Live bacterial vaccines for viral infection prophylaxis or treatment

Abstract

The present invention provides a vaccine, method of use, and kit employing genetically isolated and stabilized, live attenuated bacterial strains including Salmonella that express one or more avian influenza antigens for use in live vaccine compositions that can be orally administered to an individual to protect against avian influenza. Genetic stabilization may be achieved through deletion of IS200 elements and bacteria phage and prophage elements. The bacterial strains may be genetically isolated from external phage infection by constitutive expression of a P22 phage repressor. Nucleic acid sequences encoding antigenic hemagglutinin and neuraminidase avian influenza proteins, having at least one modified codon for optimum expression when transferred into a prokaryotic microorganism for improved immunogenicity

Description

FIELD OF THE INVENTION[0001]This invention is generally in the field of live bacterial vaccines for viral infection prophylaxis or treatment.BACKGROUND OF THE INVENTION[0002]Citation or identification of any reference herein, or any section of this application shall not be construed as an admission that such reference is available as prior art to the present application.[0003]There are three types of influenza viruses Influenza A, B, and C. Influenza types A or B viruses cause epidemics of disease almost every winter. In the United States, these winter influenza epidemics can cause illness in 10% to 20% of people and are associated with an average of 36,000 deaths and 114,000 hospitalizations per year. Influenza type C infections cause a mild respiratory illness and are not thought to cause epidemics. Influenza type A viruses are divided into subtypes based on two proteins on the surface of the virus. These proteins are termed hemagglutinin (H) and neuraminidase (N). Influenza A vir...

AI Technical Summary

Benefits of technology

[0022]The present invention provides live attenuated bacterial strains that express one or more immunogenic polypeptide antigens of a virus, preferably an avian influenza virus, that is effective in raising an immune response in mammals.

Problems solved by technology

The pathogenicity of the initial 1918 H1N1 has not been equaled by any of the latter H1N1, H2N2 or H3N2 subtypes, although infection from some subtypes can be severe and result in death.

Furthermore, oseltamivir (Tamiflu®) was ineffective in 50% of avian influenza patients in Thailand (Tran et al.

Such changes may alter the antigenic nature of the protein and reduce the effectiveness of vaccines not matched to the new variant.

The optimum way of dealing with a human pandemic virus would be to provide a clinically approved well-matched vaccine (i.e., containing the hemagglutinin and / or neuraminidase antigens of the emerging human pandemic strain), but this cannot easily be achieved on an adequate timescale because of the time consuming method of conventional influenza vaccine production in chicken eggs.

However, because some of the vaccine virus may be produced in canine tumor cells (e.g., MDCK), there is concern for contamination of the vaccine by cancer causing elements.

Moreover, both must undergo a labor intensive and technically challenging purification process, with a total production time of 3 to 6 months.

Therefore, traditionally produced vaccine produced before a pandemic, would likely be generated based upon an avian influenza virus and its antigens more than a year earlier and therefore may not be well matched to an emerging variant and could result in only partial protection.

Live Salmonella vaccines have not had deletions in phage elements such as phage recombinases which exist in Salmonella, such that the phage are no longer capable of excision and reinfection of other susceptible strains.

Furthermore, the codon usage of the viral genome is not optimal for bacterial expression.

Further, these authors used antibiotic-containing plasmids and did not use stable chromosomal localization.

However, Khan et al. did not describe a vaccine for avian influenza virus.

They did not describe the appropriate antigens for an avian influenza virus, the hemagluttinin and neuraminidase, and did not describe how to genetically match an emerging avian influenza virus.

Furthermore, it has become apparent that certain assumptions, and experimental designs described by Khan et al. regarding live avian influenza vaccines would not be genetically isolated or have improved genetic stability in order to provide a live vaccine for avian influenza that would be acceptable for use in humans.

Images