Size-variable strain-specific protective antigen for Potomac horse fever

a strain-specific, potomac horse fever technology, applied in the field of size-variable strain-specific protective antigen for potomac horse fever, can solve the problems of substantial economic loss to the equine industry, all attempts to reveal the mode of transmission of risticii/risticii have failed, etc., and achieve the effect of protecting the immune response and more effective vaccines

Inactive Publication Date: 2008-03-20
DUTTA SUKANTA +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]The present invention is based on the discovery that strains of Ehrlichia risticii express surface antigens that are specific to the strain. These surface-expressed proteins are termed strain-specific antigens (SSAs). These antigens have now been isolated and purified from the respective strains. The SSAs of the present invention may be used to detect Ehrlichia risticii strains and to generate a protective immune response against E. risticii strains, leading to the development of more effective vaccines against PHF.

Problems solved by technology

Although most of the rickettsial pathogens are transmitted by arthropod vectors and the seasonality of PHF also suggests this, all attempts to reveal the mode of transmission of E. risticii have been unsuccessful.
E. risticii infection is responsible for substantial economic loss to the equine industry.

Method used

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  • Size-variable strain-specific protective antigen for Potomac horse fever
  • Size-variable strain-specific protective antigen for Potomac horse fever
  • Size-variable strain-specific protective antigen for Potomac horse fever

Examples

Experimental program
Comparison scheme
Effect test

example 1

Isolation of Strain Specific Surface Antigen Gene of Ehrlichia risticii

Ehrlichia risticii Strains and DNA Preparation:

[0034]Two different strains of E. risticii were used for this study. The original E. risticii strain (25D) was isolated in 1984, during the initial outbreaks of PHF near the Potomac River bank in Maryland and Virginia. Recently the inventors isolated a new strain of E. risticii (90-12) from a vaccinated horse suffering from clinical PHF. These two strains of the organism were grown separately in human histiocyte cells and purification was accomplished over linear Renografin (Squibb, N.J.) density gradient centrifugation.

Propagation of Ehrlichia risticii in Cell Culture:

[0035]E. risticii strains were propagated a human histiocyte (HH) cell line (American Type culture Collection #U937). These cells were grown in RPMI 1640 medium (Flow Laboratories, McLean, Va.), supplemented with 4 mM L-glutamine (M.A. Bioproducts, Walkersville, Md.), and 15% fetal calf serum (Gibco L...

example 2

Isolation of Strain Specific Surface Antigen Gene of Ehrlichia risticii ATCC Type Strain

[0145]Using the procedures outlined in Example 1, the gene encoding the 50 kDa SSA from the ATCC type strain was isolated. The gene sequence and the amino acid sequence encoded thereby is shown in FIG. 4 (SEQ ID NO: 7 and 8).

example 3

Challenge Experiments

Summary

[0146]To study the role of major antigens of E. risticii in protective immune response, we expressed the genes of the 55 kDa, 51 kDa and 85 ′50 kDa-strain-specific antigens of the 90-12 85 kDa antigen and 25-D (50 kDa antigen strains in Escherichia coli. Mice immunized with these purified recombinant proteins of E. risticii developed strong and specific humoral immune response. The recombinant 85 kDa antigen of the 90-12 strain protected mice against challenge infection with both E. risticii strains, whereas its homologue from the 25-D strain, the recombinant 50 kDa antigen, protected mice against only the homologous strain challenge, but not against the heterologous 90-12 strain. Sera from mice immunized with the 85- or 50-kDa antigens did not inhibit the replication of cell-free Ehrlichia in in vitro neutralization assays. Sera from normal mice and mice immunized with other antigens caused non-specific neutralization of E. risticii. Immunoglobulin G fro...

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Abstract

An isolated and purified antigen which is expressed by a wild-type E. risticii strain and is specific to the stain. The present invention also relates to nucleic acid constructs which encode the antigen, expression vectors, transformed host cells, and methods for producing the antigen.

Description

[0001]This application is a Division of U.S. application Ser. No. 10 / 055,536, filed Jan. 23, 2002, now co-pending, which is a Division of U.S. application Ser. No. 09 / 157,257, filed on Sep. 18, 1998, now U.S. Pat. No. 6,375,954, which claims priority to provisional application 60 / 059,252, filed Sep. 18, 1997, all of which are incorporated herein in their entirety by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to isolated and purified antigen which is expressed by a wild-type E. risticii strain and is specific to the strain. The present invention also relates to nucleic acid constructs which encode the antigen, expression vectors, transformed host cells, and methods for producing the antigen.[0004]2. Discussion of the Background[0005]Potomac horse fever (PHF), also known as equine monocytic ehrlichiosis (EME), is an acute infectious disease of horses. PHF was initially recognized in 1979 in areas along the Potomac river in M...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61K39/00A61P43/00C07K14/29
CPCA61K39/00C07K14/29A61K2039/55566A61P43/00Y02A50/30
Inventor DUTTA, SUKANTABISWAS, BISWAJITVEMULAPALLI, RAMESH
Owner DUTTA SUKANTA
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