Mycothiol acetyltransferase (Rv0819) of Mycobacterium tuberculosis is a potential biomarker for direct diagnosis of tuberculosis using patient serum specimens.

Mycobacterium tuberculosis infection constitutes a global threat that results in significant morbidity and mortality worldwide. Efficient and early diagnosis of tuberculosis (TB) is of paramount importance for successful treatment. The aim of the current study is to investigate the mycobacterial mycothiol acetyltransferase Rv0819 as a potential novel biomarker for the diagnosis of active TB infection. The gene encoding Rv0819 was cloned and successfully expressed in Escherichia coli. The recombinant Rv0819 was purified using metal affinity chromatography and was used to raise murine polyclonal antibodies against Rv0819. The raised antibodies were employed for direct detection of Rv0819 in patient serum samples using dot blot assay and competitive enzyme-linked immunosorbent assay (ELISA). Serum samples were obtained from 68 confirmed new TB patients and 35 healthy volunteers as negative controls. The dot blot assay showed sensitivity of 64·7% and specificity of 100%, whereas the competitive ELISA assay showed lower sensitivity (54·4%) and specificity (88·57%). The overall sensitivity of the combined results of the two tests was found to be 89·7%. Overall, the mycobacterial Rv0819 is a potential TB serum biomarker that can be exploited, in combination with other TB biomarkers, for efficient and reliable diagnosis of active TB infection. SIGNIFICANCE AND IMPACT OF THE STUDY: The early and accurate diagnosis of tuberculosis infection is of paramount importance for initiating treatment and avoiding clinical complications. Most current diagnostic tests have poor sensitivity and/or specificity and in many cases they are too expensive for routine diagnostic testing in resource-limited settings. In the current study, we examined a novel mycobacterial serum biomarker, namely mycothiol acetyltransferase Rv0819. The antigen was detectable in serum specimens of a significant number of tuberculosis patients. This article proves the importance of Rv0819 and paves the way towards its future use as a useful diagnostic marker for tuberculosis infection.

Successful detection, expression and purification of the alternatively spliced truncated Sm14 antigen of an Egyptian strain of Schistosoma mansoni.

Schistosoma mansoni causes intestinal schistosomiasis, a disease that is prevalent in several regions worldwide. To date, a protective vaccine against S. mansoni is still lacking. Several promising antigens have been discovered and evaluated for vaccine protection, such as Sm14 and Sm28GST. In this short communication, we report the successful detection of an alternatively spliced truncated form of Sm14 which was highly expressed in an Egyptian strain of S. mansoni. This truncated Sm14 (TrSm14) protein was formerly reported to be practically non-existent and its complementary DNA (cDNA) was thought to be 'a rare misprocessing of mRNA precursor'. Our finding demonstrates that there is inter-strain variation in the S. mansoni transcriptome and subsequently in the role/function of the expressed proteins. We expressed TrSm14 successfully in Escherichia coli as a fusion protein with the schistosomal antigen Sm28GST. The fusion protein was purified using metal affinity chromatography and was found to be reactive with serum from S. mansoni-infected patients. This suggests a possible diagnostic value for this protein in detection of anti-schistosomal antibodies. In addition, this fusion protein could offer a potential bivalent vaccine candidate against S. mansoni that is worthy of further investigation.