Antigenic relationship between Mycobacterium paratuberculosis and Mycobacterium avium

Four prototype strains of Mycobacterium paratuberculosis contained the type-specific glycopeptidolipid antigen of serovar 8 of the M avium complex. This glycolipid was distinguished by a 4,6-(1'-carboxyethylidene)-3-O-methyl-beta-D-glucopyranosyl terminal unit. Of 59 low-passage, field isolates of M paratuberculosis, 2 contained this antigen, and these 2 isolates were indistinguishable from M avium serovar 8. However, most M paratuberculosis isolates had no characteristic surface glycopeptidolipid. Seemingly, M paratuberculosis, long regarded as a single species and the causative agent of bovine paratuberculosis, is not a homogeneous taxon. Most isolates obtained from infected ruminants may be antigenically defective, variants of M avium and, thereby, more successful pathogens.     

The GroES antigens of Mycobacterium avium and Mycobacterium paratuberculosis.

The GroES antigen provokes a strong immune response in human beings with tuberculosis or leprosy. We cloned and sequenced the Mycobacterium avium and Mycobacterium paratuberculosis GroES genes. M. avium and M. paratuberculosis have identical GroES sequences which differ from other mycobacterial species. This supports the current formal designation of M. paratuberculosis as M. avium subsp. paratuberculosis. Immunodominant epitopes from Mycobacterium tuberculosis GroES are conserved in M. avium, but some Mycobacterium leprae epitopes are distinct. GroES is unlikely to be specific as a serologic or skin test reagent, but may be an appropriate component of a broad mycobacterial vaccine.     

Spoligotype diversity of Mycobacterium bovis and Mycobacterium caprae animal isolates

The genetic diversity of 283 Mycobacterium bovis (M. bovis) and 10 Mycobacterium caprae (M. caprae) strains, isolated between 2002 and 2007 from cattle, goat, red deer and wild boar from six different geographical regions of Portugal was investigated by spoligotyping. The technique showed a good discriminatory power (Hunter-Gaston Index, h=0.9) for the strains, revealing 29 different patterns. One pattern (SB0121) was clearly predominant, accounting for 26.3% of the isolates; ten patterns, representing 20.7% of the isolates, had never been reported previously. Multiple spoligotypes were detected in thirteen cattle and one goat herd, most of which were found in beef cattle and extensive management regions, suggesting different infection sources. With the exception of two spoligotypes, those in wildlife species were also found in domestic species.     

Tuberculosis due to Mycobacterium bovis and Mycobacterium caprae in sheep

Tuberculosis was diagnosed in three flocks of sheep in Galicia, Spain, in 2009 and 2010. Two flocks were infected with Mycobacterium bovis and one flock was infected with Mycobacterium caprae. Infection was confirmed by the comparative intradermal tuberculin test, bacteriology, molecular analysis and histopathology. Sheep have the potential to act as a reservoir for tuberculosis.     

Zoonotic aspects of Mycobacterium bovis and Mycobacterium avium-intracellulare complex (MAC)

Pathogens that are transmitted between the environment, wildlife, livestock and humans represent major challenges for the protection of human and domestic animal health, the economic sustainability of agriculture, and the conservation of wildlife. Among such pathogens, the genus Mycobacterium is well represented by M. bovis, the etiological agent of bovine tuberculosis, M. avium ssp. paratuberculosis (Map) the etiological agent of Johne disease, M. avium ssp. avium (Maa) and in a few common cases by other emergent environmental mycobacteria. Epidemiologic surveys performed in Europe, North America and New Zealand have demonstrated the existence and importance of environmental and wildlife reservoirs of mycobacterial infections that limit the attempts of disease control programmes. The aim of this review is to examine the zoonotic aspects of mycobacteria transmitted from the environment and wildlife. This work is focused on the species of two main groups of mycobacteria classified as important pathogens for humans and animals: first, M. bovis, the causative agent of bovine tuberculosis, which belongs to the M. tuberculosis complex and has a broad host range including wildlife, captive wildlife, domestic livestock, non-human primates and humans; the second group examined, is the M. avium-intracellulare complex (MAC) which includes M. avium ssp. avium causing major health problems in AIDS patients and M. avium ssp. paratuberculosis the etiological agent of Johne disease in cattle and identified in patients with Crohn disease. MAC agents, in addition to a broad host range, are environmental mycobacteria found in numerous biotopes including the soil, water, aerosols, protozoa, deep litter and fresh tropical vegetation. This review examines the possible reservoirs of these pathogens in the environment and in wildlife, their role as sources of infection in humans and animals and their health impact on humans. The possibilities of control and management programmes for these mycobacterial infections are examined with regards to the importance of their natural reservoirs.     

Pathogenicity of Mycobacterium fortuitum and Mycobacterium smegmatis to goldfish, Carassius auratus

Despite the ubiquitous presence of atypical mycobacteria in the environment and the potential risk of infection in humans and animals, the pathogenesis of diseases caused by infection with atypical mycobacteria has been poorly characterized. In this study, goldfish, Carassius auratus were infected either with the rapidly growing fish pathogen, Mycobacterium fortuitum or with another rapidly growing mycobacteria, Mycobacterium smegmatis. Bacterial persistence and pathological host response to mycobacterial infection in the goldfish are described. Mycobacteria were recovered from a high percentage of inoculated fish that developed a characteristic chronic granulomatous response similar to that associated with natural mycobacterial infection. Both M. fortuitum and M. smegmatis were pathogenic to fish. Fish infected with M. smegmatis ATCC 19420 showed the highest level of giant cell recruitment compared to fish inoculated with M. smegmatis mc(2)155 and M. fortuitum. Of the three strains of mycobacteria examined, M. smegmatis ATCC 19420 was the most virulent strain to goldfish followed by M. fortuitum and M. smegmatis mc(2)155, respectively.     

Expression and Bioactivity Identification of eis Gene of Mycobacterium bovis in Mycobacterium smegmatis

This study was aimed to construct a shuttle expression vector of Mycobacterium bovis(M.bovis) eis gene and identify its bioactivity in recombinant Mycobacterium smegmatis (M.smegmatis). M.bovis eis gene was cloned by PCR and the shuttle expression vector pMV261-Mbeis was constructed, then it was identified by double digestion and sequencing. The recombinant plasmid was transformed into M.smegmatis mc²155 by electroporation. The expression of M.bovis eis gene in M.smegmatis was detected by SDS-PAGE and Western blotting, and the amino acids sequence of the target protein was identified by mass spectrometry. The growth curve of recombinant M.smegmatis mc²155 containing pMV261-Mbeis was successfully constructed.The results showed that pMV261-Mbeis did not affect the growth of M. smegmatis in vitro. The results of SDS-PAGE and Western blotting confirmed that the M. bovis eis gene expressed the eis protein which was about 44 ku in M. smegmatis. Mass spectrometry proved that the protein was the eis protein of M. bovis.The expression vector pMV261-Mbeis was successfully constructed and the expressed recombinant protein was proved to be have biological activities in M. smegmatis, which laid a foundation for the further study of the function of eis protein in M. bovis.     

结核分枝杆菌rv0199基因在耻垢分枝杆菌中的表达及检测

为研究结核分枝杆菌（M.tb）rv0199基因在该病原致病性中可能发挥的作用,本研究克隆了rv0199基因,在耻垢分枝杆菌（Ms）中异源表达,并对其表达进行检测。将大肠杆菌-分枝杆菌穿梭表达载体pMV261进行改造,向载体中引入常用的6His和Strep Ⅱ重组蛋白标签,命名为pMV262。使用Ms/pMV262表达系统对rv0199基因进行超表达,用抗6His标签抗体和抗Strep Ⅱ标签抗体均能特异的检测到重组蛋白。本试验改造的pMV262穿梭表达载体可很方便的检测M.tb的基因在Ms中的异源表达,不用制备针对蛋白的多克隆抗体或单克隆抗体。构建的重组菌Ms/262-99为进一步研究rv0199基因的功能提供了材料,奠定了基础。     

Mycobacterium paratuberculosis and milk

The possibility that milk from cattle with Johne's disease could be a potential vehicle of transmission of Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) to humans has been the focus of a UK government-funded research programme at Queen's University, Belfast since 1993. The main findings of this research programme are reported and practical advice about the most appropriate methods for the isolation/detection of this organism in milk is given. The findings of several milk surveys during which optimised sensitive detection methods were employed (decontamination with 0.75% cetyl pyridinium chloride for 5 h prior to culture and a novel immunomagnetic PCR technique) have revealed that detectable levels of M. paratuberculosis are present in bulked raw cows' milk in the UK at both the farm level and at dairy processing plants prior to pasteurisation. Furthermore, results of three different experimental approaches to assess the effect of pasteurisation time/temperature conditions on the viability of M. paratuberculosis (laboratory pasteurisation studies, a national survey of commercially pasteurised milk, and processing of naturally infected milk through commercial-scale pasteurising plant) provide firm evidence that this organism is capable of surviving commercial milk pasteurisation on occasion. Hence, both raw and pasteurised cows' milk are potential vehicles of transmission of M. paratuberculosis to humans.     

Carboxyl terminus of the 34 kDa protein of Mycobacterium paratuberculosis shares homologous B-cell epitopes with Mycobacterium avium and Mycobacterium intracellulare

Monoclonal antibodies (mAbs) against a recombinant carboxyl terminus of the 34 kDa protein of Mycobacterium paratuberculosis were produced in mice. Two of the mAbs cross-reacted with Mycobacterium avium and Mycobacterium intracellulare in both an elisa and immunoblot. The recombinant protein also reacted with polyclonal sera produced in rabbits against all three mycobacteria, indicating the presence of cross-reactive epitopes in the protein. To determine the reactivity of cattle sera against epitopes recognised by the mAbs, competition assays between bovine sera and the mAbs were carried out. Two mAbs were significantly inhibited by sera from cattle that were naturally infected with M paratuberculosis. The results indicate that epitopes on the carboxyl terminus of the 34 kDa protein common to M paratuberculosis, M avium and M intracellulare readily induce antibody production in naturally infected cattle. These epitopes reduce the diagnostic specificity of the carboxyl terminus of the 34 kDa protein, which was originally thought to contain only M paratuberculosis-specific epitopes.     

牛分枝杆菌eis基因在耻垢分枝杆菌中的表达及其生物学活性鉴定

试验旨在构建牛分枝杆菌eis基因的穿梭表达载体,鉴定其在重组耻垢分枝杆菌中的生物学活性。采用PCR技术扩增并克隆牛分枝杆菌eis基因,构建大肠杆菌-分枝杆菌穿梭表达载体pMV261-Mbeis,经双酶切和测序鉴定其正确性,利用电穿孔法将重组质粒转化至耻垢分枝杆菌mc²155中,采用SDS-PAGE和Western blotting技术检测牛分枝杆菌eis基因在耻垢分枝杆菌中的表达,质谱鉴定目的蛋白氨基酸序列。研究结果表明,成功构建了牛分枝杆菌eis基因穿梭表达载体pMV261-Mbeis;生长曲线表明负载重组质粒不会影响耻垢分枝杆菌的体外生长;SDS-PAGE和Western blotting检测证实了牛分枝杆菌eis基因在耻垢分枝杆菌中可表达出分子质量约44 ku的eis蛋白;质谱检测证明了该蛋白即为牛分枝杆菌eis蛋白。本研究构建的牛分枝杆菌eis基因穿梭表达质粒pMV261-Mbeis在耻垢分枝杆菌中具有生物学活性,为下一步研究表达产物eis蛋白的功能奠定了基础。     

结核分枝杆菌与牛分枝杆菌全基因组比较分析

本研究旨在揭示结核分枝杆菌与牛分枝杆菌全基因组的遗传差异,为结核分枝杆菌与牛分枝杆菌的鉴别诊断提供新的分子标志。利用结核分枝杆菌H37Rv和牛分枝杆菌AF2122/97的全基因组测序结果,通过在线比对,完成了两者的全基因组比对分析。结果显示AF2122/97相对H37Rv存在14处大片段缺失,大小范围为0.8～12.7kb,其中RD18、RD19及RD20等3处缺失为首次报道。此外,AF2122/97还存在6处基因内部小片段的缺失,大小范围为12～714bp,其中Mb1319及Mb3293c基因内部缺失为首次报道。H37Rv相对AF2122/97存在6处大片段缺失,大小范围为1.3～5.4kb。此外,H37Rv还存在5处基因内部小片段的缺失,大小范围为10～48bp,这些基因的内部缺失都为首次报道。通过结核分枝杆菌H37Rv和牛分枝杆菌AF2122/97的全基因组序列比对,揭示了这2种菌株间的遗传差异,阐述影响表型特征、寄主偏好性及毒力差异的关键性遗传基础。这些新的认识将有助于开发新的药物、诊断试剂和疫苗。     

牛分枝杆菌PE_PGRS62基因克隆及在耻垢分枝杆菌中的表达

为构建表达牛分枝杆菌(M.bovis)PE_PGRS62蛋白的重组耻垢分枝杆菌,本研究以M.bovis基因组DNA为模板PCR扩增PE_PGRS62基因,获得大小约为1 515 bp的目的片段,并克隆到大肠杆菌-分枝杆菌穿梭表达载体pMV261中,将重组pMV-PE_PGRS62穿梭表达载体电转化到耻垢分枝杆菌内,42℃热诱导重组耻垢分枝杆菌,通过SDS-PAGE和免疫印迹分析表达产物并鉴定其生物学活性。经SDS-PAGE分析,表达的PE_PGRS62蛋白分子量约为60 ku,免疫印迹结果表明,表达的PE_PGRS62蛋白与兔抗M.bovis阳性血清反应形成一条特异性蛋白条带。本实验为进一步研究M.bovis致病机理奠定了基础。     

Molecular epidemiology of Mycobacterium avium subsp. avium and Mycobacterium intracellulare in captive birds

Mycobacterium avium subsp. avium and Mycobacterium intracellulare are primary causes of mycobacteriosis in captive birds throughout the world, but little is known about how they are transmitted. To define the local epidemiology of infection, we strain-typed 70 M. avium subsp. avium and 15 M. intracellulare culture isolates obtained over a 4-year period from captive birds. Typing was performed using randomly amplified polymorphic DNA (RAPD) PCR, amplified fragment length polymorphic (AFLP) fragment analyses, and for a subset of isolates, DNA sequencing of a segment of the 16S-23S rRNA internal transcribed spacer region. Six strain clusters comprising 43 M. avium subsp. avium, isolates were identified; 42 isolates had unique typing patterns, including all M. intracellulare isolates. Phylo-geographical analyses using RAPD and AFLP fingerprints and animal confinement histories showed no correlation between housing of infected birds and mycobacterial strain-type, except for two animals. The diversity of M. avium subsp. avium and M. intracellulare isolates and minimal evidence for bird-to-bird transmission suggest that environmental reservoirs may be important sources of infection in captivity.     

Gas chromatographic characterization of the relationship between some Mycobacterium avium and Mycobacterium paratuberculosis strains

Mycobacterium avium strain P-55 and M. avium strain DENT differ from M. avium strain 16909-338 on the basis of their fatty acid spectra (C14:0, C18:0 and tuberculostearic [TBS] acids) studied by multivariate statistical analyses. Strains P-55 and DENT are closer to M. paratuberculosis strain 5889 than to M. avium strain 16909-338, a finding which is in harmony with earlier immunological observations. The recently isolated M. paratuberculosis strain 385 has proved different from M. paratuberculosis strain 5889.     

HPLC does not differentiate Mycobacterium paratuberculosis from Mycobacterium avium

HPLC, which is gaining its place as identification tool in mycobacteriology laboratories, has been proposed to distinguish Mycobacterium paratuberculosis from Mycobacterium avium. We had reported no significant difference between M. avium and M. paratuberculosis reference strain ATCC 19698. Because of the advantages offered by such a method, we enlarged our observations to include more isolates of M. paratuberculosis. Within the double cluster of peaks obtained by both M. avium and M. paratuberculosis, we could not find a consistent difference typical of M. paratuberculosis. Therefore, the present study confirmed that M. avium and M. paratuberculosis could not be distinguished by HPLC, raising doubts of a straightforward use of HPLC to identify M. paratuberculosis.     

The epizootiological significance of positive bacteriological findings on Mycobacterium tuberculosis and Mycobacterium bovis in humans

The relation between the active form of tuberculosis in persons working in agriculture and incidence of tuberculosis in cattle was analyzed in 1974 to 1978, i.e. in the period after the elimination of bovine tuberculosis in Czechoslovakia (in 1968). M. tuberculosis was isolated in 15 cases and M. bovis in four cases of persons employed by the farms on which the Regional Hygienic Station, Brno, was responsible for the microbiological diagnostics of tuberculosis. Direct contact with animals was demonstrated in eight patients; M. tuberculosis was isolated from seven of these patients and M. bovis from one. Seven cattle herds were exposed to spontaneous infection by M. tuberculosis and in one of them tuberculosis was not demonstrated during complex examination. In three herds the examination revealed only a sensitivity of cattle to mammalian tuberculin. In other three herds tuberculosis was detected by allergic tests, patho-anatomic examination and bacteriological examination. M. tuberculosis in cattle was detected in two herds. The occurrence of bovine tuberculosis caused by a cattle tender with a positive finding of M. bovis in sputum was demonstrated in one herd. Virulence for the tested cattle was found in one strain (isolated from a mesenterial lymph node of cattle) of the four strains of M. tuberculosis used for the experimental infection of 17 animals. On the other hand, in three strains of M. tuberculosis, trials with experimental infection demonstrated only allergy to mammalian tuberculin and changes at the sites of subcutaneous inoculation of mycobacteria of regressive nature; these mostly disappeared within 90 days from infection.