Experiences with Mycobacterium leprae soluble antigens in a leprosy endemic population

Rees and Convit antigens prepared from armadillo-derived Mycobacterium leprae were used for skin testing in two leprosy endemic villages to understand their use in the epidemiology of leprosy. In all, 2602 individuals comprising 202 patients with leprosy detected in a prevalence survey, 476 household contacts and 1924 persons residing in non-case households were tested with two antigens. There was a strong and positive correlation (r = 0.85) between reactions to the Rees and Convit antigens. The distribution of reactions was bimodal and considering reactions of 12 mm or more as 'positive', the positivity rate steeply increased with the increase in age. However, the distributions of reactions to these antigens in patients with leprosy, their household contacts and persons living in non-case households were very similar. These results indicate that Rees and Convit antigens are not useful in the identification of M. leprae infection or in the confirmation of leprosy diagnosis in a leprosy endemic population with a high prevalence of nonspecific sensitivity.     

云贵川三省麻风菌株基因分型的比较研究

目的:了解云南、四川、贵州三省麻风菌株基因型的地理分布。方法:从云南省丘北县、四川省凉山州、贵州省兴义市分别采集59、21、31例麻风患者皮损活检,提取麻风菌DNA,对6-7、AC9、GTA9 3个数目可变的串联重复(variable-number tandem repeat,VNTR)位点的PCR产物测序,确定各位点重复序列数进行分型。结果:三省在6-7位点上有5种基因型,云南以7个拷贝的基因型为主,其它两地区的菌株在该位点的等位基因型为7、8、9,其分布无显著性差异。AC9位点上有4种基因型,三省均以8个拷贝的基因型为主。GTA9位点有非常明显的多样性。云南GTA9为9个拷贝的菌株占总菌株数的18.18%。结论:本研究结果提示麻风菌的基因型与地理分布有关。但需要以更多的位点,了解以VNTR为主的基因分型能否应用于麻风病的传染源和传播链的流行病学研究。     

Classic Kaposi's sarcoma in a Nepalese woman from a purportedly nonendemic area

Kaposis sarcoma (KS) occurs as four types; classic, endemic, immunosuppression-associated, and AIDS-associated. The presence of KS-associated herpesvirus (human herpesvirus 8) DNA in the tissue samples of 95% of all variants of KS has confirmed its role in the aetiopathogenesis of KS. It is now believed that these clinical variants most likely represent different manifestations of the same pathological process. Our case represents the first case of classic KS from our region.     

Presence of mycobactin-like substance in Mycobacterium leprae

Chloroform extracts of M. leprae suspensions--crude, partially purified and purified--were prepared by standard methods. Similar extracts were also prepared from the livers of normal armadillos using the same methods that were used to prepare crude and partially purified M. leprae suspensions. The only chloroform extract that supported the growth of M. paratuberculosis was the one prepared from Percoll gradient-purified M. leprae. Other four extracts not only did not support the growth of mycobactin-dependent M. paratuberculosis, but also inhibited the growth of mycobactin-independent strain of M. paratuberculosis. These results suggest the presence of mycobactin-like substance in M. leprae, and also, the presence of other unknown substance(s) in the crude suspensions of armadillo livers that inhibits the growth of M. paratuberculosis.     

Trophic changes and extensive dissemination in normal mice infected with human Mycobacterium leprae

Closely bred Swiss albino normal mice (Lecca Strain) were inoculated in the footpad with M. leprae, at room temperature. The animals were harvested at 3, 6 and 9 months post inoculation, and bacillary counts were made. Trophic changes were observed in the tail-tips, ears, footpads and forepaws 12-14 months post inoculation in a group which was allowed to survive. The histopathological changes and bacillary infiltration was found in many tissues/organs. The possibility of studying this normal strain of mice as an experimental model for human leprosy has been discussed.     

MDT治疗期间麻风菌VNTR位点的稳定性

目的: 评价MDT化疗前和皮肤组织液中麻风菌VNTR位点的稳定性.方法: 分别从12例MB新发患者的皮损组织、皮肤切刮组织液中提取麻风菌DNA.4例患者的DNA标本采用多重PCR扩增17个VNTR位点,8例患者扩增5个VNTR位点,同时常规PCR扩增2个VNTR位点.经直接测序确定VNTR位点重复拷贝数,用Genemapper软件进行片段长度分析.结果: 4例患者的皮损和组织液DNA标本的17个VNTR位点,不仅在MDT治疗前,等位基因型,即拷贝数没有差异,而且治疗期间每2个月连续取材的DNA标本的17个位点也高度相似.另8例患者,4例患者的麻风菌在这5个VNTR位点上无等位基因的变化.结论: 药物治疗对VNTR位点的稳定性无大影响,可能由于MDT后大部分麻风菌停止繁殖,DNA终止复制.     

Electron microscopy of Mycobacterium leprae in cutaneous nerve components

Cutaneous nerves in lepromatous lesions from ninety-six patients were observed by electron microscopy. The regenerative process of myelinated fibers was evident within lepromatous tissues. Intact or degenerative forms of Mycobacterium leprae were surrounded by the electron transparent substance within the axoplasm and Schwann cell cytoplasm. In contrast, the microenvironment of M. leprae in macrophages was characterized with fusing lysosomes and foamy structures. These results suggest that the electron transparent substance may be derived from bacterial metabolites and also that the foamy structure may originate from lysosomal substance.