Tuberculosis (TB), caused by M. tuberculosis infection, continues to be one of the most prevalent infectious diseases worldwide. The WHO has also estimated that one third of the world population would be infected with latent M. tuberculosis (LTBI), where individuals are do not exhibit active disease but are with a high risk of reactivation. Primary infection leads to active TB in less than 10% of infected individuals, as the immune system is usually able to contain, but not eliminate, the infection, leading to LTBI. Latency can persist throughout lifetime, but weakness of the immune system, due to therapeutical treatments (in AIDS, organ transplant cases…), malnutrition or old age of the host, can lead to reactivation. The situation is aggravated by the high rate of M. tuberculosis- HIV co-infection.
Interferon gamma release assays (IGRAs) represent the most novel TB infection diagnostic assays and have been well received in most developed countries, but current tests are not able to discriminate active TB and LTBI. The lack of a gold standard for diagnosing LTBI has thus remained a main hurdle.
Thus, the present invention relates to a mixture of peptides derived from the M. tuberculosis antigen Rv2626c that, unlike current commercial tests, discriminates latent TB individuals from patients with tuberculosis active disease and from healthy subjects.
In addition, the present invention also relates to a combination of these peptides with the antigens CFP-10 and ESAT-6 (which only discriminate M. tuberculosis infection, either latent or active) this combination being able, in one test, to discriminate between the three groups of individuals: healthy subjects, individuals with LTBI and patients with active TB.
Scientific Publication(s):
EBioMedicine., 2015 May 30, Peña D. et al., A Mycobacterium tuberculosis Dormancy Antigen Differentiates Latently Infected Bacillus Calmette-Guérin-vaccinated Individuals, doi: 10.1016/j.ebiom.2015.05.026.