一起鸭甲肝病毒1型和3型混合感染的研究报道

自山东省某疑似鸭肝炎发病鸭肝脏中分离到两株病毒,命名为TA1和TA2,分离毒分别回归3日龄雏鸭,可复制出鸭肝炎的典型症状和病理变化。利用鸭甲肝病毒1型（DHAV-1）和3型（DHAV-3）特异性引物进行RT-PCR 扩增,结果为阳性,经测序证实为DHAV-1和DHAV-3。分别扩增分离毒的VP1基因,经序列测定及遗传进化关系分析发现,分离毒TA1和DHAV-3毒株之间有较高的核苷酸序列相似性,与DHAV-3遗传距离最近,属于基因C型;分离毒TA2和DHAV-1毒株之间有较高的核苷酸序列相似性,与DHAV-1的遗传距离最近,属基因A型。     

几种不同类型饲料的加工方法

饲料加工是一个较为复杂的过程,尽管加工工艺通常都包括粉碎、混合、成型这些基本工序,但具体的工艺布置和加工参数都应根据饲料种类和所用的饲料原料作相应调整,因为不同的原料配方对成型饲料的生产性能有很大的影响。其中,原料特性包括物料的容重、粒度、含水量、粘结性、摩擦性和腐蚀性等。这些因素都影响着饲料产品质量和加工设备生产能力。因此,在饲料配方中,要适当考虑饲料原料特性,调整配方使之具有较好的制粒性能。而在加工工艺上,则要根据不同饲料原料和配方,选择合理的加工方法。本文根据饲料配方中淀粉、蛋白质、纤维、脂肪这几种成分在饲料中所占比例对饲料进行分类,探讨不同类型饲料的加工工艺及适宜的加工方法。     

Retrospective serological survey of antibodies to porcine circovirus type 1 and type 2.

A retrospective serological survey was performed to determine the presence of antibodies to porcine circovirus type 1 (PCV1) and porcine circovirus type 2 (PCV2) in serum samples collected from sows at slaughterhouses in Canada in 1985, 1989, and 1997. Each serum sample was tested by indirect immunofluorescence on PCV-free PK15 cells, on PCV1-infected PK15 cells and on PCV2-infected PK15 cells. For the 3 years studied, sera positive to PCV1 and PCV2 were identified and the number of sera positive for PCV2 was greater than the number of sera positive for PCV1. The results indicated 1) that PCV2 appears to be the main PCV type circulating in the Canadian pig population, 2) that PCV2 had been circulating in the Canadian pig population at least 10 years before the postweaning multisystemic wasting syndrome (PMWS) was reported, and 3) that serological evaluation using PCV1 underestimates the seroprevalence of PCV2.     

鉴别猪圆环病毒1型和2型的二重PCR方法的建立

根据GenBank上发表的PCV-1和PCV-2序列,设计2对引物分别扩增PCV-1和PCV-2的独特区域,长度为382 bp和222 bp.将PCR产物分别克隆至pMD-18T vector,经转化、PCR鉴定和序列测定,构建了PCV-1和PCV-2的阳性质粒,并等量混合作为二重PCR阳性模板.将2对PCR引物混合后,进行退火温度优化,敏感性和特异性试验,并用于临床检测.结果表明,该二重PCR方法可以特异性地鉴别PCV-1和PCV-2,最低检出量分别为0.1 ng和0.01 ng,敏感性较高.应用该方法可对临床样品进行准确、快速地诊断,为猪圆环病毒的临床诊断与流行病学调查等研究奠定了基础.     

Sequential histopathologic changes of type I, pre-type II and type II ostertagiasis in cattle

Yearling cattle in Louisiana were examined at monthly intervals for abomasal nematode burdens and histological lesions over a year. Tracer calves were grazed for 3 to 4 weeks and removed from pasture for 2 to 3 weeks, then slaughtered; a few animals were killed in extremis shortly after removal from pasture. Histological changes were correlated with worm burdens and characterized according to the type of Ostertagia ostertagi infection present. In cattle with acute Type I ostertagiasis, changes varied from eosinophil infiltration to glandular dilation and slight mucous cell hyperplasia with submucosal edema. During the summer months the cattle had worm burdens that were primarily early 4th stage larvae (EL4), with changes characterized by minimal glandular dilation and mucous cell metaplasia and moderate lymphoid cell proliferation and with intramucosal migration of EL4. In the autumn, the maturation of EL4 produced the Type II syndrome with severe glandular changes, prominent mucosal hyperplasia and marked lymphoid cell accumulation. With increased duration of the pre-Type II interval, there was greater development of the subepithelial lymphoid tissue and increased frequency of epithelial globule leukocytes. The lymphoproliferation which occurred during the prolonged pre-Type II interval appeared to be related to the increased severity and mortality seen with the Type II ostertagiasis syndrome.     

Epizootiological aspects of type 1 and type 4 equine herpesvirus infections among horse populations.

The dissemination of equine herpesvirus types 1 (EHV-1) and 4 (EHV-4) among various horse populations in Japan was investigated through the isolation and typing of virus strains from horses with respiratory diseases. Type specific monoclonal antibody pools were used for the typing of isolates. The 42 strains of EHV-1 and 64 strains of EHV-4 were isolated from 4593 nasal swabs and/or blood plasma samples collected from 3326 horses during a period from 1979 to 1990. All the strains of EHV-1 were isolated from racehorses only and during the winter season exclusively, when the epizootic of respiratory diseases occurred among racehorse populations at two Training Centers of the Japan Racing Association. In contrast, the strains of EHV-4 were isolated from horses irrespective of the season, facility, or horse population; foals and yearlings in breeding farms and our institute, rearing horses in rearing farms, and racehorses. Especially, 4 strains of EHV-4 were isolated from plasma samples containing buffy coat cells. We believe this is the first reported case of EHV-4 cell-associated viremia in the world. All 87 strains isolated from aborted fetuses were identified as EHV-1. The results suggest that EHV-1 is responsible for epizootic respiratory diseases in racehorses in the winter and abortion among mares at the late stage of gestation, and that EHV-4 causes respiratory diseases throughout the year among all horse populations.     

Comparison of type I and type II bovine viral diarrhea virus infection in swine.

Some isolates of type II bovine viral diarrhea virus (BVDV) are capable of causing severe clinical disease in cattle. Bovine viral diarrhea virus infection has been reported in pigs, but the ability of these more virulent isolates of type II BVDV to induce severe clinical disease in pigs is unknown. It was our objective to compare clinical, virologic, and pathologic findings between type I and type II BVDV infection in pigs. Noninfected control and BVDV-infected 2-month-old pigs were used. A noncytopathic type I and a noncytopathic type II BVDV isolate were chosen for evaluation in feeder age swine based upon preliminary in vitro and in vivo experiments. A dose titration study was performed using 4 groups of 4 pigs for each viral isolate. The groups were inoculated intranasally with either sham (control), 10(3), 10(5), or 10(7) TCID50 of virus. The pigs were examined daily and clinical findings were recorded. Antemortem and postmortem samples were collected for virus isolation. Neither the type I nor type II BVDV isolates resulted in clinical signs of disease in pigs. Bovine viral diarrhea virus was isolated from antemortem and postmortem samples from groups of pigs receiving the 10(5) and the 10(7) TCID50 dose of the type I BVDV isolate. In contrast, BVDV was only isolated from postmortem samples in the group of pigs receiving the 10(7) TCID50 dose of the type II BVDV isolate. Type I BVDV was able to establish infection in pigs at lower doses by intranasal instillation than type II BVDV. Infection of pigs with a type II isolate of BVDV known to cause severe disease in calves did not result in clinically apparent disease in pigs.     

猪圆环病毒2型及3型快速二重PCR检测方法的建立及其应用

针对猪圆环病毒2型(PCV2)和猪圆环病毒3型(PCV3)基因的保守序列设计了2对扩增PCV2和PCV3的特异性引物,通过优化各反应条件,建立同时检测PCV2和PCV3的二重PCR检测方法。敏感性和特异性结果显示,1.08×10~(-8)μg/μL是对PCV2和PCV3的最低检测限具有较好的灵敏度;而对猪细小病毒(PPV)、伪狂犬病病毒(PRV)、大肠杆菌、链球菌、副猪嗜血杆菌、胸膜肺炎放线杆菌的检测结果均无条带,表明所建立的方法具有较好的特异性。应用该方法检测了2017年9月—2018年8月从广西14个地市猪场采集的533份病猪死猪内脏组织,结果显示:PCV2阳性率为23.8%,PCV3阳性率为14.8%, PCV2和PCV3混合感染率为2.8%。广西14个地市中有12个地市的猪场送检样品检测出PCV2,有10个地市的猪场送检样品检测出PCV3,表明PCV2和PCV3在广西受检猪群中普遍存在,要重视和做好PCV2和PCV3感染的防控工作。     

禽副黏病毒2型研究进展

禽副粘病毒 2型 (PMV-2 )属于副粘病毒科、腮腺炎病毒属 ,是制备人用生物制品所用SPF鸡的必检项目。该病毒呈世界性分布 ,我国鸡群中的感染也普遍存在。 PMV-2单独感染SPF鸡仅引起轻微的呼吸道症状 ,但与 IBV、MG等禽呼吸道病病原混合感染会明显加强后者的致病作用。PMV-2的 HN基因的 ORF全长为 1 743 nt,编码一个由 580个氨基酸组成的蛋白 ,F基因较为保守 ,变异不是很大。文章重点介绍了近年来关于 PMV-2病原学、流行病学、致病性、分子生物学以及诊断和防治方法的最新研究进展。     

乳铁蛋白肽的研究现状及进展

<正>近年来抗菌肽由于自身的优点成为抗生素的替代品,已成为学术界研究与开发的热点,其中乳铁蛋白肽(Lactoferricin,Lfcin)因其强大的生物学功能而备受关注。最初是由Bellamy等从乳铁蛋白水解物中分离到一种乳铁蛋白多肽,即牛乳铁蛋白肽(LfcinB),此     

谷胱甘肽——一种新型饲用添加剂

谷胱甘肽广泛存在于动植物体内,是机体内重要的活性物质。本文综述了谷胱甘肽的理化特性、自然界中的分布、代谢过程、生物学功能及其制备方法。并简单展望了谷胱甘肽在动物生产中的应用前景。     

谷胱甘肽——种新型饲用添加剂

谷胱甘肽广泛存在于动植物体内．是机体内重要的活性物质。本综述了谷胱甘肽的理化特性、自然界中的分布、代谢过程、生物学功能及其制备疗法。并简单展望了谷胱甘肽在动物生产中的应用前景.     

新型功能性饲料添加剂——酪蛋白磷酸肽

由于分离技术和结构鉴定等研究方法的发展,研究者从牛奶蛋白质中分离提取出大量的小分子生物活性肽。研究表明这些生物活性肽有着重要的生理功能,具有潜在的开发应用前景,极受人们瞩目。酪蛋白磷酸肽(CaseinPhosphopeptides,简写为CPPs)就是其中的一种。它是一种由牛乳酪蛋白经蛋白酶酶解作用而得到的含有成簇磷酸丝氨酰基的多肽。在上世纪五六十年代CPPs被英国科学家发现,我国上世纪九十年代初开始研究。研究证明CPPs在促进钙、铁、锌离子的吸收和利用方面具有特效。另外,对动物免疫和繁殖等方面也有着重要的作用。本文将就CPPs的来…     

尕里巴牛染色体核型分析

利用细胞体外培养,对尕里巴牛的染色体进行了分析.结果表明,尕里巴牛的二倍体染色体数目为2n＝60.共有29对常染色体和1对性染色体.所有常染色体均为端部着丝点染色体;X与Y性染色体均为亚中着丝点染色体.研究发现,尕里巴牛染色体中还存在三倍体和四倍体.     

Niacin supplementation induces type II to type I muscle fiber transition in skeletal muscle of sheep

Background

It was recently shown that niacin supplementation counteracts the obesity-induced muscle fiber transition from oxidative type I to glycolytic type II and increases the number of type I fibers in skeletal muscle of obese Zucker rats. These effects were likely mediated by the induction of key regulators of fiber transition, PPARδ (encoded by PPARD), PGC-1α (encoded by PPARGC1A) and PGC-1β (encoded by PPARGC1B), leading to type II to type I fiber transition and upregulation of genes involved in oxidative metabolism. The aim of the present study was to investigate whether niacin administration also influences fiber distribution and the metabolic phenotype of different muscles [M. longissimus dorsi (LD), M. semimembranosus (SM), M. semitendinosus (ST)] in sheep as a model for ruminants. For this purpose, 16 male, 11 wk old Rhoen sheep were randomly allocated to two groups of 8 sheep each administered either no (control group) or 1 g niacin per day (niacin group) for 4 wk.

Results

After 4 wk, the percentage number of type I fibers in LD, SM and ST muscles was greater in the niacin group, whereas the percentage number of type II fibers was less in niacin group than in the control group (P < 0.05). The mRNA levels of PPARGC1A, PPARGC1B, and PPARD and the relative mRNA levels of genes involved in mitochondrial fatty acid uptake (CPT1B, SLC25A20), tricarboxylic acid cycle (SDHA), mitochondrial respiratory chain (COX5A, COX6A1), and angiogenesis (VEGFA) in LD, SM and ST muscles were greater (P < 0.05) or tended to be greater (P < 0.15) in the niacin group than in the control group.

Conclusions

The study shows that niacin supplementation induces muscle fiber transition from type II to type I, and thereby an oxidative metabolic phenotype of skeletal muscle in sheep as a model for ruminants. The enhanced capacity of skeletal muscle to utilize fatty acids in ruminants might be particularly useful during metabolic states in which fatty acids are excessively mobilized from adipose tissue, such as during the early lactating period in high producing cows.     

Molecular characterization and functional expression of equine interleukin-1 type I and type II receptor cDNAs

cDNA generated from lipopolysaccharide-stimulated equine peripheral blood mononuclear cells was used to amplify and clone type I and type II equine interleukin-1 receptors (IL-1RI and IL-1RII) using primers derived from semi-conserved regions between human and mouse IL-1RI and IL-1RII sequences, respectively. 5' and 3' terminal sequences of equine IL-1RI and IL-1RII were amplified by 5' and 3' rapid amplification of cDNA ends. The deduced amino acid sequence of equine IL-1RI demonstrated 77, 64 and 63% similarity with human, mouse and rat sequences, respectively. The predicted amino acid sequence of equine IL-1RII demonstrated 70, 60 and 58% similarity with human, mouse and rat sequences, respectively. Recombinant equine soluble IL-1RI and IL-1RII produced in insect cells bound recombinant equine IL-1alpha and IL-1beta. Furthermore, both receptors suppressed the growth inhibitory activities of equine IL-1alpha and IL-1beta toward A375 cells in a dose-dependent manner, indicating that the present equine IL-1RI and IL-1RII cDNA encodes biologically active proteins.