Dataset Information

Identification of a polymorphic nucleotide in oxyR specific for Mycobacterium bovis.

ABSTRACT: Automated sequence analysis of a 410-bp region of the axyR gene in 105 Mycobacterium tuberculosis complex isolates identified a polymorphic nucleotide that differentiated Mycobacterium bovis isolates from other complex members. All 29 M. bovis isolates sequenced had an adenine residue at nucleotide 285, whereas all 76 other complex isolates had a guanine residue. PCR-restriction fragment length polymorphism analysis of oxyR with restriction endonuclease AluI in an additional 255 complex isolates from widespread intercontinental sources confirmed and extended the unique association of adenine at position 285 with M. bovis isolates.

SUBMITTER: Sreevatsan S

PROVIDER: S-EPMC229172 | biostudies-other | 1996 Aug

REPOSITORIES: biostudies-other

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Identification of a polymorphic nucleotide in oxyR specific for Mycobacterium bovis.

Sreevatsan S S Escalante P P Pan X X Gillies D A DA Siddiqui S S Khalaf C N CN Kreiswirth B N BN Bifani P P Adams L G LG Ficht T T Perumaalla V S VS Cave M D MD van Embden J D JD Musser J M JM

Journal of clinical microbiology 19960801 8

Automated sequence analysis of a 410-bp region of the axyR gene in 105 Mycobacterium tuberculosis complex isolates identified a polymorphic nucleotide that differentiated Mycobacterium bovis isolates from other complex members. All 29 M. bovis isolates sequenced had an adenine residue at nucleotide 285, whereas all 76 other complex isolates had a guanine residue. PCR-restriction fragment length polymorphism analysis of oxyR with restriction endonuclease AluI in an additional 255 complex isolates ...[more]

PMID: 8818900

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Project description:Bovine tuberculosis (bTB) is a chronic disease mainly caused by Mycobacterium bovis, a zoonotic pathogen with economic significance as it leads to reduced milk and meat production, and high costs for control measures. The Bacillus Calmette-Guérin (BCG) vaccine, primarily used to prevent tuberculosis in humans, has also been studied for controlling bTB. While showing effectiveness in preventing M. bovis infection and disease in cattle, the BCG vaccine can induce non-specific effects on the immune system, enhancing responses to infections caused by unrelated pathogens, and also having non-specific effects on lactation. The aim of this study is to describe both the specific and non-specific effects of BCG vaccination in calves from a commercial dairy herd in central Chile. Diagnosis of M. bovis infection was performed through the IFNγ release assay (IGRA) using ESAT6/CFP-10 and Rv3615c antigens. The records of milk production, somatic cell count (SCC), clinical mastitis (CM) and retained placenta (RP) during the first lactation were compared between vaccinated and non-vaccinated animals. The breed (Holstein Friesian [HF] v/s HF × Swedish Red crossbred [HFSR]) and the season (warm v/s cold) were also analyzed as categorical explanatory variables. Results of IGRA showed significant differences between vaccinated and control groups, indicating a vaccine efficacy of 58.5% at 18 months post vaccination in HFSR crossbred animals. Although milk production did not vary, SCC and CM showed differences between groups, associated to the breed and the season, respectively. When analyzing CM and RP as a whole entity of disease, BCG showed protection in all but the cold season variables. Overall, the BCG vaccine induced protective specific and non-specific effects on health parameters, which may be influenced by the breed of animals and the season. These results provide new features of BCG protection, supporting initiatives for its implementation as a complementary tool in bTB control.

Project description:In contrast to the intact oxyR gene (a homolog of the central regulator of peroxide stress response in enteric bacteria) in Mycobacterium leprae, this gene is inactive in all strains of M. tuberculosis. In both species, oxyR is divergently transcribed from ahpC, which encodes a homolog of alkyl hydroperoxide reductase. To initiate investigations of the regulation of oxidative stress in mycobacteria and consequences of the elimination of oxyR in M. tuberculosis, in this work we tested the hypothesis that mycobacterial OxyR acts as a DNA binding protein and analyzed its interactions with the oxyR and ahpC promoters. M. leprae OxyR was overproduced and purified, and its binding to the oxyR-ahpC intergenic region of M. leprae was demonstrated. By using a sequential series of overlapping DNA fragments, the minimal OxyR binding site was delimited to a 30-bp DNA segment which included a palindromic sequence conforming with the established rules for the LysR family of regulators. A consensus sequence for the mycobacterial OxyR recognition site (cTTATCggc-N3-gccGATAAg) was deduced based on its conservation in different mycobacteria. A variance in two potentially critical nucleotides within this site was observed in M. tuberculosis, in keeping with its reduced affinity for OxyR. Transcription of plasmid-borne M. leprae oxyR and ahpC was investigated in M. smegmatis and M. bovis BCG by S1 nuclease protection and transcriptional fusion analyses. Two mRNA 5' ends were detected in each direction: (i) P1oxyR and P2oxyR and (ii) P1ahpC and P2ahpC. The binding site for OxyR overlapped P1oxyR, reminiscent of the autoregulatory loops controlling expression of oxyR in enteric bacteria and characteristic of the LysR superfamily in general. This site was also centered 65 bp upstream of P1ahpC, matching the usual position of LysR-type recognition sequences in relationship to positively controlled promoters. Superimposed on these features was the less orthodox presence of multiple transcripts and their unique arrangement, including a region of complementarity at the 5' ends of the P2ahpC and P2oxyR mRNAs, suggesting the existence of complex regulatory relationships controlling oxyR and ahpC expression in mycobacteria.

Dataset Information

Identification of a polymorphic nucleotide in oxyR specific for Mycobacterium bovis.

Publications

Identification of a polymorphic nucleotide in oxyR specific for Mycobacterium bovis.

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