Antigenic characteristics and stability of microencapsulated Mycoplasma hyopneumoniae vaccine

The in vitro stability (temperature, pH, and trypsin) of Mycoplasma hyopneumoniae antigen (MHA) with and without enteric-coated microencapsulation were examined. Microencapsulation of MHA with cellulose acetate phthalate (CAP) is an effective route to produce enteric-coated vaccine microspheres for oral administration. The effect of temperature on the rate of inactivation of MHA was studied by exposing MHA to various temperatures, such as 25, 37, 50 and 60 degrees C. The MHA microspheres were thermally more stable than that of the unencapsulated MHA. The kinetic parameters were observed to follow an Arrhenius-type temperature dependence. The MHA microspheres were also more stable in acidic regions (pH 1.2-4.0) than that of the free one. The enteric-coated MHA microspheres exhibited an excellent enteric function to prevent acidic degradation. A model similar to the well-known Michaelis-Menten equation was formulated to describe the effect of trypsin on the antigenic degradation of MHA. The equilibrium constant K(A) and the maximum reaction velocity V(m) were obtained from experimental data for both free and microencapsulated MHA. Both K(A) and V(m) values of the microencapsulated MHA were smaller than that of the free one, i.e., the resistance to proteolytic enzyme such as trypsin was enhanced by microencapsulation. The storage stability of enteric-coated MHA microspheres has been satisfactorily prolonged that they could preserve more than 90% of original antigenicity after 30 days, and over 80% of antigenicity of MHA was retained in the microspheres for 95 days when it was stored at 4 degrees C.     

Physical mapping of the Mycoplasma capricolum genome

A physical map of Mycoplasma capricolum ATCC 27343 genome was constructed, based on estimation of the restriction fragment sizes by pulse-field electrophoresis. The linkage order of restriction fragments was determined by two-dimensional electrophoresis of partial and complete single digests and complete double digests and by Southern hybridization analysis. The genome size was established at 1155.5 kb, and 26 cleavage sites for 7 endonucleases were assigned to the map.     

北京市铁路地区部分女性生殖道支原体感染状况的调查

本文报告了1990年5月对北京市92名性乱者女性和129名健康妇女进行解脲和人型支原体分离培养结果。前者的检出率为71.74％,后者为19.57％,两者同时检出为18.48％,而健康妇女其检出率则分别为43.41％、5.43％和4.65％。说明性乱妇女支原体感染率以显著高于健康妇女。提示北京地区存在支原体性病,这对进一步掌握我国性病病谱提供了新的资料。     

女性激素状态与生殖道支原体寄居的关系

本文调查了959名不同性激素状态妇女生殖道溶脲支原体(Uu)和人型支原体(Mh)的寄居情况。结果表明新生女婴、产后妇女和绝经妇女Uu和Mh寄居率较低,妊娠妇女Uu和Mh寄居率则相当高;已婚非孕妇女Uu和Mh寄居率高于未婚者。提示了女性激素水平与生殖道支原体寄居状态有密切联系。     

Two cholesterol pools in Acholeplasma laidlawii membranes

Cholesterol exchange kinetics between [14C]cholesterol-labeled Acholeplasma laidlawii and Mycoplasma gallisepticum cells and phosphatidylcholine-cholesterol vesicles followed a biphasic curve, with faster exchange rates for A. laidlawii. The same biphasic curve was obtained with isolated membranes. Cholesterol exchange between lipid vesicles and A. laidlawii cells depleted of phospholipids by phospholipase A2, fitted a monophasic linear curve. The data support the hypothesis that the biphasic cholesterol exchange kinetics do not result from the transbilayer distribution of cholesterol, but reflect the presence in the membrane of two cholesterol pools associated with lipids of high and low affinity for cholesterol.     

Elongation factor (EF-Tu) gene probe detects polymorphism in Mycoplasma strains

Abstract Polymorphism in mycoplasma strains was observed by Southern blot hybridization of the digested mycoplasma DNAs with the elongation factor (EF-Tu) gene tuf of Escherichia coli . The hybridization patterns revealed genotypic heterogeneity among Mycoplasma gallisepticum strains and a remarkable degree of homogeneity among Mucoplasma pneumoniae strains isolated from pneumonia patients. The distinction among M. gallisepticum strain clusters achieved by the tuf gene probe corresponded exactly with that obtained with the rRNA gene probe pMC5. The tuf gene probe may thus be added as another effective tool in the taxonomy of Mollicutes and in epidemiological surveys of mycoplasma infections.     

MDHM, a macrophage-activating product of Mycoplasma fermentans, stimulates murine macrophages to synthesize nitric oxide and become tumoricidal

Abstract In continuation of previous work on macrophage activation by a Mycoplasma fermentans -derived product, originally named “mycoplasma-derived high mol. wt. material” (MDHM), we have investigated whether MDHM was capable of inducing synthesis of the reactive nitrogen intermediate nitric oxide (NO), thus rendering macrophages cytocidal. Mycoplasmas were first delipidated with acetone, and MDHM activity was then extracted with 50 mM 1-O-octyl-β- d -glucopyranoside to yield a particularly active new preparation of MDHM which we have named MDHM-D (D for detergent). In combination with IFN-γ, MDHM-D activated macrophages to produce reactive nitrogen intermediates and kill P815 mastocytoma cells in co-culture. P815 target cells were chosen because they are TNF-resistant. Macrophages from the LPS-low responder strain C3H/HeJ were used to minimize interference from possible LPS contamination. MDHM-D activity in this system was strictly IFN-γ-dependent. In the presence of 25 U/ml IFN-γ MDHM-D gave a half maximal response at a dilution of 1/100 000, showing a parallel concentration dependency for nitrite production and cytocidal activity.     

Homology modeling of Mycoplasma pneumoniae enolase and its molecular interaction with human plasminogen

Alpha (α)-enolase (e), a glycolytic enzyme, has an alternative role as a surface receptor of several bacteria mediating plasminogen (pg) binding. It is also recognized as a virulence factor of some pathogenic bacteria facilitating plasminogen activation and host cell invasion. A mycoplasmal α-enolase is also a plasminogen binding protein. Molecular interactions of enolase from Mycoplasma pneumoniae with host plasminogen would be useful for exploring the pathogen-host interaction. In an attempt to identify plasminogen binding sites of M. pneumoniae enolase, homology modeling and docking studies were conducted to obtain modeled structures of the M. pneumoniae enolase-plasminogen complex. The refined model was validated further by standard methods. Molecular docking revealed hydrogen bonding of eLys70-pgTyr50, eAsn165-pgThr66, eAla168-pgGlu21, eAsp17-pgLys70, and eAsn213-pgPro68/pgAsn69. Substantial decreases in accessible surface area (ASA) were observed and in concurrence with hydrogen bond pattern. These findings provide a detailed prediction of key residues that interact at the protein-protein interface. Our theoretical prediction is consistent with known biochemical data. The predicted interaction complex can be of great assistance in understanding structural insights, which is necessary to pathogen and host-component interaction. The ability of M. pneumoniae enolase to bind plasminogen may be indicative of an important role in invasion of this pathogen to host.     

Disease and secondary sexual traits: effects of pneumonia on horn size of bighorn sheep

Secondary sexual traits (e.g., horns and antlers) have ecological and evolutionary importance and are of management interest for game species. Yet, how these traits respond to emerging threats like infectious disease remains underexplored. Infectious pneumonia threatens bighorn sheep (Ovis canadensis) populations across North America and we hypothesized it may also reduce horn growth in male sheep. We assess the effect of pneumonia on horn size in male bighorn sheep using 12 herd datasets from across the western United States that had horn growth and disease data. Disease resulted in 12–35% reduction in increment (yearly) length and 3–13% reduction in total horn length in exposed individuals. The disease effect was prolonged when pathogens continued to circulate in sheep populations. Further, disease likely delays the age at which horns reach ¾-curl and prevents achievement of full-curl. This is further evidenced with 6 of the 12 herds experiencing an increase in average age at harvest following die-off events.     

儿童副流感病毒、肺炎支原体感染情况研究

摘要 目的：通过检测及分析住院患儿血清中副流感病毒、肺炎支原体IgM抗体,探讨两种病原体感染的流行病学特征。方法：应用酶联免疫分析的方法定性检测患儿血清中的副流感病毒、肺炎支原体IgM抗体,采用卡方检验对不同年份、性别、年龄及季节的数据进行分析。结果：副流感病毒、肺炎支原体阳性率分别为3.6%、22.4%,混合感染的阳性率为1.3%。PIV每年女性患儿比男性患儿阳性率高,每一年中6-14岁感染阳性率最高;MP每年女性患儿比男性患儿阳性率高,随着年龄增长感染的阳性率也升高,6-14岁阳性率最高。PIV与MP在每年的四季中,感染的阳性率各不相同,并且没有相对的规律可循,但是在冬季阳性率还是较高,其次是春季、秋季,最低的是夏季。结论：掌握儿童副流感病毒和肺炎支原体感染流行病学特点,有助于了解疾病感染特点,从而在疾病的不同时期及时快速地采取相应措施。