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Methods and reagents for vaccination which generate a CD8 T cell immune response

a technology reagents, which is applied in the field of vaccines, can solve the problems of inability to generate high levels of cd8 t cells by immunization, impede the development of vaccines against several diseases, and no means of vaccinating against malaria infection, and achieve good boosting effect to a primed ctl response

Inactive Publication Date: 2004-07-08
OXXON THERAPEUTICS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0023] It has now been discovered that non-replicating and replication-impaired strains of poxvirus provide vectors which give an extremely good boosting effect to a primed CTL response. Remarkably, this effect is significantly stronger than a boosting effect by wild type poxviruses. The effect is observed with malarial and other antigens such as viral and tumor antigens, and is protective as shown in mice and non-human primate challenge experiments. Complete rather than partial protection from sporozoite challenge has been observed with the novel immunization regime.

Problems solved by technology

A general problem in vaccinology has been an inability to generate high levels of CD8 T cells by immunization.
This has impeded the development of vaccines against several diseases including malaria.
However, despite this progress there is still no means of vaccinating against malaria infection which has been shown to be effective in field trials.
A major problem has been the identification of a means of inducing a sufficiently strong immune response in vaccinated individuals to protect against infection and disease.
So, although many malaria antigens are known that might be useful in vaccinating against malaria the problem has been how to deliver such antigens or fragments of them known as epitopes, which are recognized by cells of the immune system, in a way that induces a sufficiently strong immune response of a particular type.
Because of the expense and limited availability of chimpanzees most laboratory studies of malaria are performed in mice, using the rodent malaria species P. berghei or P. yoelii.
However, an effective means of immunizing with subunit vaccines by the induction of sufficiently high levels of CD8+T lymphocytes to protect effectively against malaria sporozoite infection has not previously been demonstrated.
Only low levels of antibody responses were observed with this prime boost regime and the results were considered disappointing.
However, this did not translate into enhanced protective efficacy as a greater reduction in viral burden and attenuation of CD4 T cell loss was seen in the DNA primed and boosted animals.
Reversing the order of immunization led to loss of all protective efficacy and the authors suggested that this might be related to infection of liver cells by vaccinia, resulting in localization of CTLs in the liver to protect against the hepatocytic stages of malaria parasites.
However, there are two limitations to these findings in terms of their potential usefulness.
Firstly, the immunogenicity induced was only sufficient to achieve partial protection against malaria and even this was dependent on a highly immunogenic priming immunization with an unusual replicating recombinant influenza virus.
Secondly, because of the potential and documented side-effects of using these replicating viruses as immunogens these recombinant vectors are not suitable for general human use as vaccines.
The late block in viral replication does not prevent efficient expression of recombinant genes in MVA.

Method used

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  • Methods and reagents for vaccination which generate a CD8 T cell immune response
  • Methods and reagents for vaccination which generate a CD8 T cell immune response
  • Methods and reagents for vaccination which generate a CD8 T cell immune response

Examples

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example 1

[0083] Materials and Methods

[0084] Generation of the Epitope Strings

[0085] The malaria epitope string was made up of a series of cassettes each encoding three epitopes as shown in Table 1, with restriction enzyme sites at each end of the cassette. Each cassette was constructed from four synthetic oligonucleotides which were annealed together, ligated into a cloning vector and then sequenced to check that no errors had been introduced. Individual cassettes were then joined together as required. The BamHI site at the 3' end of cassette C was fused to the Bg1II site at the 5' end of cassette A, destroying both restriction enzyme sites and encoding a two amino acid spacer (GS) between the two cassettes. Cassettes B, D and H were then joined to the string in the same manner. A longer string containing CABDHFE was also constructed in the same way.

5TABLE 1 CTL Epitopes of the Malaria (M) String Amino acid HLA Cassette Epitope Sequence DNA sequence Type restriction A Ls8 KPNDKSLY AAGCCGAACG...

example 2

[0131] Immunogenicity Studies in Mice

[0132] Previous studies of the induction of CTL against epitopes in the circumsporozoite (CS) protein of Plasmodium berghei and Plasmodium yoelii have shown variable levels of CTL induction with different delivery systems. Partial protection has been reported with plasmid DNA (Sedegah et al. 1994), influenza virus boosted by replicating vaccinia virus (Li et al. 1991), adenovirus (Rodrigues et al 1997) and particle delivery systems (Schodel et al. 1994). Immunisation of mice intramuscularly with 50 micrograms of a plasmid encoding the CS protein produced moderate levels of CD8+cells and CTL activity in the spleens of these mice after a single injection (FIGS. 3, 4A-4D).

[0133] For comparison groups of BALB / c mice (n=5) were injected intravenously with 10.sup.6 ffu / pfu of recombinant vaccinia viruses of different strains (WR, NYVAC and MVA) all expressing P. berghei CSP. The frequencies of peptide-specific CD8+T cells were measured 10 days later in...

example 3

[0167] Malaria Challenge Studies in Mice

[0168] To assess the protective efficacy of the induced levels of CD8+T cell response immunised BALB / c or C57BL / 6 mice were challenged by intravenous injection with 2000 or 200 P. berghei sporozoites. This leads to infection of liver cells by the sporozoites. However, in the presence of a sufficiently strong T lymphocyte response against the intrahepatic parasite no viable parasite will leave the liver and no blood-stage parasites will be detectable. Blood films from challenged mice were therefore assessed for parasites by microscopy 5-12 days following challenge.

[0169] BALB / c mice immunised twice with a mixture of two plasmid DNAs encoding the CS protein and the TRAP antigen, respectively, of P. berghei were not protected against sporozoite challenge. Mice immunised twice with a mixture of recombinant MVA viruses encoding the same two antigens were not protected against sporozoite challenge. Mice immunised first with the two recombinant MVAs ...

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Abstract

New methods and reagents for vaccination are described which generate a CD8 T cell immune response against malarial and other antigens such as viral and tumour antigens. Novel vaccination regimes are described which employ a priming composition and a boosting composition, the boosting composition comprising a non-replicating or replication-impaired pox virus vector carrying at least one CD8 T cell epitope which is also present in the priming composition.

Description

[0001] This application is a divisional of Ser. No. 09 / 454,204, filed on Dec. 9, 1999, which is a continuation of, and claims priority to International Application No. PCT / GB98 / 01681, filed 9 Jun. 1998 which designates the United States, and which is a continuing application of GB9711957.2 filed 9 Jun. 1997. The entire teachings of U.S. application Ser. No. 09 / 454,204, PCT / GB98 / 01681 and GB9711957.2 are incorporated herein by reference.BACKGROUND OF INVENTION[0002] A general problem in vaccinology has been an inability to generate high levels of CD8 T cells by immunization. This has impeded the development of vaccines against several diseases including malaria.[0003] Plasmodium falciparum malaria causes hundreds of millions of malaria infections each year and is responsible for 1-2 million deaths annually. The development of an effective vaccine against malaria is thus a major priority for global public health. A considerable body of immunological research over the last twenty years...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C12N15/09A61K35/76A61K38/17A61K39/00A61K39/015A61K39/145A61K39/21A61K39/275A61K39/39A61K45/00A61P31/12A61P31/18A61P33/06A61P35/00A61P37/04C07K7/06C07K7/08C07K14/11C07K14/16C07K14/445C12N7/00C12N15/30C12N15/48C12N15/86C12N15/861C12N15/863
CPCA61K38/1709A61K2039/5258A61K39/015A61K39/145A61K39/21A61K39/39A61K2039/51A61K2039/5256A61K2039/53A61K2039/54A61K2039/545A61K2039/55522A61K2039/57C07K14/005C07K14/445C12N15/86C12N2710/10343C12N2710/24043C12N2710/24143C12N2740/15034C12N2740/16134C12N2740/16234C12N2760/16122C12N2760/16134A61K39/0011A61K39/12A61P31/12A61P31/16A61P31/18A61P31/20A61P33/06A61P35/00A61P37/04Y02A50/30
Inventor MCMICHAEL, ANDREWHILL, ADRIAN V.S.GILBERT, SARAH C.SCHNEIDER, JORGPLEBANSKI, MAGDALENAHANKE, TOMASSMITH, GEOFFREY L.BLANCHARD, TOM
Owner OXXON THERAPEUTICS LTD
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