Involvement of spleen components of mature fowl in the primary and secondary humoral antibody response following experimental EDS'76 virus infection

Summary

Cellular changes in spleens of mature fowl in relation to both the primary and secondary humoral antibody response following experimentalEDS'76 virus infection were studied. The influence of splenectomy on humoral antibody response was also examined.

Experimental fowl had been naturally infected with fowl adenovirus (FAV) but did not possess precipitins to these viruses at the time of EDS’ 76 virus infection. Since EDS'76 infection provokes a recall of the group antibody to FAV, this infection simultaneously induces a primary response against EDS’ 76 virus and a secondary response due to the recall of the group antibody to FAV.

HI and precipitating antibodies toEDS'76 virus (primary response) werefirst detected at 6 and 8 days p.i. respectively. Curves of HI, precipating and neutralising antibody titres were biphasic; the first peak (IgM peak) occurred at 10–11 days p.i., the second (IgG peak) at 16–28 days p.i.

Precipitating antibodies to FAV (secondary response) were demonstrated from 4 days p.i. The curve of these antibody titres was also biphasic, with peaks at the same times as in the primary response.

Based on HI and AGP testing of primary and secondary immune response in both splenectomised and non‐splenectomised fowl it is concluded that in the primary response the spleen of the adult fowl is involved significantly in only IgM secretion, while in the secondary response it is likely that bothIgM and IgG are secreted in considerable amounts.

Clusters of lymphoblasts and plasmablasts were observed at 3 days p.i. in the red pulp. It is very likely that antigen‐antibody complexes are formed from that time and circulate bound to the surface of lymphocytes. These antigen‐loaded lymphocytes are ‘picked up’ from the blood stream by

– red pulp macrophages, leading to enhanced formation of lymphoblasts in the red pulp. Great numbers of these cells (which are very probably IgM secreting cells) were present on days 6 and 7 p.i., but were no longer detectable after day 10 p.i.

– macrophages of the macrophagalellipsoidal corona (MEC), leading to significant enlargement of the periellipsoidal lymphoid tissue(PELT) by an increase of the number of lymphocytes observedfrom days 4–12 p.i. The MEC was significantly enlarged from 7–12 days p.i., very likely due to an increased number of macrophages.

Following deposition of antigen in the white pulp, formation of follicles begins. The number of small, intact follicles includingfollicle precursors increasedfrom 6 days p.i. From 15 days p.i. to the end of the experiment both the number and size of follicles increased significantly.

Uptake and processing of antigen by macrophages is probably accompanied by death of some of these cells. This might explain the degenerative changes observed in large mesenchymal cells, probably macrophages, at 3 and 5 days p.i. in the red pulp and at 5 and 6 days especially in the MEC. Splenitis which was present at 3 and 5 days p.i. and oedema observed in and around ellipsoidal cells at 5 days p.i. may be due to mediators released from these degenerative macrophages.

A significantly increased number of follicles with lymphoblasts was seen from 2–15 days p.i. while lymphoblasts and plasmablasts were present in the PELT from 5–15 days p.i., but predominantly at 6 and 7 days p.i. It is likely that disruption of follicles and blast transformation of white pulp lymphoid cells are secondary response events. White pulp lymphoblastsand plasmablastsare probably IgG secreting cells.

Splenomegaly was observed at 3, 5 and 6 days after infection and was mainly due to swelling of red pulp macrophages and infiltration of granulocytes in the red pulp. Ellipsoidal and periellipsoidal changes could contribute to the splenomegaly at 5 and 6 days p.i.     

“粉末炭活性污泥法+Fenton试剂”强化处理抗生素生产废水的研究

采用"粉末炭活性污泥法+Fenton试剂"强化处理抗生素生产废水,与"普通活性污泥法"进行了对比试验。结果表明:"普通活性污泥法"处理抗生素生产废水后有机污染物COD平均浓度为759mg/L,平均去除率89.1%,达不到该药厂废水排放标准,而"粉末炭活性污泥法+Fenton试剂"强化处理抗生素生产废水后有机污染物COD平均浓度186mg/L,平均去除率为97.3%,完全达到该药厂排放标准。     

Descriptive epidemiological study of the use of antimicrobial drugs by companion animal veterinarians in New Zealand

Abstract

AIM: To describe the patterns of use of antimicrobial drugs by veterinary surgeons treating commonly presented bacterial infections in companion animals in New Zealand.

METHODS: A postal survey of 800 randomly selected companion animal veterinarians practicing in New Zealand was conducted between August and December 2008. Data were collected regarding the antimicrobials prescribed for recent cases of skin, ear and urinary tract infections; the use of culture and susceptibility testing; and veterinarian characteristics such as proportion of time spent treating companion animals and recent attendance at continuing professional development (CPD) events. Potential associations within the data were explored using extended mosaic plots and multivariable regression models.

RESULTS:Completed surveys from 393 respondents were available for analysis, providing data on systemic antimicrobial drug use for 1,799 cases of presumptive bacterial infections. The most frequently prescribed drugs were amoxicillin-clavulanic acid (864 cases, 48%), cephalexin (558, 31%), and fluoroquinolones (198, 11%). Of 359 cases of canine superficial pyoderma, 157 (44%) were treated with amoxicillin-clavulanic acid and 155 (43%) were treated with cephalexin with median reported treatment durations of 7 and 10 days, for these two drugs respectively. Culture and susceptibility tests had been used in 376 of 1,984 (19%) of all reported cases and 160 (43%) of these were suspected urinary tract infections. Practitioners that spent 100% of their time treating companion animals and who had attended a CPD course related to companion animals within the 12 months prior to completing the survey were more likely to submit a sample for culture and susceptibility testing and to prescribe longer courses of antimicrobials for the treatment of canine pyoderma than practitioners who spent less than 100% of their time treating companion animals and had not attended a CPD course in the last 12 months.

CONCLUSIONS: Broad-spectrum drugs considered by the World Health Organisation to be critically important for human health, such as fluoroquinolones and amoxicillin-clavulanic acid, are amongst the most frequently prescribed antimicrobials in companion animal medicine, and these drugs are often prescribed without submitting a sample for culture and susceptibility testing.

CLINICAL RELEVANCE: Many cases of superficial pyoderma were treated for less than the recommended duration of 21 days, which may contribute to a higher rate of recurrent pyoderma and the development of drug resistance within the causal bacteria. Veterinarians should be aware that the use of fluoroquinolones, in particular, should be based upon the results of a culture and susceptibility test.     

The effect of phenothiazine on cobalt-deficient and cobalt-dosed lambs

The mean serum folate concentrations of Large White sows were compared between one group of 13 animals, 43–80 days pregnant and another group of 9 animals at weaning when the litters were 28–30 days old. The mean concentration was higher in sows at weaning (p<0.05) and the lowest levels were found in sows no more than 51 days pregnant (p<0.05).     

Heritable characters of the red blood cells of sheep

Extract

From the start I want to make it clear that the research work described here is the work of one of us (J.V.E.), and the reason why I am presenting his work is that Evans comes from New Zealand and presented a paper on this subject to the annual meeting of the British Association for the Advancement of Science last September in Sheffield, so that it seemed appropriate that his work should also be presented to this Society.     

畜禽粪便厌氧发酵过程抗生素抗性基因归趋及驱动因子分析

针对畜禽养殖业抗生素抗性基因(antibiotic resistance genes, ARGs)污染问题,该文选取厌氧发酵技术,对比不同厌氧发酵体系内ARGs消长与潜在宿主菌,挖掘不同因子与ARGs的相互关系。结果表明,厌氧发酵体系内微生物群落变化是ARGs消长的主要驱动因子,确定ARGs的潜在宿主菌是目前研究的难点;抗生素和重金属也是ARGs消长的重要驱动因子,控制抗生素污染和重金属污染可有效减缓ARGs污染;可移动遗传元件在ARGs水平传播过程中起着重要作用。综合而言,厌氧发酵体系内各个因子直接或间接影响ARGs消长,其中工艺参数是控制整个厌氧发酵体系的先决因素,在特定工艺参数下,微生物群落与体系物化指标相互影响与制约;微生物通过分子内部可移动遗传元件实现ARGs在不同微生物之间的水平传播。综上所述,通过综合协调各类因子实现厌氧发酵体系内ARGs消控是今后研究重点。     

禁抗后仔猪细菌性腹泻的临床诊断与防治

为了促进食品安全和养猪业的健康发展，禁止在饲料中使用促生长抗生素势在必行。随着我国的饲料禁抗相关法规的推行，饲料企业被严格禁止在饲料生产过程中加入抗生素，这也导致了猪场疾病尤其是肠道疾病的高发，而仔猪肠道发育未完全，免疫系统未发育成熟，更容易发生严重的腹泻甚至死亡。文章对几种常见的仔猪细菌性腹泻疾病进行了回顾，病原包括大肠杆菌、沙门氏菌、魏氏梭菌，讨论了它们的临床症状与防控措施，为猪场在防控这些细菌性腹泻提供参考。     

牦牛瘤胃微生物抗生素抗性基因对3种外源性刺激因子的响应

通过给牦牛投喂硫酸头孢喹肟(CEF)、盐酸二氟沙星(DIF)和黄曲霉毒素B1(AFB1),并进行瘤胃微生物宏基因组测序,旨在揭示这3种外源性刺激因子对抗生素抗性基因(ARGs)种类、抗性类型、抗性机制等的影响,对于深入研究微生物抗性组特征和抗性机制具有重要价值。选取15头牦牛,随机分5组。Cef组和Dif组分别根据说明书推荐剂量按体重计算、灌服CEF 1 mg·kg^-1和DIF 1 mL·kg^-1;E1组和E2组分别按采食量投喂AFB120、60μg·kg^-1;C组为对照组。处理7 d后,采集瘤胃液,提取DNA,Illumina HiSeq测序,对reads counts进行标准化得到TPM值,并进行方差分析。结果显示,对照组共获得132种ARGs,分属30种抗性类型,其中,四环素类tetQ和tetW基因丰度较高;Cef组tetW基因丰度增加(P<0.05),Dif组tetQ丰度增加(P<0.05);Cef组四环素类和头孢菌素类抗性基因丰度增加(P<0.05),Dif组四环素类和氨基香豆素类抗性基因丰度增加(P<0.05),E1组氨基香豆素和青霉烯类抗性基因丰度增加(P<0.05),E2组青霉烯类、头孢菌素类等9类抗性基因丰度均增多(P<0.05);Dif组Erm基因23S核糖体RNA甲基转移酶丰度增加(P<0.05),E2组中ATP结合盒超家族等3种抗性机制相关基因的丰度增加(P<0.05);3种因子均显著增加四环素类ARGs宿主的种类。结论:瘤胃是蕴含丰富ARGs的储藏库,其中,四环素类抗生素抗性基因tetQ和tetW是主要的ARGs。不仅CEF和DIF使部分ARGs的种类、抗性类型以及耐药机制相关酶等的丰度升高,增加瘤胃微生物的耐药性,而且AFB1也具有类似作用,且高剂量AFB1对抗性类型的影响范围较抗生素大。这3种因子还导致携带四环素类ARGs宿主微生物的种类数量增加,从而强化横向转移机制,加快ARGs传播,增强微生物对四环素类的耐药性。     

食品中阪崎克罗诺杆菌的药物敏感性及分子分型研究

克罗诺杆菌是一种革兰氏阴性菌，是配方粉中威胁婴幼儿健康的主要致病菌。近年来，乳制品及食品中常有克罗诺杆菌耐药株的报道，耐药株的出现给临床治疗带来巨大挑战。为探究PFGE型别与耐药表型之间的关联性，采用BD PhoenixTM-100全自动细菌鉴定及药敏系统对食品分离的68株阪崎克罗诺杆菌进行药敏检测，共选择19种抗生素，并采用PFGE对其进行分子分型。结果表明：4株阪崎克罗诺杆菌具有耐药性，耐药率为5.88%。其中，3株对头孢唑啉耐药，1株对四环素耐药。18株菌表现为中介，其中16株对头孢唑啉中介，2株对氯霉素中介。所有菌株对其余16种抗生素均敏感。68株阪崎克罗诺杆菌可分成58个PFGE带型，其中PT037、PT050、PT054、PT007、PT043及PT046带型分别含有4、3、3、2、2、2株菌，其余52个带型各含1株菌，带型较分散。3株头孢唑啉耐药菌株包含3个PFGE带型，18株中介菌株包含16个PFGE带型。检测的阪崎克罗诺杆菌食品分离株耐药率较低，未发现多重耐药菌株，且呈现出高度基因多态性，菌株PFGE带型与耐药性之间无明显相关性。