Source: AGRICULTURAL RESEARCH SERVICE submitted to
TOWARDS A VACCINE TO PREVENT TOXOPLASMOSIS
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0414753
Grant No.
(N/A)
Project No.
1245-32000-090-01R
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2008
Project End Date
Jun 30, 2013
Grant Year
(N/A)
Project Director
DUBEY J P
Recipient Organization
AGRICULTURAL RESEARCH SERVICE
RM 331, BLDG 003, BARC-W
BELTSVILLE,MD 20705-2351
Performing Department
(N/A)
Non Technical Summary
(N/A)
Animal Health Component
(N/A)
Research Effort Categories
Basic
50%
Applied
50%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3133510111050%
3133520111050%
Goals / Objectives
Develop an integrated risk model for toxoplasma in the U.S. pork industry.
Project Methods
Will test various drug or vaccine candidates in mice experimentally-infected with Toxoplasma strains of different genotypes.

Progress 10/01/08 to 06/30/13

Outputs
Progress Report Objectives (from AD-416): Develop an integrated risk model for toxoplasma in the U.S. pork industry. Approach (from AD-416): Will test various drug or vaccine candidates in mice experimentally- infected with Toxoplasma strains of different genotypes. This is a multi-institutional five-year agreement funded through National Institutes of Health. The main objective is to develop a protective vaccine for Toxoplasma. Mice are generally used to test the protective efficacy of vaccines because they are susceptible, reagents are available to measure immune parameters, in mice, and they are easily managed in the laboratory. In the present study, we developed a robust oocyst challenge model to study protective immunity in transgenic HLA mice. This oocyst mouse model was used to study efficacy of adjuvants and different vaccine candidates. Entrapment of antigenic peptides in NISV adjuvant system has proven problematic, likely due to solubility and charge of many of these peptides. Consequently we are now moving to use of longer proteins which will circumvent these issues. However, a number of these peptides that we were able to entrap in NISV sufficiently well were tested in the transgenic mice which were challenged with oocysts. Very minimal, if any, protection was observed in these experiments. However what little protection noted was associated with increased KLRG expression on CD8 T cells. Experiments have demonstrated that immunization with the T. gondii protein GRA6 gene can mediate protection against challenge with a type 2 strain of T. gondii in HLA-A11 mice but not A2 mice. This protection measured as reduced parasite number is evident through an in vivo imaging system (IVIS). Flow cytometry analysis demonstrates that protection is associated with induction of TNF-alpha and IFN-gamma producing CD8+ T cells. Further work has cloned additional T. gondii genes for vaccine studies and optimized entrapment of protein into bilosomes for oral delivery studies.

Impacts
(N/A)

Publications


    Progress 10/01/11 to 09/30/12

    Outputs
    Progress Report Objectives (from AD-416): Develop an integrated risk model for toxoplasma in the U.S. pork industry. Approach (from AD-416): Will test various drug or vaccine candidates in mice experimentally- infected with Toxoplasma strains of different genotypes. This is a multi-institutional five year agreement funded through the National Institutes of Health. The main objective is to develop a protective vaccine against Toxoplasma. Mice are generally used to test the protective efficacy of vaccines because (1) mice are susceptible to Toxoplasma, (2) reagents are available to measure immune parameters in mice, and (3) mice are easily managed in the laboratory. This year we developed a robust oocyst challenge model to study protective immunity in transgenic mice human Leukocyte antigen, (HLA) and used this model to study the efficacy of adjuvants and different vaccine candidates. Entrapment of antigenic peptides in non ionic surfactant adjuvant system (NISV) has proven problematic, likely due to solubility and charge of many of these peptides. Consequently we are now moving to the use of longer proteins which will circumvent these issues. A number of these peptides that we were able to entrap in NISV were tested in the transgenic mice/oocyst challenge model. Very minimal protection was observed in these experiments. We are now moving to study immune protection using different oral delivery systems for the presentations of toxoplasma antigens.

    Impacts
    (N/A)

    Publications


      Progress 10/01/10 to 09/30/11

      Outputs
      Progress Report Objectives (from AD-416) Develop an integrated risk model for toxoplasma in the U.S. pork industry. Approach (from AD-416) Will test various drug or vaccine candidates in mice experimentally- infected with Toxoplasma strains of different genotypes. This is a multi-institutional five year agreement funded through National Institutes of Health. The main objective is to develop a protective vaccine for Toxoplasma. Mice are generally used to test the protective efficacy of vaccines because they are susceptible, reagents are available to measure immune parameters, in mice, and they are easily managed in the laboratory. In the present study, pathogenesis of toxoplasmosis was studied in mice of different strains, including Human leukocyte antigen (HLA) transgenic mice infected with different doses of T. gondii strains of different genotypes derived from several countries. Based on many experiments, the decreasing order of infectivity and pathogenicity of oocysts was: interferon gamma gene knock out (KO), HLA 3.11, HLA 2.1, HLA B7, Swiss Webster, C57/black, and BALB/c. Mice fed as few as 1 oocyst of Type I and several atypical strains died of acute toxoplasmosis within 21 days p.i. Type II, and III strains were less virulent. The model developed herein should prove to be extremely useful for testing vaccines because it is possible to accurately quantitate a challenge inoculum, test response to different strains of T. gondii using the same preparations of oocysts which are stable for up to a year, and to have highly reproducible responses to the infection. Project plans, goals, and accomplishments were discussed via conference calls and e-mail; technical advice was provided to the Cooperator in writing and by teleconference.

      Impacts
      (N/A)

      Publications


        Progress 10/01/09 to 09/30/10

        Outputs
        Progress Report Objectives (from AD-416) Develop an integrated risk model for toxoplasma in the U.S. pork industry. Approach (from AD-416) Will test various drug or vaccine candidates in mice experimentally- infected with Toxoplasma strains of different genotypes. This is a multi-institutional five year agreement funded through National Institutes of Health. The main objective is to develop a protective vaccine for Toxoplasma. The infectivity and pathogenicity of three typical genotypes of Toxoplasma gondii (Types III, II, and I) and five atypical oocysts were compared in 4 strains of mice, Swiss Webster outbred mice, BALB/c inbred mice, HLA3.11 and HLA 2.1.; Only minor differences were found with respect to strain of the mouse. Oocysts of the Type I strain were lethal to all strains of mice. This information will be used to test protection in mice immunized with different vaccine candidates. Project plans, goals, and accomplishments were discussed via conference calls and e-mail; technical advice was provided to the Cooperator in writing and by teleconference.

        Impacts
        (N/A)

        Publications


          Progress 10/01/08 to 09/30/09

          Outputs
          Progress Report Objectives (from AD-416) Develop an integrated risk model for toxoplasma in the U.S. pork industry. Approach (from AD-416) Will test various drug or vaccine candidates in mice experimentally- infected with Toxoplasma strains of different genotypes. Significant Activities that Support Special Target Populations This is a multi-institutional five year agreement funded through National Institutes of Health. The main objective is to develop a protective vaccine for Toxoplasma. The infectivity and pathogenicity of three genotypes of Toxoplasma gondii (Types III, II, and I) oocysts were compared in 2 strains of mice, Swiss Webster outbred mice and BALB/c inbred mice; no differences were found with respect to strain of the mouse. Therefore, either strain of mice maybe used in future studies. Project plans, goals, and accomplishments were discussed via conference calls and e-mail; technical advice was provided to the Cooperator in writing and by teleconference.

          Impacts
          (N/A)

          Publications