Molecular detection of avian spirochete Borrelia anserina in Argas persicus ticks in Algeria

Argasid ticks are one of the most important poultry ectoparasites. They affect poultry directly through blood meal and indirectly through the transmission of pathogens essentially Borrelia anserina, agent of avian borreliosis, one of the most widespread poultry diseases in the world, and is of great economic importance. This study was conducted between April 2014 and March 2015 in the region of Ksar El Boukhari, Algeria, in order to investigate the presence of soft ticks in laying hen farms and to detect B. anserina bacteria using molecular tools. DNA was extracted and screened for the presence of Borrelia spp. DNA by real-time polymerase chain reaction (qPCR). Borrelia spp. screening was performed using primers and probe targeting the 16S rRNA gene. A total of 83 traditional laying hen farms were visited, of which 39 (46.98 %) were found infested with A. persicus tick. Molecular analysis revealed that 2/34 (5.88 %) of ticks were infected by B. anserina. None of the ticks tested were positive for Rickettsia spp., and Coxiella burnetii. These results constitute the first report in Algeria of A. persicus harboring B. anserina.     

利用“速服宁”进行种鸡场禽沙门氏杆菌病净化的初步研究

为对沙门氏菌及对产蛋率受精率控制,进行服用速服宁对鸡群的平板血检白痢阳性、产蛋率、死胚率检测试验,结果表明,使用速服宁可以控制减少鸡场禽沙门氏菌,鸡白痢阳性鸡转阴效果好,种鸡可再一次使用,鸡产蛋率和受精率也得到很大提高。     

生物安全隔离区划在禽流感防控中的应用

简要回顾了生物安全隔离区划的应用进展,重点介绍了生物安全隔离区划在禽流感防控中常用的技术手段,以期对我国禽流感防控工作和无禽流感生物安全隔离区建设提供参考。     

利用类病毒脂质体抗原检测H5N1亚型禽流感病毒抗体ELISA方法的建立

利用昆虫杆状病毒表达系统制备了H5N1亚型禽流感病毒(AIV)HA蛋白、类病毒脂质体和病毒样颗粒,分别作为包被抗原,建立了相应的检测H5N1亚型禽流感病毒抗体的ELISA方法。特异性试验、敏感性试验、重复性试验和稳定性试验结果表明,利用3种抗原包被所建立的ELISA方法均具有良好的重复性和稳定性,批间和批内变异系数均小于10%,但单独表达的HA蛋白和类病毒脂质体特异性更好,而且类病毒脂质体有更高的免疫反应性,与灭活全病毒相比安全性更高,故在H5N1亚型AIV抗体水平检测方面更具有应用前景。     

2株鸭源 H11N9亚型禽流感病毒的基因遗传进化及致病性分析

为了解从湖南省洞庭湖区鸭群中分离的2株 H11N9亚型禽流感病毒变异特点、进化规律及生物学特性,本研究对2株H11N9亚型禽流感病毒的HA、NA序列进行同源性和遗传进化分析,并用2株毒株对SPF鸡进行致病性试验。结果显示,本试验分离到2株 H11N9亚型禽流感毒株的 HA裂解位点均没有多个连续的碱性氨基酸插入,属于低致病性毒株;HA基因的受体结合位点均非常保守,具有典型的禽源性特征;NA基因序列与在周边国家野鸟中分离的H11N9亚型毒株的氨基酸同源性较高;鼻腔接种SPF鸡后,均能使鸡感染并通过喉头或泄殖腔排毒,但感染的鸡均不表现明显的临床症状,并且不能使同居鸡感染排毒。     

Hemagglutinin glycosylation modulates the pathogenicity and antigenicity of the H5N1 avian influenza virus

The location and number of glycosylation in HA proteins exhibit large variations among H5 subtype avian influenza viruses (AIVs). To investigate the effect of glycosylation in the globular head of HA on the pathogenicity and antigenicity of H5N1 AIVs, seven rescued AIVs differing in their glycosylation patterns (144N, 158N and 169N) within the HA globular head of A/Mallard/Huadong/S/2005 were generated using site directed mutagenesis. Results showed that loss of glycosylation 158N was the prerequisite for H5 AIV binding to the α2,6-linked receptor. Only in conjunction with the removal of the 158N glycosylation, the H5 AIVs harboring both 144N and 169N glycosylations obtained an optimal binding preference to the α2,6-linked receptor. Compared with the wild-type virus, growth of viruses lacking glycosylation at either 158N or 169N was significantly reduced both in MDCK and A549 cells, while replication of viruses with additional glycosylation 144N was significantly promoted. Mutant viruses with loss of 158N or 169N glycosylation sites showed increased pathogenicity, systemic spread and pulmonary inflammation in mice compared to the wild-type H5N1 virus. In addition, chicken studies demonstrated that inactivated de-glycosylation 169N mutant induced cross-reaction HI and neutralization antibody against various clades of H5N1 AIVs. Moreover, this type of glycan pattern vaccine virus provided better cross-protection in chickens compared to wild-type vaccine virus. Thus, the glycosylation alteration of HA should be considered in the global surveillance and vaccine design of H5 subtype AIVs.