Expression and purification of diagnostically sensitive mycobacterial (Mycobacterium bovis) antigens and profiling of their humoral immune response in a rabbit model

Molecular Insight into Mycobacterium tuberculosis Resistance to Nitrofuranyl Amides Gained through Metagenomics-like Analysis of Spontaneous Mutants

We performed synthesis of new nitrofuranyl amides and investigated their anti-TB activity and primary genetic response of mycobacteria through whole-genome sequencing (WGS) of spontaneous resistant mutants. The in vitro activity was assessed on reference strain Mycobacterium tuberculosis H37Rv. The most active compound 11 was used for in vitro selection of spontaneous resistant mutants. The same mutations in six genes were detected in bacterial cultures grown under increased concentrations of 11 (2×, 4×, 8× MIC). The mutant positions were presented as mixed wild type and mutant alleles while increasing the concentration of the compound led to the semi-proportional and significant increase in mutant alleles. The identified genes belong to different categories and pathways. Some of them were previously reported as mediating drug resistance or drug tolerance, and counteracting oxidative and nitrosative stress, in particular: Rv0224c, fbiC, iniA, and Rv1592c. Gene-set interaction analysis revealed a certain weak interaction for gene pairs Rv1592–Rv1639c and Rv1592–Rv0224c. To conclude, this study experimentally demonstrated a multifaceted primary genetic response of M. tuberculosis to the action of nitrofurans. All three 11-treated subcultures independently presented the same six SNPs, which suggests their non-random occurrence and likely causative relationship between compound action and possible resistance mechanism.

A polymerase chain reaction and enzyme linked immunosorbent assay based approach for diagnosis and differentiation between vaccinated and infected cattle with Mycobacterium bovis

BACKGROUND

In most African and Arabic countries tuberculosis (TB) causes great economic losses in bovine species and constitutes serious zoonotic problem. As the traditional diagnostic method delay the research because of low sensitivity and specificity, a rapid method of diagnosis is of outmost importance.

AIM

The study was designed to evaluate the two rapid diagnostic methods of TB in cattle, further to differentiate between infected and bacillus Calmette-Guerin (BCG) vaccinated animals.

MATERIALS AND METHODS

Intradermal tuberculin test was applied to 300 cattle. Of these cattle, 15 cattle were vaccinated from cattle negative to tuberculin test with BCG. Blood samples were taken for lymphocyte separation to apply polymerase chain reaction (PCR) upon and for serum preparation for the enzyme-linked immunosorbent assay (ELISA) application, this blood collected from 65 cattle classified into three groups, viz. positive tuberculin test (35 animals), negative tuberculin test (15 animals), and vaccinated cow with BCG (15 animals). From blood samples lymphocytes were separated and the isolated lymphocytes were subjected to PCR and serum for ELISA application. Blood samples, specimens from lymph nodes and specific tissues were taken for PCR and for cultivation and isolation of Mycobacterium bovis.

RESULTS AND CONCLUSIONS

The results of this study revealed that PCR can be used as rapid efficient and accurate diagnostic test in detection of ruminant TB. Moreover, cattle's ELISA reading showed higher sensitivity in positive tuberculin animals. However, the differentiations between vaccinated and infected animals not clear by using a single antigen only.

Interrogation of rabbit miRNAs and their isomiRs

Rabbit (Oryctolagus cuniculus) is the only lagomorph animal of which the genome has been sequenced. Establishing a rabbit miRNA resource will benefit subsequent functional genomic studies in mammals. We have generated small RNA sequence reads with SOLiD and Solexa platforms to identify rabbit miRNAs, where we identified 464 pre-miRNAs and 886 mature miRNAs. The brain and heart miRNA libraries were used for further in-depth analysis of isomiR distributions. There are several intriguing findings. First, several rabbit pre-miRNAs form highly conserved clusters. Second, there is a preference in selecting one strand as mature miRNA, resulting in an arm selection preference. Third, we analyzed the isomiR expression and validated the expression of isomiR types in different rabbit tissues. Moreover, we further performed additional small RNA libraries and defined miRNAs differentially expressed between brain and heart. We conclude also that isomiR distribution profiles could vary between brain and heart tissues.

Application of the Enfer chemiluminescent multiplex ELISA system for the detection of Mycobacterium bovis infection in goats

A study was conducted to optimise a multiplex serological immunoassay for use in identification of goats infected with Mycobacterium bovis. To assess assay specificity, 31 goats with a history of being free from M. bovis infection were used. To determine assay sensitivity, 180 Single Intradermal Comparative Tuberculin test (SICTT) positive goats were recruited. Additionally, 286 SICTT negative goats classed as potentially exposed animals present in the same positive herds were also included in the study. The results of the assay demonstrated a specificity of 100%. The multiplex assay detected 57/60 SICTT (95.0%) positive animals in one M. bovis infected herd and 120/120 (100%) in a second herd. In a separate experiment, 28 M. caprae culture confirmed infected goats from Spain were assayed, of which 24 (85.7%) were found positive in the test. The results show that inclusion of an antibody based assay can improve the ability to identify M. bovis and M. caprae infected goats. With further development and validation the multiplex assay may prove to be a useful tool for control of M. bovis and M. caprae infection in goats.