Evaluation of the antigen relatedness and efficacy of a single vaccination with different infectious bronchitis virus strains against a challenge with Malaysian variant and QX-like IBV strains

BackgroundThe predominant infectious bronchitis virus (IBV) strains detected in chickens in Malaysia are the Malaysian variant (MV) and QX-like, which are associated with respiratory distress, nephropathy, and high mortality. On the other hand, the antigenic relatedness and efficacy of IBV vaccines against these 2 field IBV strains are not well characterized.ObjectivesThis study aimed to determine the antigen relatedness and efficacy of different IB vaccine strains against a challenge with MV and QX-like strains.MethodsThe antigen relatedness and the ability of different IB vaccine strains in conferring protection against MV and QX-like were assessed based on the clinical signs, macroscopic lesions, and ciliary activity.ResultsThe MV strain IBS037A/2014 showed minor antigenic subtype differences with the vaccine virus Mass H120 and 4/91 strains but showed major antigenic subtype differences with the K2 strain. The Malaysian QX-like strain IBS130/2015 showed major antigenic subtype differences with the MV strain IBS037A/2014 and the vaccine strains except for K2. Chickens vaccinated once with Mass (H120) or with non-Mass (4/91 and K2) developed antibody responses with the highest antibody titer detected in the groups vaccinated with H120 and 4/91. The mean ciliary activities of the vaccinated chickens were between 56 to 59% and 48 to 52% in chickens challenged with IBS037A/2014 and IBS130/2015, respectively. The vaccinated and challenged birds showed mild to severe lesions in the lungs and kidneys.ConclusionsDespite the minor antigenic subtype differences, a single inoculation with Mass or non-Mass vaccines could not protect against the MV IBS037A/2014 and QX-like IBS130/2015.     

优质抗病杂交粳稻滇杂31不同海拔适宜栽插密度初探

通过对优质抗病滇型杂交粳稻滇杂31不同栽插密度在云南温暖粳稻区的牟定县和温凉粳稻区的大理市进行试验,试验结果分析表明:滇杂31在温暖粳稻区的栽插密度以30.0万丛/hm2,2苗/丛产量最高,不同栽插密度之间产量差异达极显著水平;在温凉粳稻区的栽插密度以45.0万丛/hm2,2苗/丛产量最高,不同栽插密度之间产量差异达显著水平。     

多效唑对非洲菊试管苗生根的影响

不同质量浓度（０．１０～５０．００ｍｇ／Ｌ）的多效唑对非洲菊试管苗生根影响的研究结果表明，低浓度的多效唑（≤１０．００ｍｇ／Ｌ）能促进非洲菊试管苗生根，其中浓度以１ｍｇ／Ｌ的多效唑生根效果最佳；高浓度的多效唑（≥５０．００ｍｇ／Ｌ）则抑制非洲菊试管苗生根．     

鸡产蛋下降综合症(EDS—76)灭活油乳剂苗的研究 Ⅰ.灭活油乳剂苗的制备

在本试验中,司本-80和硬脂酸铝加入油相,吐温-80加入灭活的EDS-76尿囊毒为水相制备成油乳剂苗。福尔马林灭活病毒制备的疫苗其免疫效果高于热灭活病毒制备的疫苗,免疫后三周,前者的HI抗体水平达9.5log_2,而后者仅为4.0log_2.福尔马林灭活病毒制备的疫苗于腹腔、皮下注射小白鼠、豚鼠、兔子和10倍剂量接种产蛋鸡,结果均无不良反应;该疫苗为完全油包水剂型、不导电,滴于冷水表面不扩散,亲水亲油平衡值(HLB)为6.67;镜下所见疫苗颗粒为0.5μ直径大小。4℃存放6个月稳定,有效期至少6个月。     

用若干有害物饲喂仔鸡后的残留试验

在鸡饲料中添加若干个不同梯度剂量的有毒有害物汞、铅和镉。结果表明，饲料中各种有害物的添加量与鸡肉、鸡肝、鸡肾中的残留量呈正相关。在饲料中，中止添加有害物后，不同的有害物在机体中都有不同程度和速度的衰减。     

混凝土的各向同性损伤模型

本文以连续损伤力学理论为基础，根据Ｊ．Ｌａｍａｉｔｒｅ（１９７１）提出的“应变等铲性假说”，利用“利帕托夫强度理论”作为破坏准则，建立了各向同性损伤模型，并运用这一模型对混凝土材料的Ｐｆｅｉｆｆｅｒ和Ｂａｚａｎｔ试件在直剪和压剪载荷作用下的损伤发展过程进行了数值模拟，并与ＳＥＳＷＡＲＴＺ和ＮＭＴＡＨＡ实验结果作了比较，二者比较吻合，初步表明了本模型的有效性。     

论农地规模经营的一般规律及发展前景

分析研究了人口、生态和技术的变迁对农地规模经营的影响。在长期的历史变迁中，中国农业的发展在人口压力下形成了与追求产量最大化相一致的小规模经营，且随着集约化技术的发展，小规模经营愈加强化。技术变迁的历史表明：完善的市场化措施和社会化服务体系的建立，完全可以在目前小农经营基础上改造传统农业并促进农业生产的进一步发展。     

成都地区农田鼠类群落结构研究

本文对成都平原农田害鼠的种类、种群大小、群落结构及区系分布进行了研究,并用Kotila,P.M.的微机程序分析了群落的多样性、均匀度、相似系数和相异指数。     

上农香、黑糯等品种及其杂交后代选系的酯酶同工酶分析

本文利用同工酶电泳技术,分析了上农香、黑糯等4个品种及其6个杂交后代选系的酯酶同工酶谱。结果表明,不同品种（品系）酶谱基本相似;但也各有特异带,其中b_1、b_2带酶活性较强,可作为上农特种稻的特异性标志带。除Z_(17-3),其他杂交后代与母本相似度较高。