Methods for detecting a mycobacterium tuberculosis infection
Inventors
Lewinsohn, David M. • Lewinsohn, Deborah A.
Assignees
Oregon Health and Science University • US Department of Veterans Affairs
Publication Number
US-9173930-B2
Publication Date
2015-11-03
Expiration Date
2030-11-19
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Abstract
Methods for detecting an infection with Mtb in a subject are disclosed. The methods include detecting the presence of CD8+ T cells that specifically recognize an Mtb polypeptide. The methods include in vitro assays for detecting the presence of CD8+ T cells in a biological sample, and in vivo assays that detect a delayed type hypersensitivity reaction. The methods also include detecting Mtb polypeptides and polynucleotides.
Core Innovation
Methods for detecting an infection with Mycobacterium tuberculosis (Mtb) in a subject are disclosed. The methods involve detecting the presence of CD8+ T cells and/or CD4+ T cells that specifically recognize an Mtb polypeptide. These methods include in vitro assays that detect the presence of these T cells in a biological sample, and in vivo assays that detect a delayed type hypersensitivity reaction. The methods also include detecting specific Mtb polypeptides and polynucleotides either alone or in combination.
The problem being solved addresses the difficulty in accurately and early diagnosing tuberculosis, which is critical for controlling its spread. Current diagnostic methods such as the tuberculin skin test have limitations in sensitivity and specificity, especially in differentiating vaccinated individuals from infected ones, and in diagnosing TB in children due to challenges in culturing Mtb. Additionally, there are no effective vaccines or therapies that induce a robust immune response, especially CD8+ T cell responses, to Mtb.
Claims Coverage
The claims include two main independent claims directed to methods for detecting an immune response to Mycobacterium tuberculosis, focusing on ex vivo and intradermal detection assays involving specific Mtb polypeptides.
Use of specific Mtb polypeptides to detect T cell immune response ex vivo
The method comprises contacting a biological sample containing T cells with one or more Mtb polypeptides selected from specified sequences (SEQ ID NOs: 1-16 and at least nine to twenty consecutive amino acids thereof) presented by antigen presenting cells, and performing an enzyme-linked immunospot assay detecting interferon-γ to determine if the T cells specifically recognize these polypeptides, indicating an immune response to Mtb.
Administration of Mtb polypeptides intradermally to detect delayed type hypersensitivity
The method involves intradermally administering an effective amount of one or more Mtb polypeptides from the specified sequences to a subject, and measuring induration, swelling, redness, or dermatitis at the injection site after at least 48 hours. A delayed type hypersensitivity reaction of greater than 0.5 cm indicates an immune response to Mtb.
Detection of specific T cell recognition using capture and labeled antibodies against interferon-γ
This method includes contacting T cell-containing biological samples with specified Mtb polypeptides and antigen presenting cells, capturing secreted interferon-γ with immobilized monoclonal antibodies, and detecting the presence of T cells recognizing Mtb polypeptides by binding of labeled antibodies to the interferon-γ complex, indicating an immune response to Mtb.
The independent claims cover methods using defined Mtb polypeptides to detect immune responses to Mtb by ex vivo T cell assays measuring interferon-γ production and in vivo skin tests measuring delayed type hypersensitivity, employing defined amino acid sequences and specific immunological detection techniques.
Stated Advantages
Improved diagnostic methods increase sensitivity and specificity for detecting tuberculosis infection compared to current tuberculin skin tests.
Ability to detect both latent and active Mtb infection.
Use of defined Mtb polypeptides allows for more precise detection of specific CD8+ and CD4+ T cell responses.
Methods support early diagnosis to reduce morbidity and mortality associated with tuberculosis.
Documented Applications
Use in diagnosing Mtb infection in subjects by detecting T cell responses to specific Mtb polypeptides from blood or other biological samples.
Intradermal skin tests employing Mtb polypeptides to detect delayed type hypersensitivity reactions indicating Mtb exposure.
Detection of Mtb polypeptides or polynucleotides in biological samples for diagnosis.
Monitoring progression of tuberculosis infection and assessing effectiveness of therapy by repeated immunological assays.
Use in animal models (mouse and guinea pig) for studying infection and vaccine or therapeutic efficacy.
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