SNP及其在畜牧业中的应用前景

SNP(single nucleotide polymorphisns-单核苷酸多态性)是继限制性片段长度多态性和微卫星之后，新发展起来的第3代分子标记。已成为一类新的遗传标记，广泛应用于基因定位、克隆和遗传多样性研究。本文介绍了SNP的特性、检测方法及其在畜牧业研究生产中的广泛利用前景。并提出了SNP研究中遇到的一些问题。     

Cell cultures for diagnosis of arbovirus infections in livestock and wildlife

Summary Arboviruses can be isolated in serially propagated cells derived from various vertebrates and invertebrates. Cell cultures can be used for direct detection of antigen by fluorescent antibody and enzyme-linked immunosorbent assays, for nucleic acid hybridization, and for visualization of viruses with electron microscopy. Reagents for enzyme-linked immunosorbent assays for IgM and IgG antibodies, hemagglutination-inhibition, complement fixation, and serum dilution-plaque reduction neutralization tests can be prepared in cell cultures infected with these viruses. Thus, cell cultures can be used as laboratory hosts for essentially all isolation, identification, and serodiagnostic procedures for arboviruses. This paper outlines current methods for diagnosis of arbovirus infections in livestock and wildlife, describes certain of these techniques, and provides references for others.     

High Case-Fatality Rate for Human Anthrax,Northern Ghana, 2005–2016

The human cutaneous anthrax case-fatality rate is ≈1% when treated, 5%–20% when untreated. We report high case-fatality rates (median 35.0%; 95% CI 21.1%–66.7%) during 2005–2016 linked to livestock handling in northern Ghana, where veterinary resources are limited. Livestock vaccination and access to human treatment should be evaluated.     

哈巴河铁热克提林牧区蜱类调查研究

作者于1999年5月在新疆哈巴河铁热克提林牧区调查莱姆病时,采用布旗法和宿主检蜱法,对当地莱姆病媒介蜱类作了调查研究,捕获蜱类标本3090只,经整理鉴定,共系8种,其中森林革蜱D.silvarum1543,占捕获总数49.94％,银盾革蜱D.niveus1099只,占35.57％,草原草蜱D.nuttalli383只,占12.49％,边缘革蜱D.marginatus58只,占1.88％,嗜群血蜱H.concin-ma、铃头血蜱H.campanulata、全沟硬蜱I.persulcatus和残缘璃眼蜱Hy.detrtum共7只,占0.22％。当地蜱类在不同生境、不同寄主和不同时间内,其种类组成、活动及数量动态各不相同。     

Transmission of Brucellosis from Elk to Cattle and Bison,Greater Yellowstone Area,USA, 2002–2012

Bovine brucellosis has been nearly eliminated from livestock in the United States. Bison and elk in the Greater Yellowstone Area remain reservoirs for the disease. During 1990–2002, no known cases occurred in Greater Yellowstone Area livestock. Since then, 17 transmission events from wildlife to livestock have been investigated.     

Understanding Pig and Poultry Trade Networks and Farming Practices Within the Pacific Islands as a Basis for Surveillance

Pacific Island countries have large pig and poultry populations. Yet little is known about patterns of contact between animals and how this influences disease spread in these islands. The objectives of this study were to examine farmer practices and the movements of pig and poultry within the Pacific Islands using questionnaires and social network analysis (SNA) tools to understand disease spread in the region. Questionnaire‐based surveys were conducted in Fiji, Papua New Guinea (PNG), Solomon Islands and Vanuatu with interviews of 310 pig farmers and 491 poultry farmers. Pacific Island farmers were found to have few animals (median = 7 pigs/farm, IQR 4–12), (median = 50 chicken/farm, IQR 23–52), (median = 10 ducks/farm, IQR 4–25), (median = 12 Muscovy ducks/farm, IQR 7–28) and a diversified number of species. A large proportion of farmers (44.6–61.3%) do not implement any preventive or control measures, yet the majority (80.6–88%) did not experience any animal diseases over the past 12 months. Most farmers never ask for veterinary care, never engage in laboratory testing and do not report when their animals show clinical signs. Many pig farmers (31.8%) trade within their communities only and sell (24.5%) directly to consumers which reduces the risk of diseases spreading. Our results show an association between farmers that report having had disease on their farm in the past 12 months and movements of animals on and off their farms. The capitals of the studied provinces in PNG, Vanuatu and Solomon Islands were identified as the most connected nodes of both pig and poultry trade, while Fiji networks appeared much less connected. Our study found that farmer practices increased the risk of disease spread, but this was currently limited by trading practices. The SNA results serve as a basis for more targeted disease surveillance and better use of available resources for disease prevention and control.     

Swine-to-Human Transmission of Influenza A(H3N2) Virus at Agricultural Fairs,Ohio, USA, 2012

Agricultural fairs provide an opportunity for bidirectional transmission of influenza A viruses. We sought to determine influenza A virus activity among swine at fairs in the United States. As part of an ongoing active influenza A virus surveillance project, nasal swab samples were collected from exhibition swine at 40 selected Ohio agricultural fairs during 2012. Influenza A(H3N2) virus was isolated from swine at 10 of the fairs. According to a concurrent public health investigation, 7 of the 10 fairs were epidemiologically linked to confirmed human infections with influenza A(H3N2) variant virus. Comparison of genome sequences of the subtype H3N2 isolates recovered from humans and swine from each fair revealed nucleotide identities of >99.7%, confirming zoonotic transmission between swine and humans. All influenza A(H3N2) viruses isolated in this study, regardless of host species or fair, were >99.5% identical, indicating that 1 virus strain was widely circulating among exhibition swine in Ohio during 2012.     

现代畜牧产业经济联合体集聚效度分析

农牧民增收一直是"三农"问题的核心内容之一,如何提升农牧民收入也是党和国家非常关心的重点问题。本文基于新疆伊吾县"现代畜牧产业经济联合体(以下全文简称现代畜牧联合体)"的调查发现,该组织形式和经营模式在提升农牧民一次收入的同时,可以二次增加农牧民收入,有利于降低产品交易费用、产生规模效益、稳固范围经济效能、减少对农牧民生产积极性的挫伤,同时有利于形成品牌、便于产品质量安全追溯体系的构建,实现经济效益、社会效益和生态效益的综合协调发展。     

Serological relationship between a novel ovine pestivirus and classical swine fever virus

The genus Pestivirus comprises globally distributed members of the family Flaviviridae, which cause severe losses in livestock. The most common species of the genus are bovine viral diarrhoea virus type 1 (BVDV‐1) and type 2 (BVDV‐2), classical swine fever virus (CSFV) and border disease virus (BDV). Recently, a novel ovine pestivirus was repeatedly detected in aborted lamb foetuses on a farm located in the Brescia Province (Italy). Complete genome characterization of this isolate showed that it was highly divergent from known pestivirus species and that it was genetically closely related to CSFV. The aim of this study was to determine the serological relatedness between the identified novel pestivirus and BVDV, BDV and CSFV selected strains for which homologous serum was available, by antigenic characterization performed using cross‐neutralization assays. The serological relatedness was expressed as the coefficient of antigenic similarity (R). Both field and specific antisera raised against the ovine pestivirus neutralized the CSFV reference strain Diepholz with titres significantly higher than those specific for the BDV and BVDV strains. Furthermore, the calculated R values clearly indicated that the novel ovine pestivirus is antigenically more related to CSFV than to ruminant pestiviruses, in agreement with the results of the genomic analysis. This would have severe consequences on CSFV serology in the event of a switch to porcine hosts with implications for CSFV surveillance and porcine health management.     

Ergot Alkaloids Produced by Endophytic Fungi of the Genus Epichlo?

The development of fungal endophytes of the genus Epichloë in grasses results in the production of different groups of alkaloids, whose mechanism and biological spectrum of toxicity can differ considerably. Ergot alkaloids, when present in endophyte-infected tall fescue, are responsible for “fescue toxicosis” in livestock, whereas indole-diterpene alkaloids, when present in endophyte-infected ryegrass, are responsible for “ryegrass staggers”. In contrast, peramine and loline alkaloids are deterrent and/or toxic to insects. Other toxic effects in livestock associated with the consumption of endophyte-infected grass that contain ergot alkaloids include the “sleepy grass” and “drunken horse grass” diseases. Although ergovaline is the main ergopeptine alkaloid produced in endophyte-infected tall fescue and is recognized as responsible for fescue toxicosis, a number of questions still exist concerning the profile of alkaloid production in tall fescue and the worldwide distribution of tall fescue toxicosis. The purpose of this review is to present ergot alkaloids produced in endophyte-infected grass, the factors of variation of their level in plants, and the diseases observed in the mammalian species as relate to the profiles of alkaloid production. In the final section, interactions between ergot alkaloids and drug-metabolizing enzymes are presented as mechanisms that could contribute to toxicity.