thermal stability, can confer effective protection against EBOV infection that is superior to IM vaccination.

Novel hemagglutinin nanoparticle influenza vaccine with Matrix-M™ adjuvant induces hemagglutination inhibition, neutralizing, and protective responses in ferrets against homologous and drifted A(H3N2) subtypes.

Influenza viruses frequently acquire mutations undergoing antigenic drift necessitating annual evaluation of vaccine strains. Highly conserved epitopes have been identified in the hemagglutinin (HA) head and stem regions, however, current influenza vaccines induce only limited responses to these conserved sites. Here, we describe a novel seasonal recombinant HA nanoparticle influenza vaccine (NIV) formulated with a saponin-based adjuvant, Matrix-M™. NIV induced hemagglutination inhibition (HAI) and microneutralizing (MN) antibodies against a broad range of influenza A(H3N2) subtypes. In a comparison of NIV against standard-dose and high-dose inactivated influenza vaccines (IIV and IIV-HD, respectively) in ferrets NIV elicited HAI and MN responses exceeding those induced by IIV-HD against homologous A(H3N2) by 7 fold, A(H1N1) by 26 fold, and B strain viruses by 2 fold. NIV also induced MN responses against all historic A/H3N2 strains tested, spanning more than a decade of viral evolution from the 2000-2017 influenza seasons whereas IIV and IIV-HD induced HAI and MN responses were largely directed against the homologous A(H3N2), A(H1N1), and B virus strains. NIV induced superior protection compared to IIV and IIV-HD in ferrets challenged with a homologous or 10-year drifted influenza A(H3N2) strain. HAI positive and HAI negative neutralizing monoclonal antibodies derived from mice immunized with NIV were active against homologous and drifted influenza A(H3N2) strains. Taken together these observations suggest that NIV can induce responses to one or more highly conserved HA head and stem epitopes and result in highly neutralizing antibodies against both homologous and drift strains.

MERS-CoV spike nanoparticles protect mice from MERS-CoV infection.

The Middle East respiratory syndrome coronavirus (MERS-CoV) was first discovered in late 2012 and has gone on to cause over 1800 infections and 650 deaths. There are currently no approved therapeutics or vaccinations for MERS-CoV. The MERS-CoV spike (S) protein is responsible for receptor binding and virion entry to cells, is immunodominant and induces neutralizing antibodies in vivo, all of which, make the S protein an ideal target for anti-MERS-CoV vaccines. In this study, we demonstrate protection induced by vaccination with a recombinant MERS-CoV S nanoparticle vaccine and Matrix-M1 adjuvant combination in mice. The MERS-CoV S nanoparticle vaccine produced high titer anti-S neutralizing antibody and protected mice from MERS-CoV infection in vivo.

Clostridium difficile chimeric toxin receptor binding domain vaccine induced protection against different strains in active and passive challenge models.

Clostridium difficile is the number one cause of nosocomial antibiotic-associated diarrhea in developed countries. Historically, pathogenesis was attributed two homologous glucosylating toxins, toxin-A (TcdA) and toxin-B (TcdB). Over the past decade, however, highly virulent epidemic strains of C. difficile (B1/NAP1/027) have emerged and are linked to an increase in morbidity and mortality. Increased virulence is attributed to multiple factors including: increased production of A- and B-toxins; production of binary toxin (CDT); and the emergence of more toxic TcdB variants (TcdB(027)). TcdB(027) is more cytotoxicity to cells; causes greater tissue damage and toxicity in animals; and is antigenically distinct from historical TcdB (TcdB(003)). Broadly protective vaccines and therapeutic antibody strategies, therefore, may target TcdA, TcdB variants and CDT. To facilitate the generation of multivalent toxin-based C. difficile vaccines and therapeutic antibodies, we have generated fusion proteins constructed from the receptor binding domains (RBD) of TcdA, TcdB(003), TcdB(027) and CDT. Herein, we describe the development of a trivalent toxin (T-toxin) vaccine (CDTb/TcdB(003)/TcdA) and quadravalent toxin (Q-toxin) vaccine (CDTb/TcB(003)/TcdA/TcdB(027)) fusion proteins that retain the protective toxin neutralizing epitopes. Active immunization of mice or hamsters with T-toxin or Q-toxin fusion protein vaccines elicited the generation of toxin neutralizing antibodies to each of the toxins. Hamsters immunized with the Q-toxin vaccine were broadly protected against spore challenge with historical C. difficile 630 (toxinotype 0/ribotype 003) and epidemic NAP1 (toxinotype III/ribotype 027) strains. Fully human polyclonal antitoxin IgG was produced by immunization of transgenic bovine with these fusion proteins. In passive transfer studies, mice were protected against lethal toxin challenge. Hamsters treated with human antitoxin IgG were completely protected when challenged with historical or epidemic strains of C. difficile. The use of chimeric fusion proteins is an attractive approach to producing multivalent antitoxin vaccines and therapeutic polyclonal antibodies for prevention and treatment of C. difficile infections (CDI).

Neuraminidase-based recombinant virus-like particles protect against lethal avian influenza A(H5N1) virus infection in ferrets.

Avian influenza A (H5N1) viruses represent a growing threat for an influenza pandemic. The presence of widespread avian influenza virus infections further emphasizes the need for vaccine strategies for control of pre-pandemic H5N1 and other avian influenza subtypes. Influenza neuraminidase (NA) vaccines represent a potential strategy for improving vaccines against avian influenza H5N1 viruses. To evaluate a strategy for NA vaccination, we generated a recombinant influenza virus-like particle (VLP) vaccine comprised of the NA protein of A/Indonesia/05/2005 (H5N1) virus. Ferrets vaccinated with influenza N1 NA VLPs elicited high-titer serum NA-inhibition (NI) antibody titers and were protected from lethal challenge with A/Indonesia/05/2005 virus. Moreover, N1-immune ferrets shed less infectious virus than similarly challenged control animals. In contrast, ferrets administered control N2 NA VLPs were not protected against H5N1 virus challenge. These results provide support for continued development of NA-based vaccines against influenza H5N1 viruses.

Matrix-M adjuvant enhances antibody, cellular and protective immune responses of a Zaire Ebola/Makona virus glycoprotein (GP) nanoparticle vaccine in mice.

Ebola virus (EBOV) causes severe hemorrhagic fever for which there is no approved treatment or preventive vaccine. Immunological correlates of protective immunity against EBOV disease are not well understood. However, non-human primate studies have associated protection of experimental vaccines with binding and neutralizing antibodies to the EBOV glycoprotein (GP) as well as EBOV GP-specific CD4(+) and CD8(+) T cells. In this report a full length, unmodified Zaire EBOV GP gene from the 2014 EBOV Makona strain (EBOV/Mak) was cloned into a baculovirus vector. Recombinant EBOV/Mak GP was produced in Sf9 insect cells as glycosylated trimers and, when purified, formed spherical 30-40 nm particles. In mice, EBOV/Mak GP co-administered with the saponin adjuvant Matrix-M was significantly more immunogenic, as measured by virus neutralization titers and anti-EBOV/Mak GP IgG as compared to immunization with AlPO4 adjuvanted or non-adjuvanted EBOV/Mak GP. Similarly, antigen specific T cells secreting IFN-γ were induced most prominently by EBOV/Mak GP with Matrix-M. Matrix-M also enhanced the frequency of antigen-specific germinal center B cells and follicular helper T (TFH) cells in the spleen in a dose-dependent manner. Immunization with EBOV/Mak GP with Matrix-M was 100% protective in a lethal viral challenge murine model; whereas no protection was observed with the AlPO4 adjuvant and only 10% (1/10) mice were protected in the EBOV/Mak GP antigen alone group. Matrix-M adjuvanted vaccine induced a rapid onset of specific IgG and neutralizing antibodies, increased frequency of multifunctional CD4+ and CD8(+) T cells, specific TFH cells, germinal center B cells, and persistence of EBOV GP-specific plasma B cells in the bone marrow. Taken together, the addition of Matrix-M adjuvant to the EBOV/Mak GP nanoparticles enhanced both B and T-cell immune stimulation which may be critical for an Ebola subunit vaccine with broad and long lasting protective immunity.

Human polyclonal immunoglobulin G from transchromosomic bovines inhibits MERS-CoV in vivo.

As of 13 November 2015, 1618 laboratory-confirmed human cases of Middle East respiratory syndrome coronavirus (MERS-CoV) infection, including 579 deaths, had been reported to the World Health Organization. No specific preventive or therapeutic agent of proven value against MERS-CoV is currently available. Public Health England and the International Severe Acute Respiratory and Emerging Infection Consortium identified passive immunotherapy with neutralizing antibodies as a treatment approach that warrants priority study. Two experimental MERS-CoV vaccines were used to vaccinate two groups of transchromosomic (Tc) bovines that were genetically modified to produce large quantities of fully human polyclonal immunoglobulin G (IgG) antibodies. Vaccination with a clade A γ-irradiated whole killed virion vaccine (Jordan strain) or a clade B spike protein nanoparticle vaccine (Al-Hasa strain) resulted in Tc bovine sera with high enzyme-linked immunosorbent assay (ELISA) and neutralizing antibody titers in vitro. Two purified Tc bovine human IgG immunoglobulins (Tc hIgG), SAB-300 (produced after Jordan strain vaccination) and SAB-301 (produced after Al-Hasa strain vaccination), also had high ELISA and neutralizing antibody titers without antibody-dependent enhancement in vitro. SAB-301 was selected for in vivo and preclinical studies. Administration of single doses of SAB-301 12 hours before or 24 and 48 hours after MERS-CoV infection (Erasmus Medical Center 2012 strain) of Ad5-hDPP4 receptor-transduced mice rapidly resulted in viral lung titers near or below the limit of detection. Tc bovines, combined with the ability to quickly produce Tc hIgG and develop in vitro assays and animal model(s), potentially offer a platform to rapidly produce a therapeutic to prevent and/or treat MERS-CoV infection and/or other emerging infectious diseases.

Modeling maternal fetal RSV F vaccine induced antibody transfer in guinea pigs.

BACKGROUND: Protection of newborns and young infants against RSV disease via maternal immunization mediated by transplacental transfer of antibodies is under evaluation in third-trimester pregnant women with the RSV recombinant F nanoparticle vaccine (RSV F vaccine). Since the hemichorial placental architecture in guinea pigs and humans is similar, the guinea pig model was employed to assess RSV F vaccine immunogenicity in pregnant sows and to compare RSV-specific maternal antibody levels in their pups. METHODS: Thirty (30) presumptive pregnant guinea pigs were immunized on gestational day 25 and 46 with placebo (PBS), 30µg RSV F, or 30µg RSV F+400µg aluminum phosphate. Sera at delivery/birth (sows/pups) and 15 and 30 days post-partum (pups) were analyzed for the presence of anti-F IgG, palivizumab-competitive antibody (PCA) and RSV/A microneutralization (MN). RESULTS: The rates of pregnancy and stillbirth were similar between controls and vaccinees. The vaccine induced high levels of anti-F IgG, PCA and MN in sows, with the highest levels observed in adjuvanted vaccinees. Placental transfer to pups was proportional to the maternal antibody levels, with concentration effects observed for all immune measures. CONCLUSIONS: The RSV F vaccine was safe and immunogenic in pregnant guinea pigs and supported robust transplacental antibody transfer to their pups. Relative concentration of antibodies in the pups was observed even in the presence of high levels of maternal antibody. Guinea pigs may be an important safety and immunogenicity model for preclinical assessment of candidate vaccines for maternal immunization.

An insect cell derived respiratory syncytial virus (RSV) F nanoparticle vaccine induces antigenic site II antibodies and protects against RSV challenge in cotton rats by active and passive immunization.

Post-infectious immunity to respiratory syncytial virus (RSV) infection results in limited protection as evidenced by the high rate of infant hospitalization in the face of high titer, maternally derived RSV-specific antibodies. By contrast, RSV fusion (F) glycoprotein antigenic site II humanized monoclonal antibodies, palivizumab and motavizumab, have been shown to reduce RSV-related hospitalization in infants. Immunogenicity and efficacy studies were conducted in cotton rats comparing a recombinant RSV F nanoparticle vaccine with palivizumab and controlled with live RSV virus intranasal immunization and, formalin inactivated RSV vaccine. Active immunization with RSV F nanoparticle vaccine containing an alum adjuvant induced serum levels of palivizumab competing antibody (PCA) greater than passive administration of 15 mg/kg palivizumab (human prophylactic dose) in cotton rats and neutralized RSV-A and RSV-B viruses. Immunization prevented detectable RSV replication in the lungs and, unlike passive administration of palivizumab, in the nasal passage of challenged cotton rats. Histology of lung tissues following RSV challenge showed no enhanced disease in the vaccinated groups in contrast to formalin inactivated 'Lot 100' vaccine. Passive intramuscular administration of RSV F vaccine-induced immune sera one day prior to challenge of cotton rats reduced viral titers by 2 or more log10 virus per gram of lung and nasal tissue and at doses less than palivizumab. A recombinant RSV F nanoparticle vaccine protected lower and upper respiratory tract against both RSV A and B strain infection and induced polyclonal palivizumab competing antibodies similar to but potentially more broadly protective against RSV than palivizumab.

Purified coronavirus spike protein nanoparticles induce coronavirus neutralizing antibodies in mice.

Development of vaccination strategies for emerging pathogens are particularly challenging because of the sudden nature of their emergence and the long process needed for traditional vaccine development. Therefore, there is a need for development of a rapid method of vaccine development that can respond to emerging pathogens in a short time frame. The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in late 2012 demonstrate the importance of coronaviruses as emerging pathogens. The spike glycoproteins of coronaviruses reside on the surface of the virion and are responsible for virus entry. The spike glycoprotein is the major immunodominant antigen of coronaviruses and has proven to be an excellent target for vaccine designs that seek to block coronavirus entry and promote antibody targeting of infected cells. Vaccination strategies for coronaviruses have involved live attenuated virus, recombinant viruses, non-replicative virus-like particles expressing coronavirus proteins or DNA plasmids expressing coronavirus genes. None of these strategies has progressed to an approved human coronavirus vaccine in the ten years since SARS-CoV emerged. Here we describe a novel method for generating MERS-CoV and SARS-CoV full-length spike nanoparticles, which in combination with adjuvants are able to produce high titer antibodies in mice.

Immunostimulant patches containing Escherichia coli LT enhance immune responses to DNA- and recombinant protein-based Alzheimer's disease vaccines.

Immunotherapeutic approaches to treating Alzheimer's disease (AD) using vaccination strategies must overcome the obstacle of achieving adequate responses to vaccination in the elderly. Here we demonstrate for the first time that application of the Escherichia coli heat-labile enterotoxin adjuvant-laden immunostimulatory patches (LT-IS) dramatically enhances the onset and magnitude of immune responses to DNA- and protein-based vaccines for Alzheimer's disease following intradermal immunization via gene gun and conventional needles, respectively. Our studies suggest that the immune activation mediated by LT-IS offers improved potency for generating AD-specific vaccination responses that should be investigated as an adjuvant in the clinical arena.

Development of influenza H7N9 virus like particle (VLP) vaccine: homologous A/Anhui/1/2013 (H7N9) protection and heterologous A/chicken/Jalisco/CPA1/2012 (H7N3) cross-protection in vaccinated mice challenged with H7N9 virus.

The recent emergence of severe human illness caused by avian-origin influenza A(H7N9) viruses in China has precipitated a global effort to rapidly develop and test vaccine candidates. To date, non-A(H7N9) H7 subtype influenza vaccine candidates have been poorly immunogenic and difficulties in production of A(H7N9) virus seed strains have been encountered. A candidate recombinant A(H7N9) vaccine consisting of full length, unmodified hemagglutinin (HA) and neuraminidase (NA) from the A/Anhui/1/2013 and the matrix 1 (M1) protein from the A/Indonesia/05/2005 (H5N1) were cloned into a baculovirus vector. Baculovirus infected Spodoptera frugiperda (Sf9) insect cells secreted virus like particles (VLP) composed of HA, NA, and M1 that resemble mature influenza virions. Genetic construction of vaccine from acquisition of an H7N9 genomic sequence to production of A(H7N9) VLP occurred in 26 days. The immunogenicity and efficacy of A/Anhui/1/2013 (H7N9) VLP vaccine administered on days 0 and 14 were evaluated in a lethal wild-type challenge Balb/c mouse model. Control groups included a non-homologous H7 vaccine (A/chicken/Jalisco/CPA1/2012 (H7N3)-VLP), and A/Indonesia/05/2005 (H5N1)-VLP, or placebo. All vaccines were administered with or without ISCOMATRIX. A(H7N9) VLP elicited hemagglutination-inhibition (HAI) antibody titers of ≥ 1:64 against the homologous virus, cross-reactive HAI against the heterologous A(H7N3), and 3- to 4-fold higher HAI responses in corresponding ISCOMATRIX subgroups. Similarly, all doses of H7N9 VLP elicited anti-neuraminidase (NA) antibody, with 3- to 4-fold higher responses measured in the corresponding ISCOMATRIX subgroups. The non-homologous H7 vaccine induced both H7N3 and H7N9 HAI but no N9 anti-NA antibodies. A lethal murine wild-type A/Anhui/1/2013 (H7N9) challenge demonstrated 100% survival of all animals receiving A(H7N9) and A(H7N3) vaccine, versus 0% survival in A(H5N1) vaccine and placebo groups. Together, the data demonstrate that recombinant H7N9 vaccine can be rapidly developed that was immunogenic and efficacious supporting testing in man as a pandemic influenza H7N9 vaccine candidate.