Modeling analysis revealed the distinct global transmission patterns of influenza A viruses and their influencing factors

Influenza A virus has caused huge damage to human health and poultry production worldwide, but its global transmission patterns and influencing factors remain unclear. Here, by using the Nearest Genetic Distance Approach with genetic sequences data, we reconstructed the global transmission patterns of 4 most common subtypes of influenza A virus (H1N1, H3N2, H5N1, and H7N9) and analyzed associations of transmission velocity of these influenza viruses with environmental factors. We found that the transmission patterns of influenza viruses and their associations with environmental factors were closely related to their host properties. H1N1 and H3N2, which are mainly held by humans, are transmitted between regions at high velocity and over long distances, which may be due to human transportation via airplane; while H5N1 and H7N9, which are mainly carried by animals, are transmitted locally at short distances and at low velocity, which may be facilitated by poultry transportation via railways or high ways. H1N1 and H3N2 spread faster in cold seasons, while H5N1 spread faster in both cold and warm seasons, and H7N9 spread faster in wet seasons. H1N1, H3N2, and H5N1 spread faster in places with both high and low human densities. Our study provided novel insights into the global transmission patterns, processes, and management strategies for influenza under accelerated global change.     

不同利用方式下羊草草原土壤生态系统微生物群落结构的PLFA分析

本研究利用磷脂脂肪酸(PLFA)法分析了不同利用方式对羊草草原土壤生态系统微生物群落结构的影响。结果表明,不同利用方式下羊草草原土壤微生物群落结构发生显著变化。刈割下表征土壤微生物的PLFA总量显著高于围封和放牧利用,围封条件下PLFA总量最低,相关分析表明,PLFA总量与土壤微生物量碳(熏蒸提取法)极显著正相关。刈割显著提高了土壤细菌含量,围封使土壤中放线菌含量显著增加,土壤中真菌含量在3种利用方式下则无显著变化。刈割样地表征细菌的PLFA量最高,为29.6 nmol/g,放牧和围封样地中细菌的含量分别比刈割样地降低了27.8%和49.3%。刈割样地的优势PLFA类型为a15:0,15:0,16:0和18:0,占PLFA总量的64.6%,放牧样地中优势PLFA类型为i15:0,i16:0和18:1ω9t,占PLFA总量的45.6%;围封样地中,优势PLFA类型为a15:0,15:0和i16:0,占PLFA总量的46.3%。     

Comparison of pulsed field gel electrophoresis and repetitive sequence polymerase chain reaction as genotyping methods for detection of genetic diversity and inferring transmission of Salmonella

Pulsed field gel electrophoresis (PFGE) using restriction enzymes AvrII, SpeI, and XbaI, and repetitive sequence polymerase chain reaction (Rep-PCR) using BOX, ERIC, and REP primers, were compared with respect to their ability to detect genetic differences among 68 Salmonella isolates from nine Illinois swine farms. Both genotyping methods had high reproducibility of fragment numbers (reliability>0.9) and sizes (reliability>0.85), and produced approximately the same number of DNA fragments, but Rep-PCR fragment profiles had considerably greater variation. Genetic distances between isolates were calculated from fragment size matching. There was good agreement between the genetic distance matrices for the composite (3-enzyme and 3-primer) methods (Mantel’s r=0.83). PFGE detected slightly greater variation in genetic distances among isolates, but failed to differentiate seven pairs of isolates, three of which were sampled at least 1 month apart and therefore unlikely to be truly identical genetically. In contrast, Rep-PCR identified no isolates as genetically identical. In cluster analyses based on genetic distances, there were moderate differences between PFGE and Rep-PCR (about 2/3 agreement in tight cluster membership). Both PFGE and Rep-PCR were able to differentiate isolates of the same serotype. However, some serotypes (Agona, Anatum, Derby, Infantis, Worthington) were distributed across clusters. There was less agreement between individual primer/enzyme and composite results for Rep-PCR than for PFGE. This greater independence of results for individual primers for Rep-PCR accounted in part for the greater discriminative ability of the composite method. Both composite methods indicated that most Salmonella transmission occurred within a farm and that there was no preference for transmission between specific ecological compartments. Given the equally high reliability of both genotyping methods, the greater discriminative ability of Rep-PCR recommends it as the preferred method for precise detection of transmission links.     

微生态制剂在反刍动物生产上的应用

微生态制剂又称益生素、活菌制剂等,它是在微生态理论指导下,通过特殊工艺应用已知有益微生物制成的一种活菌制剂,在养殖业已经得到应用。文章综述了微生态制剂的概念、分类、在反刍动物中的应用;剖析了不同实验结果出现差异的可能原因,总结了微生态制剂应用中存在的问题及应用前景展望。     

微生物植酸酶在水产饲料中的应用

国内外对于水产饲料中添加微生物植酸酶已有一些研究,并取得了明显的效果。1微生物植酸酶对鱼类的营养作用1.1提高磷及其他矿物元素的生物利用率 大量试验证明,日粮中添加微生物植酸酶可以提高磷的生物利用率。Vielma等(1998、2002)报道,在含有植物蛋白的日粮中添加微生物植酸酶可以增加虹鳟日增重,提高磷的生物利用率。另有报道,添加植酸酶可以提高欧洲海鲈对磷的利用率,增加大西洋鲑鱼蛋白质消化率和磷的生物利用率     

微生物发酵饲料在水产养殖中的应用

随着水产养殖业的高速发展,动物性蛋白源短缺和抗生素滥用等问题给水产行业的健康、可持续发展带来诸多挑战.近年来,相关研究表明,微生物发酵饲料具有利于转化传统植物蛋白源中的抗营养因子、提高饲料利用率、改善动物机体健康水平和免疫功能等作用.本文从国内外关于微生物发酵饲料在水产领域的应用现状及其对水产动物的有益作用方面进行了综...     

既有猪舍节能改造及能耗分析

我国北方寒地冬季采暖期长,猪舍围护结构简单,因而能耗过高,资源浪费,增加饲养成本。本文对吉林地区既有猪舍能耗量De ST模型分析后,提出2种节能改造方案,增加保温层方案和硅镁无机玻璃钢方案。经能耗分析,硅镁无机钢玻璃猪舍的性能更好,建议新建猪舍可借鉴此方案,减少建筑能耗,节约资源。     

Airway microbial culture and susceptibility patterns in dogs and cats with respiratory disease of varying severity

Objective – To compare airway microbiological culture and susceptibility results in 2 groups of dogs and cats: 1 with respiratory failure requiring positive pressure ventilation (PPV) and 1 with respiratory disease. Design – Retrospective study. Setting – University teaching hospital. Animals – Fifty‐two dogs and cats requiring PPV that had an airway microbiologic culture submitted from October 1, 2003 to October 31, 2008 were included. One hundred and four airway microbiologic cultures from dogs and cats with respiratory disease not requiring PPV were randomly sampled for comparison. Interventions – None. Measurements and Main Results – Patients with respiratory failure were more likely to have a gram‐negative enteric isolate identified (P<0.001), while patients with respiratory disease were more likely to have a gram‐negative nonenteric isolate (P<0.001) or anaerobic isolate (P<0.001) identified. Aerobic bacterial isolates from patients with respiratory failure were less likely to be susceptible to ampicillin (P=0.006), amoxicillin/clavulonate (P<0.001), chloramphenicol (P=0.004), enrofloxacin (P<0.001), ticarcillin/clavulonate (P=0.004), and the combination of ampicillin with enrofloxacin (P<0.001) than were aerobic bacterial isolates from patients with respiratory disease. Conclusions – Canine and feline patients with respiratory failure severe enough to require PPV exhibit a different pattern of bacterial isolates cultured from their airways when compared with isolates from patients with respiratory disease that has not resulted in ventilator dependence. These isolates are more likely to be resistant to commonly used antimicrobials/antimicrobial combinations than patients in the respiratory disease group. These findings suggest that in canine and feline patients with infectious lower respiratory tract disease, consideration of the severity of the pulmonary insult may allow for better prediction of likely isolates and their antimicrobial susceptibilities. Further prospective studies with a standardized collection technique are warranted.     

生物饲料添加剂中微生物污染情况调查分析

研究旨在了解生物饲料添加剂中微生物污染情况。随机抽取生产及使用环节的微生态制剂、酶制剂及标示有微生物成分或酶制剂成分的混合型饲料添加剂产品270批,依据现行标准规定的方法进行了沙门氏菌、志贺氏菌、金黄色葡萄球菌、大肠菌群、霉菌总数、蜡样芽孢杆菌等微生物指标的检测。结果表明,生物饲料添加剂中沙门氏菌的检出率为1.85%;大肠菌群的检出率为23.33%,超标率为21.11%,检出水平为<10～10~5CFU/g;霉菌的检出率为42.22%,超标率为8.89%,检出水平为<10～10~6CFU/g;蜡样芽孢杆菌检出率为39.56%,超标率为4.44%,检出水平为<10～10~7CFU/g。结果显示,生物饲料添加剂中存在一定程度的微生物污染情况,有必要对该类产品进行质量监控。     

Foraging and denning patterns of brushtail possums, and their possible relationship to contact with cattle and the transmission of bovine tuberculosis

Radio-tracking and direct observation were used over 18 months in 1990-92 to investigate both the use of sleeping dens and foraging activity by possums (Trichosurus vulpecula) on a 21 ha site in the Wairarapa used for a longitudinal study of bovine tuberculosis. Males had larger home ranges than females, and both sexes had larger activity areas during the autumn mating season than at other times of the year. Possums typically foraged in only a small area of their home ranges (termed an activity area) on any one night, and the areas used by individuals were commonly very similar over a series of nights. Activity areas overlapped extensively among possums. Possums used a limited number of dens, commonly in a small and in most cases a circumscribed part of their home range. No simultaneous den-sharing was found, with the exception of mother-joey pairs. The mortality of juveniles after independence was 36%. Only two of 25 juveniles under surveillance to detect dispersal dispersed more than 500 m off the study site, and both subsequently died. Grazing patterns of cattle meant that almost all accessible areas of the paddock were covered by at least some grazing cattle, and so all activity areas of possums within the paddock were covered by areas where cattle foraged. However, possums avoided contact with cattle, and when some cattle were excluded from access to the part of the paddock principally used by both tuberculous and healthy possums for denning, transmission of Mycobacterium bovis from possums to these cattle ceased, although there was subsequent transmission to deer. Cattle which grazed the area used principally for possum denning continued to become infected, and these denning areas appeared to be of importance in the transmission of tuberculosis.     

Changing patterns of West Nile virus transmission: altered vector competence and host susceptibility

West Nile virus (WNV) is a flavivirus (Flaviviridae) transmitted between Culex spp. mosquitoes and avian hosts. The virus has dramatically expanded its geographic range in the past ten years. Increases in global commerce, climate change, ecological factors and the emergence of novel viral genotypes likely play significant roles in the emergence of this virus; however, the exact mechanism and relative importance of each is uncertain. Previously WNV was primarily associated with febrile illness of children in endemic areas, but it was identified as a cause of neurological disease in humans in 1994. This modulation in disease presentation could be the result of the emergence of a more virulent genotype as well as the progression of the virus into areas in which the age structure of immunologically naïve individuals makes them more susceptible to severe neurological disease. Since its introduction to North America in 1999, a novel WNV genotype has been identified that has been demonstrated to disseminate more rapidly and with greater efficiency at elevated temperatures than the originally introduced strain, indicating the potential importance of temperature as a selective criteria for the emergence of WNV genotypes with increased vectorial capacity. Even prior to the North American introduction, a mutation associated with increased replication in avian hosts, identified to be under adaptive evolutionary pressure, has been identified, indicating that adaptation for increased replication within vertebrate hosts could play a role in increased transmission efficiency. Although stable in its evolutionary structure, WNV has demonstrated the capacity for rapidly adapting to both vertebrate hosts and invertebrate vectors and will likely continue to exploit novel ecological niches as it adapts to novel transmission foci.     

微生态制剂在畜禽饲料中的应用及相关的作用机制

随着动物营养研究和饲料生产的不断发展,微生态制剂的研究开发已经形成一股巨大的热潮。1988年我国学者在“益生素”、“促生素”、“益生菌”等概念基础上提出了“微生态制剂”的概念。它是一种给动物饲喂的活的微生物培养物,通过加强肠道微生物区系的屏障作用或通过增进非特异性免疫机能,增强抗病力和体质,防止病菌感染。同时,可以提高饲料利用率和生长率,与饲料各营养成分在畜禽体内消化吸收有密切关系。1965年,Lilly和Stillwell将益生素定义为“由一种微生物分泌刺激另一种     

微生物发酵床在动物生产中的应用研究

微生物发酵床不仅能够提高动物的生产性能和免疫功能,改善肉品质,提高养殖经济效益,而且能够减少养殖废弃物排放,改善养殖环境,是一种绿色、环保、节能、高效的养殖模式.但在使用微生物发酵床的过程中仍然存在一些问题,养殖户应合理选择微生物发酵床的垫料和发酵菌种,控制垫料的含水量和厚度,保证发酵的正常进行.为促进微生物发酵床的合...     

直接饲喂微生物在反刍动物生产上的应用

直接饲喂微生物（DFM）能提高育肥牛日增重和饲料利用率，提高奶牛泌乳量，改善幼龄反刍动物的健康状况和生产成绩。然而，DFM的作用很不稳定，其作用模式不明。文中主要介绍了DFM对反刍动物健康和生产性能的影响，讨论了其潜在的作用机理。并对有待于继续研究的问题进行了探讨。     

Design and analysis of an Actinobacillus pleuropneumoniae transmission experiment

This paper describes a methodology to quantify the transmission of Actinobacillus (A.) pleuropneumoniae from subclinically infected carrier pigs to susceptible contact pigs, and to test the effect of possible interventions on the transmission. The methodology includes the design of a transmission experiment, and a method with which A. pleuropneumoniae transmission can be quantified and with which the effect of an intervention on the transmission can be tested. The experimental design consists of two parts. First, subclinically infected carrier pigs are created by contact exposure of specific-pathogen-free pigs to endobronchially inoculated pigs. Second, transmission is observed from the group of carrier pigs to a second group of susceptible contact pigs after replacing the inoculated pigs by new contact pigs. The presented analytical method is a generalised linear model (GLM) with which the effect of an intervention on the susceptibility and infectivity can be tested separately, if the transmission is observed in heterogeneous populations. The concept of the experimental transmission model is illustrated by describing an A. pleuropneumoniae transmission experiment in which the effect of vaccination on the susceptibility is quantified. Although it could not be demonstrated that vaccination has an effect on the susceptibility of pigs, it was demonstrated that nasal excretion of A. pleuropneumoniae is related to the infectivity of pigs.     

Comparison of microbial isolates and susceptibility patterns from the external ear canal of dogs with otitis externa

Otic exudate was obtained from 33 dogs with otitis externa for cytopathology and culture. Two samples were taken from the same location in the external ear canal, for a total of 100 samples. Thirty-six (36%) samples isolated only a single organism, of which 21 (21%) were Malassezia spp. Two organisms were present in 23 (23%) of the samples. Cultures of the two samples agreed in 40 (80%) of the 50 pairs. Cytopathology agreed with culture results only 68% of the time. Cytopathology and culture may not be as definitive as previously assumed because of apparent variability of the microbial population within the external canal.     

中国明对虾(Fenneropenaeus chinensis)肠道微生物区系组成的分子分析

<正>中国明对虾主要分布在我国黄渤海和朝鲜西部沿海,南海部分海域也有少量存在,是我国重要的海水养殖对虾之一。中国明对虾是中国的特产,也是重要的出口水产品,无论是品质还是市场价格都远远高于其他养殖对虾品种,其最高养殖年产量曾达到近20万吨。而随其养殖规模的扩大,对虾疾病的发生越来越频繁,1993年爆发的病毒性流行病,使中国明对虾的养殖遭受毁灭性打击,此后始终未能全面恢复。     

瘤胃微生物多样性与分析技术的研究进展

瘤胃微生物区系是一个组成和功能极其复杂的体系,微生物的多样性决定着动物机体健康和生产性能。本文就瘤胃微生物多样性的研究进展和瘤胃微生物分类定量的技术手段以及益生菌对瘤胃微生物的作用作一综述。