Evolution of M. bovis BCG Vaccine: Is Niacin Production Still a Valid Biomarker?

Immunological Characterization of Proteins Expressed by Genes Located in Mycobacterium tuberculosis-Specific Genomic Regions Encoding the ESAT6-like Proteins

The 6 kDa early secreted antigen target (ESAT6) is a low molecular weight and highly immunogenic protein of Mycobacterium tuberculosis with relevance in the diagnosis of tuberculosis and subunit vaccine development. The gene encoding the ESAT6 protein is located in the M. tuberculosis-specific genomic region known as the region of difference (RD)1. There are 11 M. tuberculosis-specific RDs absent in all of the vaccine strains of BCG, and three of them (RD1, RD7, and RD9) encode immunodominant proteins. Each of these RDs has genes for a pair of ESAT6-like proteins. The immunological characterizations of all the possible proteins encoded by genes in RD1, RD7 and RD9 have shown that, besides ESAT-6 like proteins, several other proteins are major antigens useful for the development of subunit vaccines to substitute or supplement BCG. Furthermore, some of these proteins may replace the purified protein derivative of M. tuberculosis in the specific diagnosis of tuberculosis by using interferon-gamma release assays and/or tuberculin-type skin tests. At least three subunit vaccine candidates containing ESAT6-like proteins as antigen components of multimeric proteins have shown efficacy in phase 1 and phase II clinical trials in humans.

International Depository Authority and its Role in Microorganism's Deposition

After the World Trade Organization's agreement on Trade Related Aspect of Intellectual Property Right, patents have come into major play. Patenting of work related to live organisms that have medical, agricultural and other uses is always a tedious, complicated and controversial job. In view of this an agreement called as Budapest Treaty was passed in 1977 for deposition of microorganisms in culture collection centers for patent purpose. To make a culture collection center an IDA the culture center has to follow rules and regulations made in Budapest Treaty. Today several culture collection centers are working as International Depository Authority (IDA) in India and abroad that are storing microorganisms for patent purpose. India has two IDA units; one is Microbial Culture Collection in National Centre for Cell Science Pune, India, and second one is Microbial Type Culture Collection and Gene Bank at Institute of Microbial Technology Chandigarh, India. IDA units are important for valuable sample depositions, supply of cultures, characterization of samples and conservation of biological materials.

Severe Enteropathy and Hypogammaglobulinemia Complicating Refractory Mycobacterium tuberculosis Complex Disseminated Disease in a Child with IL-12Rβ1 Deficiency

PURPOSE

Mendelian susceptibility to mycobacterial disease is a rare clinical condition characterized by a predisposition to infectious diseases caused by poorly virulent mycobacteria. Other infections such as salmonellosis and candidiasis are also reported. The purpose of this article is to describe a young boy affected with various infectious diseases caused by Mycobacterium tuberculosis complex, Salmonella sp, Klebsiella pneumonie, Citrobacter sp., and Candida sp, complicated with severe enteropathy and transient hypogammaglobulinemia.

METHODS

We reviewed medical records and performed flow cytometry staining for lymphocyte populations, lymphocyte proliferation in response to PHA, and intracellular IFN-γ production in T cell PHA blasts in the patient and a healthy control. Sanger sequencing was used to confirm the genetic variants in the patient and relatives.

RESULTS

Genetic analysis revealed a bi-allelic mutation in IL12RB1 (C291Y) resulting in complete IL-12Rβ1 deficiency. Functional analysis demonstrated the lack of intracellular production of IFN-γ in CD3+ T lymphocytes from the patient in response to rhIL-12p70.

CONCLUSIONS

To our knowledge, this is the third patient with MSMD due to IL-12Rβ1 deficiency complicated with enteropathy and hypogammaglobulinemia and the first case of this disease to be described in Colombia.

Defensins: The Case for Their Use against Mycobacterial Infections

Human tuberculosis remains a huge global public health problem with an estimated 1/3rd of the population being infected. Defensins are antibacterial cationic peptides produced by a number of cell types, most notably neutrophil granulocytes and epithelial cells. All three defensin types (α-, β-, and θ-defensins) have antibacterial activities, mainly through bacterial membrane permeabilization. Defensins are effective against Gram-negative and Gram-positive bacteria including mycobacteria and are active both intra- and extracellularly. Mycobacterial resistance has never been demonstrated although the mprF gene encoding resistance in Staphylococcus aureus is present in the Mycobacterium tuberculosis genome. In addition to their antibacterial effect, defensins are chemoattractants for macrophages and neutrophils. There are many cases for their use for therapy or prophylaxis in tuberculosis as well. In conclusion, we propose that there is considerable scope and potential for exploring their use as therapeutic/prophylactic agents and more comprehensive survey of defensins from different species and their bioactivity is timely.