Recombinant subunit west nile virus vaccine for protection of human subjects

Abstract

A West Nile virus vaccine for human use is described that preferably contains a recombinantly produced form of truncated West Nile virus envelope glycoprotein and aluminum adjuvant. The vaccine is acceptable for use in the general population, including immunosuppressed, immunocompromised, and immunosenescent individuals. The vaccine is safe and effective for use in all healthy and at-risk populations. A pharmaceutically acceptable vehicle may also be included in the vaccine.

Description

RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Patent Application No. 61 / 182,754, filed May 31, 2009, the disclosures and drawings of which prior application are hereby incorporated by reference in their entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]This invention was made with government support under NS052139-04 and W81XWH-06-2-0035 awarded by NIH and the DoD, respectively. The government has certain rights in the invention.SEQUENCE LISTING[0003]No Sequence Listings are claimed in this application.FIELD OF THE INVENTION[0004]The invention relates generally to the field of vaccines. The present invention relates to a vaccine designed to protect humans from disease caused by the West Nile virus. Specifically, the vaccine comprises a truncated version of the recombinant envelope (E) glycoprotein from West Nile virus produced in an insect cell production system and an aluminum-based adjuvant.BACKGROUND OF THE INVENTION[0005]The famil...

AI Technical Summary

Benefits of technology

[0025]The present invention provides a unique human vaccine to protect against disease associated with WNV infection. The vaccine is formed by the combination of a recombinant subunit protein derived from WNV envelope protein and aluminum hydroxide adjuvant. The vaccine is capable of inducing a relevant protective immune response and has demonstrated an acceptable safety profile in vaccinated human volunteers. This unique vaccine formulation depends upon a novel, properly folded recombinant envelope subunit protein (“West Nile 80E” or “WN-80E”) combined with an aluminum-based adjuvant to produce the vaccine formulation HBV-002. This vaccine (1) induces relevant, protective immune responses, such as virus neutralizing antibody in healthy human volunteers and (2) maintains an acceptable safety profile for administration to healthy and immunocompromised individuals.

Problems solved by technology

In addition, in a high percentage of the non-fatal cases, permanent neurological disabilities result.

Recent studies have shown that recovery from viral infection requires significantly more time than originally thought.

The neurological damage done by the virus is slow to heal and, in some cases, is permanent.

The clinical findings are significantly worse in elderly patients.

Thus, there is significant morbidity and mortality associated with WN disease, especially among the elderly / immunosenescent, immunocompromised, and immunosuppressed populations.

However, the use of live-attenuated virus and inactivated virus methods to develop vaccines for other flaviviruses has met significant challenges.

For example, a significant amount of effort has been invested in developing candidate live-attenuated dengue vaccine strains; however, many of the strains tested have proven unsatisfactory (see, e.g., Eckels, K. H. et al., Am. J. Trop. Med. Hyg. (1984) 33:684-689; Bancroft, W. H. et al., Vaccine (1984) 149:1005-1010; McKee, K. T., et al., Am. J. Trop. Med. Hyg. (1987) 36:435-442).

No significant efforts to develop a WNV vaccine utilizing traditional live-attenuated methods have been made.

While the use of live-attenuated chimeric methods has advantages over traditional live-attenuated methods, the chimeric methods are still plagued by difficulties faced in developing properly attenuated strains and in the case of a DENV vaccine achieving balanced, tetravalent responses against the four dengue viruses.

Furthermore, live-attenuated approaches may not be appropriate for vaccines targeting encephalitic diseases due to an elevated risk factor or for target populations with compromised immune systems.

As with live-attenuated virus methods, the use of inactivated virus methods for certain flaviviruses has not guaranteed success with other flaviviruses.

For example, efforts to develop inactivated DENV or WNV vaccines have met with limited success.

This method is limited by the ability to obtain adequate viral yields from cell culture systems.

Despite these advantages, the ability to induce consistent and robust immune responses in humans, particularly antibody responses, continues to be a major hurdle to this approach.

Additionally, DNA vaccines face additional regulatory scrutiny due to concerns about integration of plasmid sequences in the host genome and the potential of generating auto-antibodies to double stranded DNA.

To date no DNA vaccine has been approved for human use and it is not clear that this approach will ever be deemed appropriate for a prophylactic human vaccine.

While the potential to generate relevant and robust immune responses exist, there are challenges associated with use of recombinant subunit protein vaccines.

These attempts have been plagued by low yields, improper processing of the flavivirus proteins, and moderate to poor immunogenicity (Eckels, K H and Putnak, R, Adv.

The E subunits expressed in yeast cells demonstrated improved structure over bacterial systems, but still faced problems with hyper-glycosylation, yields, and product uniformity.

However, these patents and publications do not address or predict a vaccine formulation based solely on E that has demonstrated applicability for human use.

In the development of flavivirus vaccines for humans it has been difficult to predict safety and immunogenicity of candidate vaccines in human subjects based on preclinical data in animal models.

This has proved challenging for many of the live-attenuated virus vaccine candidates that have advanced to human clinical trials.

However, there are numerous examples of non-replicating virus vaccine candidates which have shown good safety and protective efficacy in preclinical models, which failed to function as safe and effective vaccines in humans (e.g. inactivated RSV vaccine; Murphy et al., J. Clin. Microbiol. (1986) 24:197-202).

Thus, there can be multiple challenges associated to developing safe and effective vaccines for flaviviruses and development often requires years of trial and error.

Furthermore, preclinical studies based on animal models may not be predictive of vaccine performance in human subjects; and therefore, human data is critical in demonstrating the utility of a candidate vaccine.

There are intrinsic difficulties and potential shortcomings associated with each of the three candidate vaccines.

Under-attenuation of the virus may result in virus-related adverse events, whereas over-attenuation may abrogate vaccine efficacy.

Particularly worrisome with the Chimerivax technology is the safety profile of the YF 17D vaccine (which serves as the backbone for the chimera) in the elderly and immunocompromised.

In light of the key association between morbidity and mortality of WNV infection in elderly subjects, the application of a live attenuated vaccine approach to this disease target is highly questionable from a safety perspective and thus the first two vaccine candidates do not offer a safe solution to the need for a West Nile vaccine.

Naked DNA vaccines are unproven for any infectious disease at this time, and the issue of potential immunopathology due to the induction of an autoimmune reaction to the DNA over the long term is unresolved.

Low levels of neutralizing antibodies were elicited; however, clinical development of this DNA vaccine has apparently been abandoned, likely linked to safety challenges.

Thus, DNA vaccines do not offer a safe and effective solution for development of a WNV vaccine for human use.

Despite these efforts, a WNV vaccine for human use that fully meets these conditions has yet to be established.

This represents a significant challenge in WNV vaccine development, and to date no vaccine approach has been shown to adequately address all aspects of this technical problem.

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