Control of highly pathogenic avian influenza through vaccination

The stamping-out strategy has been used to control highly pathogenic avian influenza viruses in many countries,driven by the belief that vaccination would not be successful against such viruses and fears that avian influenza virus in vaccinated birds would evolve more rapidly and pose a greater risk to humans.In this review,we summarize the successes in controlling highly pathogenic avian influenza in China and make suggestions regarding the requirements for vaccine selection and effectiveness.In addition,we present evidence that vaccination of poultry not only eliminates human infection with avian influenza virus,but also significantly reduces and abolishes some harmful characteristics of avian influenza virus.

A novel live attenuated vaccine candidate protects chickens against subtype B avian metapneumovirus

Avian metapneumovirus(aMPV) is a highly contagious pathogen that causes acute upper respiratory tract diseases in chickens and turkeys, resulting in serious economic losses. Subtype B aMPV has recently become the dominant epidemic strain in China. We developed an attenuated aMPV subtype B strain by serial passaging in Vero cells and evaluated its safety and efficacy as a vaccine candidate. The safety test showed that after the 30th passage, the LN16-A strain was fully attenuated, as clinical signs of infection and histological lesions were absent after inoculation.The LN16-A strain did not revert to a virulent strain after five serial passages in chickens. The genomic sequence of LN16-A differed from that of the parent wild-type LN16(wtLN16) strain and had nine amino acid mutations. In chickens, a single immunization with LN16-A induced robust humoral and cellular immune responses, including the abundant production of neutralizing antibodies, CD4^(+) T lymphocytes, and the Th1(IFN-γ) and Th2(IL-4 and IL-6)cytokines. We also confirmed that LN16-A provided 100% protection against subtype B aMPV and significantly reduced viral shedding and turbinate inflammation. Our findings suggest that the LN16-A strain is a promising live attenuated vaccine candidate that can prevent infection with subtype B aMPV.

Genetic and biological properties of H9N2 avian influenza viruses isolated in central China from2020 to 2022

The H9N2 subtype of avian influenza virus(AIV)is widely prevalent in poultry and wild birds globally,and has become the predominant subtype circulating in poultry in China.The H9N2 AIV can directly or indirectly(by serving as a"donor virus")infect humans,posing a significant threat to public health.Currently,there is a lack of in-depth research on the prevalence of H9N2 viruses in Shanxi Province,central China.In this study,we isolated 14 H9N2 AIVs from October 2020 to April 2022 in Shanxi Province,and genetic analysis revealed that these viruses belonged to 7 different genotypes.Our study on animals revealed that the H9N2 strains we identified displayed high transmission efficiency among chicken populations,and exhibited diverse replication abilities within these birds.These viruses could replicate efficiently in the lungs of mice,with one strain also demonstrating the capacity to reproduce in organs like the brain and kidneys.At the cellular level,the replication ability of different H9N2 strains was evaluated using plaque formation assays and multi-step growth curve assays,revealing significant differences in the replication and proliferation efficiency of the various H9N2 viruses at the cellular level.The antigenicity analysis suggested that these isolates could be classified into 2 separate antigenic clusters.Our research provides crucial data to help understand the prevalence and biological characteristics of H9N2 AIVs in central China.It also highlights the necessity of enhancing the surveillance of H9N2 AIVs.

Antibodies elicited by Newcastle disease virus-vectored H7N9 avian influenza vaccine are functional in activating the complement system

H7N9 subtype avian influenza virus poses a great challenge for poultry industry.Newcastle disease virus(NDV)-vectored H7N9 avian influenza vaccines(NDV_(vec)H7N9)are effective in disease control because they are protective and allow mass administration.Of note,these vaccines elicit undetectable H7N9-specific hemagglutination-inhibition(HI)but high IgG antibodies in chickens.However,the molecular basis and protective mechanism underlying this particular antibody immunity remain unclear.Herein,immunization with an NDV_(vec)H7N9 induced low anti-H7N9 HI and virus neutralization titers but high levels of hemagglutinin(HA)-binding IgG antibodies in chickens.Three residues(S150,G151 and S152)in HA of H7N9 virus were identified as the dominant epitopes recognized by the NDV_(vec)H7N9 immune serum.Passively transferred NDV_(vec)H7N9 immune serum conferred complete protection against H7N9 virus infection in chickens.The NDV_(vec)H7N9 immune serum can mediate a potent lysis of HA-expressing and H7N9 virus-infected cells and significantly suppress H7N9 virus infectivity.These activities of the serum were significantly impaired after heat-inactivation or treatment with complement inhibitor,suggesting the engagement of the complement system.Moreover,mutations in the 150-SGS-152 sites in HA resulted in significant reductions in cell lysis and virus neutralization mediated by the NDV_(vec)H7N9 immune serum,indicating the requirement of antibody-antigen binding for complement activity.Therefore,antibodies induced by the NDV_(vec)H7N9 can activate antibody-dependent complement-mediated lysis of H7N9 virus-infected cells and complement-mediated neutralization of H7N9 virus.Our findings unveiled a novel role of the complement in protection conferred by the NDV_(vec)H7N9,highlighting a potential benefit of engaging the complement system in H7N9 vaccine design.

The virulence regulator AbsR in avian pathogenic Escherichia coli has pleiotropic effects on bacterial physiology

Avian pathogenic Escherichia coli(APEC)belonging to extraintestinal pathogenic E.coli(ExPEC)can cause severe infections in extraintestinal tissues in birds and humans,such as the lungs and blood.MprA(microcin production regulation,locus A,herein renamed AbsR,a blood survival regulator),a member of the MarR(multiple antibiotic resistance regulator)transcriptional regulator family,governs the expression of capsule biosynthetic genes in human ExPEC and represents a promising druggable target for antimicrobials.However,a deep understanding of the AbsR regulatory mechanism as well as its regulon is lacking.In this study,we present a systems-level analysis of the APEC AbsR regulon using ChIP-Seq(chromatin immunoprecipitation sequencing)and RNA-Seq(RNA sequencing)methods.We found that AbsR directly regulates 99 genes and indirectly regulates 667 genes.Furthermore,we showed that:1)AbsR contributes to antiphagocytotic effects by macrophages and virulence in a mouse model for systemic infection by directly activating the capsular gene cluster;2)AbsR positively impacts biofilm formation via direct regulation of the T2SS(type II secretion system)but plays a marginal role in virulence;and 3)AbsR directly upregulates the acid tolerance signaling system EvgAS to withstand acid stress but is dispensable in ExPEC virulence.Finally,our data indicate that the role of AbsR in virulence gene regulation is relatively conserved in ExPEC strains.Altogether,this study provides a comprehensive analysis of the AbsR regulon and regulatory mechanism,and our data suggest that AbsR likely influences virulence primarily through the control of capsule production.Interestingly,we found that AbsR severely represses the expression of the type I-F CRISPR(clustered regularly interspaced short palindromic repeats)-Cas(CRISPR associated)systems,which could have implications in CRISPR biology and application.

A Speculation: Avian Migration and the K-T Extinction

One caveat to the dinosaur’s extinction is the conclusion that avian dinosaurs survived and became ancestors of birds. Their mobility enabled them to migrate great distances and find the nutrients needed to survive. Given this scenario, could the current observable migration of birds (the “dinosaurian offspring”) now be related? Migration is the regular seasonal movement undertaken by many species of birds, with the most common pattern, flying north in the Northern spring to breed in the temperate or Arctic summer and returning in the Northern autumn to wintering grounds in warmer regions of the south. The primary motivation for migration appears to be food. None of the major North-South migratory pathways fly over the Caribbean but three main fly ways, past to the west of the theorized K-T impact centre. Due to their ability to fly, the “avian Dinosaurs” adapted and survived very quickly in response to the disaster that marked the K-T boundary. It is an interesting speculation that the avian migration that we witness today is rooted in an event that occurred 66 million years ago! But it does explain why the migratory birds mostly fly from Polar summer to polar summer when they could just be as easily fly from Polar zone to the warmer equatorial region and back. In the recent article in Nature by Melanie During about identifying the late spring timing of the “Astro disaster”, it can be cited as consistent with my speculation. A late April early May Impact as suggested by During would have seen these migrations completely. The western migratory routes would have been found to be “luxurious” in vegetation in that first northern autumn after the “Astro-impact” while all eastern routes would have still been barren.

More than a simple egg:Underlying mechanisms of cold tolerance in avian embryos

Avian embryos,which develop within eggs,exhibit remarkable tolerance to extremely low temperatures.Despite being a common trait among all birds,the mechanisms underlying this cold tolerance in avian embryos remain largely unknown.To gain a better understanding of this phenomenon and the coping mechanisms involved,we reviewed the literature on severe cold tolerance in embryos of both wild and domestic birds.We found that embryos of different bird orders exhibit tolerance to severe cold during their development.In response to cold stress,embryos slow down their heartbeat rates and metabolism.In severe cold temperatures,embryos can suspend these processes,entering a torpid-like state of cardiac arrest.To compensate for these developmental delays,embryos extend their regular incubation periods.Depending on their embryonic age,embryos of all bird species can tolerate acute severe cold regimes;only a few tolerate chronic severe cold regimes.We also discussed various extrinsic and intrinsic factors that affect the tolerance of bird embryos to low temperatures before and after incubation.Cold tolerance appears to be a heritable trait shared by wild and domestic embryos of all bird classes,regardless of egg size or development(altricial/precocial).Driven by environmental variability,cold tolerance in avian embryos is an optimal physiological and ecological strategy to mitigate the adverse effects of cold conditions on their development in response to fluctuating environmental temperatures.

A novel candidate gene CLN8 regulates fat deposition in avian

Background The fat deposition has a crucial role in animal meat flavor,and fat deposition-related traits are vital for breeding in the commercial duck industry.Avian fat-related traits are typical complex phenotypes,which need a large amount of data to analyze the genetic loci.Results In this study,we performed a new phenotypic analysis of fat traits and genotyped whole-genome varia-tions for 1,246 ducks,and combed with previous GWAS data to reach 1,880 ducks for following analysis.The carcass composition traits,subcutaneous fat weight(SFW),subcutaneous fat percentage(SFP),abdominal fat weight(AFW),abdominal fat percentage(AFP)and the body weight of day 42(BW42)for each duck were collected.We identified a set of new loci that affect the traits related to fat deposition in avian.Among these loci,ceroid-lipofuscinosis,neuronal 8(CLN8)is a novel candidate gene controlling fat deposition.We investigated its novel function and regulation in avian adipogenesis.Five significant SNPs(the most significant SNP,P-value=21.37E-12)and a single haplotype were detected in the upstream of CLN8 for subcutaneous fat percentage.Subsequently,luciferase assay demonstrated that 5 linked SNPs in the upstream of the CLN8 gene significantly decreased the transcriptional activity of CLN8.Further,ATAC-seq analysis showed that transcription factor binding sites were identified in a region close to the haplotype.A set of luciferase reporter gene vectors that contained different deletion fragments of the CLN8 promoter were con-structed,and the core promoter area of CLN8 was finally identified in the-1,884/-1,207 bp region of the 5′flanking sequences,which contains adipogenesis-related transcription factors binding sites.Moreover,the over-expression of CLN8 can remarkably facilitate adipocyte differentiation in ICPs.Consistent with these,the global transcriptome profiling and functional analysis of the over-expressed CLN8 in the cell line further revealed that the lipid biosynthetic process during the adipogenesis was significantly enriched.Conclusions Our results demonstrated that CLN8 is a positive regulator of avian adipocyte differentiation.These findings identify a novel function of CLN8 in adipocyte differentiation,which provides important clues for the further study of the mechanism of avian fat deposition.

H7N9 avian influenza with first manifestation of occipital neuralgia:A case report

BACKGROUND Most of the first symptoms of avian influenza are respiratory symptoms,and cases with occipital neuralgia as the first manifestation are rarely reported.CASE SUMMARY A middle-aged patient complaining of paroxysmal pain behind the ear was admitted to our hospital.The patient’s condition changed rapidly,and high fever,unexpected respiratory failure,and multiple organ failure developed rapidly.The patient was diagnosed with H7N9 avian influenza based on etiology.CONCLUSION We believe that the etiology of occipital neuralgia is complex and could be the earliest manifestation of severe diseases.The possibility of an infectious disease should be considered when occipital neuralgia is accompanied by fever.Avian influenza is one of these causative agents.

Activin Gene in Avian Species: A Case Study

Among the avian species, understanding the roles of activin happen to be a dominant challenge in genetic evolution due to its complexity in nature. A case study of the activin gene in avian species was carried out using bioinformatics. As a sedentary bird, guinea fowl is more susceptible to local selection processes and needs a proper genetic study for conservation. The present study provides the basis for the use of activin or its target genes for the improvement of impaired wound healing, and activin antagonists for the prevention and treatment of fibrosis and the end of malignant tumors that over-express activin. The information provided will serve as a basic tool for broader genetic diversity studies to identify valuable poultry genetic resources and major genes for the development of breeding programs. This study was done by retrieving hundred (100) nucleotides and amino acid sequences of the activin gene belonging to guinea fowl and other avians from the GeneBank, aligning the sequences using BlastP determined the percent identity and phylogenetic relationship of the activin gene of guinea fowl and other avians. The shortest activin nucleotide sequence (467 bp) was observed in chicken and the longest (39896445 bp) in duck. Using the comparative sequence analysis, it was observed that the activin gene of chickens, turkeys and guinea fowl shared percent identity ranging from 91% to 95%. The percent identity reflects the degree of relatedness of species. Although closely related (90%) in ancestral line, the activin gene of guinea fowl and quail cannot be compared with guinea fowl-turkey (95%) nor guinea fowl-chicken (90%), in both biological functions and evolutionary relationship. Finally, the percent identity and similarity in function of the activin gene of guinea fowl, turkey, and chicken were in the range of 93% - 100%, indicating that the activin gene of avians possesses similar functions, well conserved and is very effective in performing functions like increasing FSH bindings, FSH-induced aromatization, improves wound healing and enhances scar formation, regulates morphogenesis of branching organs, and enhances ovarian folliculogenesis. The study, therefore, recommends farmers select and breed for activin genes in order to promote reproductive efficiency, thereby barricading species extinction.

Avian malaria,haematocrit,and body condition in invasive wetland passerines settled in southwestern Spain

Avian malaria and related haemosporidian parasites can negatively impact fitness in many songbirds.Research on the malaria infection and its physiological costs on their avian hosts is heavily skewed toward native passerines,with exotic species underrepresented.However,introduced species may carry on and spread new pathogens to native species,and play a role on parasite transmission cycle in invaded bird communities as pathogen reservoir.Here,we molecularly assess the prevalence and diversity of haemosporidian parasites in three introduced wetland passerines(the Red Avadavat Amandava amandava,the Yellow-crowned Bishop Euplectes afer,and the Common Waxbill Estrilda astrild)captured during the same season in southwestern Spain.We also explored the relation between parasite infection,body condition,haematocrit,and uropygial gland volume.We detected an overall parasite prevalence of 3.55%,where Common Waxbills showed higher prevalence(6.94%)than Red Avadavats(1.51%).None Yellow-crowned Bishops were infected with haemosporidians.Almost 60%of infections were caused by Leucocytozoon,and about 40%by Plasmodium.We identified four unique lineages of Plasmodium and three of Leucocytozoon.Moreover,91%of the identified host-parasite interactions represented new host records for these haemosporidian parasites.Parasite infection was not related to body condition,haematocrit,and uropygial gland volume of the wetland passerines.Haematocrit values varied seasonally among bird species.Additionally,haematocrit was positively related to body condition in the Yellow-crowned Bishops,but not in the other species.Red Avadavats had higher haematocrit levels than Yellow-crowned Bishops,whereas Common Waxbills showed the lower haematocrit values.The uropygial gland volume was positively correlated with body condition in all bird species.Common Waxbills showed higher uropygial gland volumes related to their body size than birds from other two species.These outcomes highlight the importance of exotic invasive species in the transmission dynamics of haemosporidian parasites.

The value of community science data to analyze long-term avian trends in understudied regions:The state of birds in Türkiye

Recent studies have revealed concerning declines in bird populations in Europe and other parts of the world.In understudied but biodiverse regions,especially those that are located along key migratory flyways,there is an unmet need to evaluate the status of resident and migratory birdlife for avian conservation ecology.This is especially urgent at a time when recent regional studies have highlighted the scale of the decline of the European and Palearctic avifauna.Rapidly growing community science datasets may help bridge the gaps in our understanding of long-term regional avifaunal trends.In this study,we used eBird data submitted by observers in Türkiye to undertake the first long-term assessment of the state of the country’s birds from 2001 to 2022.We evaluated population trends based on presence-absence data of species to determine if any birds have significantly increased or decreased in the country so far this century.We provide a list of trends for 418 bird species that had large enough sample sizes of eBird observations from Türkiye,and highlight which species have significantly declined or increased.We found that 63 species have significantly declined in detection while 120 have significantly increased during the study period.Our findings provide a baseline for the future monitoring of Türkiye’s birds and help contextualize population changes of birds in Türkiye against those occurring at the continental(Palearctic)scale.Additionally,we include movement classifications for all of the bird species in this study.We also provide a framework to effectively use eBird data to assess long-term avifaunal changes at the country-level in other understudied regions.Finally,we highlight ways in which eBirders in Türkiye and elsewhere can strengthen the quality and value of community ornithology data for population assessments and avian conservation ecology.

Changes in Avian Spring Arrival Dates of 115 Species in the Central Appalachians over 127 Years

Global climate change affects many facets of avian ecology, such as shifts in breeding phenology and migration patterns. Migrating bird species respond to changes in climate by shifting their temporal patterns of spring migration. However, variation in species’ responses exists based on various life history traits, which exposes some species to an increased risk of phenological mismatch. This study examined the spring arrival dates of 115 migrating species over 127 years (1889-2015) using archival sources in West Virginia, USA, making this research unique in the length of study, the high number of species studied, and the historical crowd-sourced observations analyzed. Of the 115 taxa, 45 showed significant negative slopes of spring arrival dates (arriving earlier in the spring) plotted against the year. In contrast, only nine species showed positive slopes (arriving later in the spring), albeit non-significant. The average advance of spring arrival date for all species was 1.7 days per decade, and an advance of 2.6 days per decade in species that showed significance. Arrival dates were associated with increasing spring temperatures—for each 1˚C increase, the arrival date advanced by 0.81 days/decade. Several life history traits were linked to species that advanced their first arrival dates, including a shorter distance migrated to reach wintering grounds, increasing populations, and foraging habitat. Most avian species are advancing their spring arrival dates in response to climate change. However, the implications of earlier spring arrival are unclear. We draw attention to shifts in arrival dates and wintering ranges, leading to a possible increase in overwintering in the mid-latitudes of North America.

禽白血病病毒p27抗原ELISA检测试剂盒的比较与评估

为了更好地进行禽白血病监测与净化,研究使用由蛋清、细胞培养物、胎粪等多种样品组成的样品盘对7种禽白血病病毒(Avian leukosis virus,ALV)p27抗原ELISA检测试剂盒(国产试剂盒DA、DB、DC,进口试剂盒IA、IB、IC、IDEXX)进行比较。结果显示:从分析特性上看,试剂盒分析特异性均较好,未观察到与其他常见禽源病毒的交叉反应;与IDEXX相比,DA、IA的分析敏感性较高,DB、IC其次,DC、IB较低,对于ALV不同亚群,各种试剂盒分析敏感性差异可达2~3个稀释度;从诊断特性上看,与IDEXX相比,DB、DC和IC的诊断敏感性和诊断特异性均高于90%;DA、IA和IB与IDEXX的诊断敏感性和诊断特异性均高于80%;各试剂盒对于不同类型样品(DF-1细胞培养物、蛋清、胎粪)的诊断敏感性和诊断特异性存在差异;从重复性上看,DA和IA的批内变异系数均在15%以内。综上所述,与IDEXX相比,当前国产p27抗原ELISA检测试剂盒DA和DB、进口p27抗原ELISA检测试剂盒IA和IC的各项性能可满足禽白血病净化各阶段对不同类型样品的检测需求。

Diagnosis and Prevention of Avian Leukosis

This paper introduced the characteristics of avian leukosis from the aspects of pathogen,epidemiology,clinical symptoms,and anatomical symptoms,and puts forward clinical comprehensive diagnosis and laboratory diagnostic methods.Besides,the disease is also differentiated from similar diseases of chicken such as Marek's disease,infectious bursal disease and reticuloendothelial hyperplasia.Finally,the prevention and control measures against the disease were proposed.

茶黄素体外抑菌作用研究

通过体外试验研究茶黄素对大肠埃希氏菌、金黄色葡萄球菌、枯草芽孢杆菌、肠球菌、禽肺炎克雷伯、鸭源鸡杆菌、禽肠炎沙门氏菌、野鸟黏质沙雷氏菌、禽巴氏杆菌的抑菌作用。采用最低抑菌浓度(MIC)和最小杀菌浓度(MBC)测定法研究茶黄素的抑菌作用及杀菌作用。结果显示,茶黄素对禽巴氏杆菌、鸭源鸡杆菌等具有抑菌作用,并与其浓度呈正相关,而对大肠埃希氏菌、禽肠炎沙门氏菌、黏质沙雷氏菌等无作用;茶黄素浓度为128μg/mL时,其对鸭源鸡杆菌生长具有抑制作用,当茶黄素浓度为512μg/mL时,其对禽巴氏杆菌C48-1生长具有抑制作用;当茶黄素浓度为512μg/mL时,其对禽巴氏杆菌和鸭源鸡杆菌具有杀菌作用。茶黄素在MBC浓度时能抑制生物被膜的形成能力。结果表明,茶黄素是一种天然抗菌剂,具有优良的替抗前景,促进绿色健康养殖。

2014-2018年新疆人感染H7N9禽流感分子流行病学特征分析

目的分析2014-2018年新疆14例人感染H7N9禽流感病例的分子流行病学特征,为防控及治疗提供科学依据。方法提取核酸后采用高通量基因测序技术获得基因组序列,并用生物信息学分析软件对基因组序列进行同源性分析、进化分析、变异位点分析及同源建模。结果14例人感染H7N9禽流感病毒HA基因核苷酸同源性介于97.39%~100%,氨基酸同源性介于98.38%~100%;NA基因核苷酸同源性介于97.73%~100%,氨基酸同源性介于97.73%~100%,均属于长江三角洲谱系和低致病性禽流感病毒,分属于2个亚分支,与A/Hunan/02650/2016疫苗株最为接近。HA蛋白G186V、T160A全部发生了变异,Q226L中13株病毒发生了变异,NA蛋白4个关键的神经氨酸酶抑制剂耐药位点全部未发生变异。M2蛋白S31N和V27A位点全部发生了突变,PB1蛋白T368V位点全部发生了突变,PA蛋白位点K356R全部发生了突变。结论新疆H7N9禽流感病毒具有双受体结合性,对金刚烷胺类药物耐药,对神经氨酸酶抑制剂敏感,可在疾病发生早期及时使用神经氨酸酶抑制剂。需加强禽流感病毒基因组变化的监测,做好基因突变的应对措施。

2020-2023年山东省涉禽外环境禽流感病毒监测分析

目的了解山东省涉禽场所外环境中禽流感病毒的污染情况,为人感染禽流感疫情的防控提供科学依据。方法2020-2023年从山东省16个地市4类涉禽场所采集外环境样本,使用实时荧光定量PCR法进行A型流感病毒核酸检测,阳性样本再进行H5、H7和H9亚型禽流感病毒的核酸分型,描述山东省涉禽外环境中禽流感病毒的流行病学特征,率间比较采用χ^(2)检验进行结果分析。结果2020-2023年,山东省涉禽场所共采集外环境标本6523份,检出禽流感病毒阳性1007份,阳性率为15.44%。H5、H7和H9亚型及混合感染均有检出,阳性标本中以H9亚型为主(88.48%)。不同地市阳性率差异较大(χ^(2)=431.956,P<0.001),其中阳性率最高的地市达28.93%。不同监测场所(χ^(2)=304.604,P<0.001)、不同类型样本(χ^(2)=109.678,P<0.001)、不同季度(χ^(2)=64.963,P<0.001)阳性率差异有统计学意义。其中,监测场所以城乡活禽市场阳性检出率(20.12%)最高,样本类型中宰杀或摆放禽肉案板表面擦拭标本阳性检出率(22.56%)高于其他样本,阳性检出率最高峰出现在春季(20.31%)。结论山东省涉禽外环境中普遍存在禽流感病毒污染,H9亚型为主要病原体,H5、H7亚型共流行,存在人感染禽流感的风险,应加强重点季节、重点地区、重点场所、重点环节的禽流感防控工作。

2013-2020年广西重点种鸡场禽白血病净化效果分析

按照检测-淘汰-分群-再检测-再淘汰的原则,建立“生物安全+病原监测+淘汰”模式对2013—2020年广西11家重点种鸡场的种公鸡、种母鸡、育成鸡和雏鸡采集精液、蛋清、泄殖腔拭子、胎粪等样品进行禽白血病病原检测;公鸡和母鸡同时采集血浆蛋白进行禽白血病病毒(ALV)分离。通过多方式联合净化禽白血病,ALV阳性率逐年下降,净化效果非常显著。其中公鸡精液中ALV阳性率由2013年的7.45%下降到2020年的0.14%,母鸡蛋清样本ALV阳性率由2013年12.32%下降到2020年0.23%,雏鸡胎粪ALV阳性率由2018年3.60%下降到2020年0.47%。公鸡血浆蛋白病毒检出率由2013年的3.46%下降到2020年的0.78%,母鸡血浆蛋白病毒检出率由2013年的2.22%下降到2020年的0.20%。可以看出ALV净化效果非常显著,说明所建立的禽白血病净化方法在广西行之有效。

不同禽源副鸡禽杆菌的人工交叉致病试验

为探讨鸡源和鹅源副鸡禽杆菌(Avibacterium paragallinarum,Apg)对鸡、鹅的跨禽种感染致病力情况,试验将3株鹅源Apg和4株鸡源Apg培养物经鼻窦腔接种60日龄鸡和鹅,观察接种禽的临床症状并进行表征评分。通过组织病理学检查、细菌分离培养和Apg种特异性PCR鉴定,研究鸡源和鹅源Apg对不同宿主的致病性情况。结果显示:鸡源和鹅源Apg均可导致鸡、鹅出现典型症状与病变,且对原宿主禽种致病性高于非原宿主禽种;发病鸡、鹅的病理变化相似,以面部皮下和鼻窦黏膜水肿、充血出血、纤维素性渗出,鼻甲骨变形为特征;发病鹅和鸡组织病理变化相似,鼻窦黏膜与鼻甲黏膜出现大量炎性细胞浸润,黏膜上皮水肿、坏死、崩解脱落,固有层结构疏松,局部可见纤维结缔组织增生;3株鸡源Apg接种鸡试验组能从鼻窦部、肝脏和脾脏中重新分离到接种菌,而接种鹅试验组仅从鼻窦部分离接种菌,未能从其他组织中分离到。研究表明,鸡源和鹅源Apg均可感染鸡或鹅并引起发病,但在致病程度上以本禽源菌株强于非本禽源菌株。