Seroprevalence of avian influenza virus, infectious bronchitis virus, reovirus, avian pneumovirus, infectious laryngotracheitis virus, and avian leukosis virus in Nigerian poultry

Eight poultry farms in Nigeria, including chickens from nine breeder, 14 broiler, 28 pullet, 11 layer, and three cockerel flocks, were tested for antibody seroprevalence to the following poultry viruses of potential economic importance: infectious bronchitis virus (IBV), avian reovirus, avian pneumovirus (APV), infectious laryngotracheitis virus (ILTV), avian influenza virus (AIV), and avian leukosis virus (ALV). Serum samples were collected between 1999 and 2004 and were tested for antibodies using commercial enzyme-linked immunosorbent assay (ELISA) kits. Seroprevalence was very high for IBV (84%); intermediate for reovirus (41%), APV (40%), and ILTV (20%); and very low for ALV (<5%) antibodies. By commercial ELISA, the seroprevalence of antibodies against AIV was, in some flocks, up to 63%. However, more specific assays did not confirm AIV antibodies, indicating that all flocks tested were free of avian influenza antibodies. Birds seemed to be first infected by IBV (at about 7 wk of age), then by reovirus at 12 wk, before they became infected by APV (week 25) and ILTV (week 30). This is the first report of serological evidence of the above viruses in West Africa. Further studies are necessary to assess economic losses due to these avian viruses and the costs and benefits of countermeasures.     

Effects of blood sample mishandling on ELISA results for infectious bronchitis virus, avian encephalomyelitis virus and chicken anaemia virus

This study determined the effect of sample mishandling on the performance of ELISAs for detection of antibodies against infectious bronchitis virus (IBV), avian encephalomyelitis virus (AEV) and chicken anaemia virus (CAV) in the serum of chickens. The effects of five different sample mishandling treatments were assessed: heat treatment, repetitive freezing and thawing and three levels of severity of haemolysis. These mishandling treatments simulated different conditions that might occur during routine blood collection, transport or storage in a clinical practice setting. Each mishandling treatment was experimentally applied under laboratory conditions and then samples were assayed for antibodies against IBV, AEV and CAV using commercial ELISA kits. Severe haemolysis had the most consistent detrimental effect on ELISA performance, producing results that were significantly different from the reference standard in all three ELISAs, although the direction of the effect varied (less positive for the IBV and CAV assays; more positive for the AEV assay). Moderate levels of haemolysis had a similar, but less consistent, effect to that of severe haemolysis, producing results that were significantly different from the reference standard only for the IBV (less positive) and AEV (more positive) ELISAs. Repetitive freeze-thawing also produced a significant effect on ELISA results for IBV (less positive) and AEV (more positive). The IBV ELISA appeared to be most susceptible to the effects of serum maltreatment. The findings from this study suggest that unpredictable variation in the results of ELISAs can occur due to different sample mishandling treatments.     

鸡肾型传染性支气管炎病毒组织嗜性的研究

本研究用鸡肾型传染性支气管炎病毒 (肾型 IBV) C90 0 1株人工感染 14日龄 SPF鸡 ,于接种后定期采集病鸡的各组织器官制备成石蜡切片 ,用建立的检测石蜡切片中肾型 IB病毒的免疫酶组化染色技术 ,对人工感染肾型传染性支气管炎 (肾型 IB)鸡发病后病毒的组织器官亲嗜性和动态分布规律进行了研究。结果表明 ,肾型 IBV在胞浆内复制 ,主要亲嗜气管黏膜的上皮细胞和固有层腺体细胞、肺各级支气管上皮细胞以及肺房和呼吸性毛细管上皮细胞、气囊上皮细胞、肾和输尿管上皮细胞、消化道上皮和固有层腺体细胞、肝小叶间胆管上皮细胞、胰腺导管上皮细胞和腺泡上皮细胞、法氏囊淋巴滤泡髓质区淋巴细胞和网状细胞、胸腺小叶髓质区淋巴细胞和网状细胞、脾小体淋巴细胞、盲肠扁桃体弥散性淋巴组织的淋巴细胞以及心肌细胞 ,病毒出现的先后顺序为气管、肺脏、肾脏、输尿管 ,消化道、法氏囊、肝脏、胰脏、胸腺和气囊 ,盲肠扁桃体 ,脾脏 ,心肌。病毒在肾脏和输尿管持续 2 0天 ,气管为 13天 ,消化道和法氏囊为 11天 ,肝脏、胰脏和肺为 10天 ,胸腺为 6天 ,气囊为 5天 ,盲肠扁桃体、脾脏、心肌呈一过性感染     

鸡肾型传染性支气管炎病毒的分离鉴定

通过鸡胚接种盲传,从重庆某地疑似鸡肾型传染性支气管炎的发病鸡群中,分离到一株病毒,该病毒能导致鸡胚出现侏儒胚。用本病毒对10日龄雏鸡做回归实验,可使试验鸡出现典型的花斑肾。试验应用反转录-聚合酶链式反应(RT—PCR)技术扩增出了该病毒的特异性基因M和N,从分子学角度进一步证实了引起鸡群死亡的病毒为鸡传染性支气管炎病毒。     

鸡传染性支气管炎病毒基因型与血清型相关性初步研究

为研究鸡传染性支气管炎病毒(IBV)基因型与血清型之间的相关性,本研究以国内不同地区的17株IBV分离株、2株疫苗株(M41、W93)和1株强毒株(X株)为研究对象,经RT-PCR扩增获得20株IBV的S1基因并进行测序.将其分别与GenBank中的20株国内外参考IBV株的S1基因进行序列比较,绘制S1基因系统进化树...     

Recent studies on the enterotropic strain of avian infectious bronchitis virus

Avian infectious bronchitis (AIB) is an economically important disease of chickens. Recent studies have revealed enterotropism by at least one strain of AIB virus with pathological lesions in parts of the gut. This review highlights the findings of the studies so far made on this enterotropic strain of AIB virus.     

Epididymal stone formation and decreased sperm production in roosters vaccinated with a killed strain of avian infectious bronchitis virus

Our objective was to determine if vaccination with killed avian infectious bronchitis virus (AIBV) causes epididymal calcium stones in the rooster as is seen following vaccination with live attenuated AIBV. Specific-pathogen-free roosters were divided into three groups: nonvaccinated (NONVAC), live attenuated AIBV-vaccinated (LVAC), and killed AIBV-vaccinated (KVAC) groups. Roosters were vaccinated at 2, 6, 10, and 14 wk of age and the epididymal region was observed at 27 wk of age. Epididymal stones were present in 13% of NONVAC, 50% of KVAC, and 64% of LVAC roosters. Histologically, immune cells were seen in the interstitium of efferent ductules containing stones. We conclude that use of a killed vaccine does not reduce the incidence of epididymal stones.     

嗜肾型传染性支气管炎病毒X株的分离和致弱培育

利用鸡胚分离法从发生肾变病型传染性支气管炎的病鸡分离嗜肾型传染性支气管炎病毒X株,该病毒株能引起鸡胚发育受阻,鸡胚和雏鸡肾脏肿大、输尿管尿酸盐沉积,能被传染性支气管炎病毒M型血清部分中和,初步研究表明是一个新的毒株。通过SPF鸡胚连续传代,获得了嗜肾型传染性支气管炎弱毒疫苗毒株X 93。结果显示,X株经过鸡胚传代,对鸡胚的致死率由原代的0上升到90代的82%;在每0.1 mL鸡胚中的病毒含量由原代的10^5.0E ID50上升到90代的10^7.8E ID50;对3日龄SPF雏鸡的致病率和致死率分别由40代时的70.0%和40.0%下降到90代时的0值;与X 93接种鸡一同饲养的实验鸡全部健康存活;X 93回归雏鸡连传5代,未见毒力返强现象。     

Cross-immunity in chickens using seven isolates of avian infectious bronchitis virus

Groups of 75 chickens were each infected with one of 7 isolates of infectious bronchitis virus (Mass 41, Holland 52, SE 17, Ark 99, Clark 333, JMK, and Florida). Following recovery, they were challenged along with susceptible controls to the homologous and 6 heterologous isolates. Cross-immunity was determined by virus recovery 4 or 5 days post-challenge. Challenge with the homologous isolate resulted in 90-100% protection. Challenge with heterologous isolates gave variable results and an overall average resistance of 38%. The SE-17-recovered chickens had a 50% protection, whereas the Holland-52-recovered chickens ahd a 13.3% protection.     

Vaccination against infectious bronchitis in young chickens--carriers or not of maternal antibodies

The immunity to infectious bronchitis afforded by spray vaccination of mycoplasma free two days-old broilers with maternal antibodies to infectious bronchitis virus was tested by comparing zootechnical scores, clinical signs, macroscopical and microscopical changes, frequency of infectious bronchitis virus isolation following challenge at one, three and five weeks of age in vaccinated, unvaccinated, challenged and unchallenged birds. This vaccination gave a very good protection to infectious bronchitis for the most part of broiler economical life; growth delays were especially avoided. However, vaccinated and unvaccinated one-week-old birds were not protected enough. No correlation was observed between haemagglutinating antibodies titres and protection. At last this vaccination caused a notable reaction in specific pathogen free control birds of the same age.     

Effect of active immunization against GnRH on testosterone concentration,libido and sperm quality in mature AI boars

Background

The aim of the present study was to investigate the efficacy of the Improvac on testosterone concentration in blood serum, sexual behavior and sperm quality in matured AI boars. A total of nine Danish Landrace AI boars were included in the analysis.

Methods

The trial period lasted for 15 weeks and was divided into four periods: Control period: three weeks before vaccination; Period I – four weeks after first vaccination; Period II – four weeks after second vaccination, Period III – four weeks after third vaccination. Blood and sperm samples were collected at weekly intervals. Freshly collected sperm samples were analyzed.

Results

Testosterone concentration correlated with libido (r = 0.531; p < 0.001), volume of ejaculate (r = 0.324; p < 0.001) and the percentage of morphologically normal spermatozoa (r = 0.207; p < 0.05). Testosterone concentration rised significantly (p < 0.05) in 5–6 week of trial, e. i. after the first dose of Improvac and after this peak the level of testosterone further progressively decreased (p < 0.05).

Conclusions

Results from this study indicate that active immunization of sexually matured boars against GnRH has negative impact on testosterone concentration, sexual behavior, volume of ejaculate and total number of normal spermatozoa in ejaculate.     

鸡新城疫、传染性支气管炎和禽流感(H9)联合免疫血清学效力与攻毒保护关系

在预防鸡新城疫、传染性支气管炎和低致病性H9亚型禽流感这3种禽类传染病时,临床上常常使用针对这3种疾病的三联疫苗进行预防。为了研究抗原量和它们的HI抗体以及与攻毒保护之间的关系,我们进行了相关研究,结果表明:在一定程度上,每种抗原的量均与HI抗体呈正比;HI抗体的高低与攻毒保护之间呈正比例关系;当传染性支气管炎的HI抗体是初免的3倍以上时,均能对传染性支气管炎病毒强毒的攻击产生较好的保护。     

Emergence of novel strains of avian infectious bronchitis virus in Sweden

Infectious bronchitis virus (IBV) causes avian infectious bronchitis, an important disease that produces severe economic losses in the poultry industry worldwide. Recent IBV infections in Sweden have been associated with poor growth in broilers, drop in egg production and thin egg shells in layers. The complete spike gene of selected isolates from IBV cases was amplified and sequenced using conventional RT-PCR. Nucleotide and amino acid sequence comparisons have shown that the recent isolates bear 98.97% genetic similarity with strains of the QX-like genotype. The phylogenetic analysis revealed that strains predominant in the nineties, which were of the Massachusetts type, have been replaced by D388/QX-like strains, however the evolutionary link could not be established. The homology between the two genotypes was 79 and 81%. Remarkably, a strong positive selection pressure was determined, mostly involving the S1 subunit of the S gene. This strong selective pressure resulted in recombination events, insertions and deletions in the S gene. Two new isolates generated from recombination were found with nucleotide sequence diverging 1.7-2.4% from the D388/QX-like branch, indicating the emergence of a new lineage. The study demonstrates a constant evolution of IBV that might be in relation to increased poultry farming, trade and vaccine pressure. The findings underscore the importance of continuous monitoring to control spread of infections, as well as to timely adjust diagnostic methods, molecular epidemiological studies, development and use of vaccines that are adapted to the changing disease scenario.     

一株鸡肾型传染性支气管炎病毒的分离与鉴定

从山东某鸡场疑似肾型传染性支气管炎病死鸡的肾脏中分离到一株病毒,经SPF鸡胚连续传代、血凝试验、鸡新城疫干扰试验、鸡胚矮小化试验、RT—PCR鉴定和动物回归试验,初步确定该病毒为肾型传染性支气管炎病毒,并命名为SD1105株。