Title:  Human/simian chimeric hepatitis A virus vaccine

United States Patent:  6,146,643

Assignee:  The United States of America as represented by the Secretary of the (Washington, DC)

Filed:  June 7, 1995

The present invention relates, in general, to a substantially pure preparation of the simian hepatitis A viral isolate AGM-27; a substantially pure preparation of the genomic DNA of simian hepatitis A viral isolate AGM-27; a pharmaceutical composition comprising the simian hepatitis A viral isolate AGM-27; a method of preventing hepatitis A in an animal; and a vaccine comprising the simian hepatitis A viral isolate AGM-27.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a simian hepatitis A viral isolate.

In one embodiment, the present invention relates to a substantially pure preparation of the simian hepatitis A viral isolate AGM-27. The virus was isolated in primary African Green Monkey Cells shown to be free of contaminating viruses and is therefore suitable for oral administration after completion of requisite safety tests. The fact that none of the strains of hepatitis A virus isolated from man until now has characteristics similar to those of AGM-27 and tests in several primate species indicates that this strain will be attenuated for in humans. Therefore, this strain can be expected to be suitable for use as a live vaccine against hepatitis A. Transmission experiments in primates can be used to determine whether this strain can cross-protect against wild type human strains.

In another embodiment, the present invention relates to a substantially pure preparation of the genomic DNA of simian hepatitis A viral isolate AGM-27. In one preferred embodiment, the genomic DNA has the sequence shown in SEQ ID NO: 1.

In a further embodiment, the present invention relates to a pharmaceutical composition comprising the above-described simian hepatitis A viral isolate AGM-27 in an amount effective to prevent hepatitis A in an animal, and a pharmaceutically acceptable diluent, carrier, or excipient. The pharmaceutical composition of the invention includes the viral isolate AGM-27 in a quantity selected depending on the route of administration (preferably, oral (P.O.), subcutaneous, I.M., or I.V.). Appropriate concentrations and dosage unit sizes can be readily determined by one skilled in the art. Suitable amounts might be expected to fall within the range of approximately 10³ to approximately 10⁸ tissue culture infectious doses.

In another embodiment the present invention relates to a method of preventing hepatitis A in an animal comprising administering to the animal the above-described simian hepatitis A viral isolate AGM-27 under conditions such that said hepatitis A is prevented. One skilled in the art will appreciate that the amounts to be administered for any particular treatment protocol can readily be determined.

In a further embodiment, the present invention relates to a vaccine comprising the above-described simian hepatitis A viral isolate AGM-27 in an amount effective to prevent hepatitis A in an animal and a pharmaceutically acceptable diluent, carrier, or excipient. In one preferred embodiment, the animal is selected from the group consisting of humans, apes, and monkeys.

It has been demonstrated that attenuation of one isolate of virulent HAV occurred in parallel with its adaptation to growth in cell culture. Wild-type HAV isolated from clinical materials grows extremely poorly in cell culture: in vivo replication usually cannot be detected in primate cells until 10-12 weeks after inoculation. It is intersecting, therefore, to find that wild type simian HAV grows in primary AGMK cells or the FRhK-4 cell line without prior adaption. While its ability to grow directly in FRhK-4 or AGMK cells distinguished AGM-27 from the wild-type HM-175, its inability to grow in CV-1 cells distinguished it from the cell culture-adapted variant of the human virus.

These structural and biological data demonstrate that the AGM-27 strain differs significantly from any other known strains of HAV and is a good model for further investigation of the molecular basis of HAV cell-culture adaptation and attenuation. The genome of AGM-27 differs from those of human strains in approximately 1400 nucleotide positions while the human wild-type and attenuated strains of HM-175 differ only in 24 nucleotide positions. A live vaccine based on the AGM-27 strain can be expected to be significantly safer in terms of low reversion to a virulent strain. Thus, chimeric viruses between a human attenuated strain and AGM-27 strain can be designed. These chimeras will have structural regions from the human strain in order to have immunogenic properties of human viruses and nonstructural regions from AGM-27 (especially 2B, 2C and 5' end non-coding region; see Emerson, S. U. et al. (1989) In: R. A. Lerner et al (eds) Modern approaches to new vaccines including prevention of AIDS, Cold Spring Harbor Laboratory, pp. 427-430).

Claim 1 of 5 Claims

What is claimed is:

1. A hepatitis A virus having a genome consisting of a human attenuated hepatitis A virus sequence wherein the 5' noncoding region has been replaced by the 5' noncoding region of simian hepatitis A virus AGM-27.

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