Serological evidence of chicken anaemia virus infection in Nigerian indigenous chickens

Serum samples from 20 out of 180 (11.1%) apparently healthy Nigerian indigenous chickens were negative for antibodies against chicken anaemia virus using the enzyme-linked immunosorbent assay (ELISA). Of the 160 positive sera (88.9%), 12 (7.5%) had titres ranging from 1500-3000, 46 (28.8%) had titres from 3000-5000 while 102 (63.8%) had titres between 5000-11000. The overall mean titre value was 5845 +/- 2402. This appears to be evidence of a natural outbreak of the infection since the chickens had no history of vaccination against any poultry disease.     

山东省鸡传染性贫血流行病学调查

本文对山东省12个地市58个鸡群传染性贫血的流行情况进行了调查,共检测了368份血清样品,蛋鸡群、肉鸡群和种鸡群的鸡传染性贫血病毒(CAV)ELISA抗体检出率分别为91.7%、77.6%和84.78%,平均抗体阳性率为83.2%,结果表明近几年山东省鸡群中CAV感染相当普遍,而且蛋鸡和种鸡抗体阳性率明显高于肉鸡群。     

鸡传染性贫血病毒研究进展

对鸡传染性贫血病毒的理化特性、基因组结构及其编码蛋白、复制、致病性和免疫预防与控制措施等进行了概述。     

1株鸡传染性贫血病毒野毒株对不同日龄SPF鸡的致病性

从山东省某商品代肉鸡场表现生长迟缓的20日龄病鸡群分离到1株鸡传染性贫血病毒(CAV)SDLY08株,通过口服和肌肉注射2种途径分别感染1,7,21日龄SPF鸡,12d后检测CAV对SPF鸡体质量、免疫器官和血液指标的影响。结果表明,于3个不同日龄感染后12d,SDLY08株均可导致增重减缓,胸腺显著萎缩,脾脏肿大,同时还可引起白细胞、红细胞数及红细胞压积的显著减少。且1日龄和7日龄鸡易感性大于21日龄鸡,肌肉注射比口服感染组的致病性更强。     

Isolation of chicken anaemia virus from broiler chickens.

Chicken anaemia virus (CAV) infection was demonstrated, by both serology and virus isolation, in 1- to 6-week-old broiler chickens originated from various parent flocks in Hungary. Total losses in the broiler flocks were estimated at 7 to 8% and about 25% of the chickens failed to reach target body mass by the 7th week of life. The clinical signs, postmortem lesions and histopathological changes of the affected chickens were similar to those of naturally occurring CAV-induced infectious anaemia of young chickens. In MDCC-MSB1 cell cultures, a chloroform-resistant virus smaller than 50 nm in diameter, resistant to heating at 70 degrees C for 30 min, and antigenically very closely related to the Cux-1 strain of CAV was isolated from the liver of naturally diseased broilers. This virus isolate was designated the Bia strain of CAV. Inoculation of susceptible 1-day-old SPF chicks with a CAV-positive liver extract from naturally diseased broilers caused pathological changes characteristic of CAV infection, namely impaired growth, severe anaemia with atrophy of the bone marrow, marked atrophy of the lymphoid organs and petechial haemorrhages throughout the body. A quite similar pathological syndrome was also induced by inoculation of 1-day-old SPF chicks with the MDCC-MSB1 cell-culture-propagated new Bia strain of CAV. The CAV was successfully reisolated from the livers of experimentally inoculated birds, and antibodies to the reference Cux-1 strain of CAV were also demonstrated by the indirect immunofluorescence test in sera of naturally diseased and experimentally inoculated chickens. No antibodies were found against infectious bursal disease virus, reticuloendotheliosis virus, Marek's disease herpesvirus as well as avian adenoviruses and reoviruses. The reported disease of young broiler chickens was associated with natural infection of a new isolate of CAV. On the basis of its physicochemical, antigenic and pathogenic characteristics, this virus is similar to other strains of CAV isolated from chickens in other countries.     

Persistent infection with chicken anaemia virus and some effects of highly virulent infectious bursal disease virus infection on its persistency

Chicken anaemia virus (CAV) infectivity and the effect of highly virulent infectious bursal disease virus (hv IBDV) infection on CAV's infectivity were examined in chickens inoculated with CAV or inoculated dually with CAV and hv IBDV. Five chickens inoculated dually with hv IBDV at 35 days old and then with CAV at 40 days old exhibited no clinical signs of disease, but showed atrophic bursae of Fabricius when necropsied 4 weeks later. Upon examining the chickens at 7 days postinoculation (dpi) with CAV, it was found that hv IBDV infection had inhibited production of virus neutralising (VN) antibody to CAV, and that it was possible to recover CAV from plasma of these chickens. Although VN antibody to CAV appeared after 14 dpi, CAV was recovered from blood cells (BC s) at high titres ranging from 10(2.5)to 10(5.5)TCID(50)/0.1 ml, 7 to 28 dpi in IBDV -induced immunosuppressed chickens. In addition, CAV was sporadically recovered, using rectal swabs, from the dually inoculated chickens at low titers, ranging from 10(1.0)to 10(2. 0)TCID(50)/0.1 ml). In contrast, although CAV was recovered from BC s in most of the chickens inoculated with CAV alone, the titers were lower (10(1.0)to 10(2.5)TCID(50)/0.1 ml). No CAV was detected from the rectal swabs of these chickens. The results of virus recovery were confirmed by polymerase chain reaction. This study first examined the persistency of CAV in BC s and the effective enhancement of primary CAV infection as a result of immunosuppression caused by hv IBDV infection.     

Isolation of chicken anaemia virus from broiler chickens in New Zealand

Chicken anaemia virus was isolated for the first time in New Zealand from the New Zealand domestic chicken population. The virus was recovered from diseased birds in five separate flocks of broiler chickens aged between 14 and 33 days of age. Six isolates were obtained from bone marrow and lymphoid tissues using the MDCC-MSB1 cell line derived from Marek's disease lymphoma. All isolates were resistant to chloroform and survived exposure to 70 degrees C for 5 minutes. The main clinical features consistently associated with the disease outbreaks were increased mortality, yolk sac infections, sub-cutaneous haemorrhages and atrophy of the thymus. Fungal pneumonia occurred in two flocks, and gangrenous dermatitis as a result of bacterial infection in another flock. Microscopic examination showed atrophy of the thymus, reduced medullary haematopoiesis and inflammation resulting from secondary infections.     

免疫失败种鸡群中鸡贫血病毒感染的检测

鸡贫血病毒 (chick anaemia virus,CAV)是鸡传染性贫血的病原 ,它是圆环病毒科的代表成员 ,为单股负链环状 DNA病毒 ,基因组全长约为 2 3 0 0bp[1,2 ]。 CAV可引起雏鸡的再生障碍性贫血和全身淋巴组织萎缩 ,尤其是胸腺萎缩 [3 ]。 1周龄以内的雏鸡 CAV感染后易导致死亡 ,而 1周     

禽网状内皮组织增生病病毒和呼肠孤病毒感染SPF鸡对IFN-γ产生的影响

1日龄SPF鸡分别接种禽网状内皮组织增生病病毒（REV）、禽呼肠孤病毒（ARV）和REV＋ARV,于感染后3、5、46 d采集脾细胞做脾淋巴细胞培养并采用双抗体夹心ELISA法检测IFN-γ水平。结果表明,与对照相比,鸡感染REV后脾淋巴细胞IFN-γ的分泌水平显著升高。感染后5 d,REV单独感染引起IFN-γ8倍的增长,达到峰值,然后逐渐下降。ARV单独感染引起IFN-γ2倍的增长。REV和ARV共感染鸡脾淋巴细胞IFN-γ的分泌量增长了3倍。至感染后46 d,共感染和REV单独感染的IFN-γ水平与对照组相比仍然差异显著,ARV单独感染与对照组相比差异不再显著。     

Reduced mucosal injury of SPF chickens by mast cell stabilization after infection with very virulent infectious bursal disease virus

Recent studies here have demonstrated that increased mast cell populations and tryptase activity contribute to lesion formation in regions of immune organs in special-pathogen-free chickens after infection with very virulent infectious bursal disease virus (vvIBDV). Mast cells and their mediators have been implicated in acute inflammatory injury after vvIBDV infection, but their precise role in this process remains elusive. In this study, the role of mast cells in the vvIBDV infection process was examined using ketotifen, a mast cell membrane stabilizer. On days 1, 2, and 3 postinfection, the bursa of Fabricius (BFs) were collected to quantify mast cells, tryptase and histamine contents by cytochemistry, immunohistochemistry and fluorospectrophotometry analyses, respectively. The results showed that the mast cell populations, tryptase expression, and histamine released increased significantly in the BFs (p < 0.01) of infected birds compared to controls, and acute inflammatory responses were observed in the former. In contrast, in infected chickens pretreated with ketotifen, mast cells, tryptase, and histamine were markedly decreased (p < 0.01) and probably as a result, the BFs remitted significantly. The overall results suggest that mast cells are positively involved in BF injury induced by vvIBDV infection. Inhibition of mast cell degranulation and concurrent mediator release may represent a novel strategy to modulate this process. This study, thus, advances the understanding of the acute inflammatory injury mechanisms triggered by vvIBDV infection and the contribution of mast cell activity in this process.     

Effects of reticuloendotheliosis virus and Marek's disease virus infection and co-infection on IFN-gamma production in SPF chickens

Two experiments were used to examine the potential role of IFN-gamma in chickens infected with reticuloendotheliosis virus (REV) and Marek's disease virus (MDV). First, chickens were infected with REV and/or MDV at 5 days of age and examined from 3 to 50 days post-infection (dpi). In REV+MDV co-infection chickens, IFN-gamma ELISA demonstrated a 3-fold increase at 7 dpi compared to the controls, while REV alone caused a 5-fold increase, the IFN-gamma levels peaked, and then gradually decreased. IFN-gamma levels significantly decreased in MDV infection at 3 dpi and 15 dpi. Second, experiments were designed to determine the effects of different viruses and ConA on IFN-gamma production. For REV- or MDV-infected chickens, the IFN-gamma levels decreased slightly after adding ConA. This is the first report of IFN-gamma production in SPF chickens infected with REV and MDV measured by directly quantitative method.     

PCR和斑点杂交检测实验感染雏鸡体内鸡传染性贫血病毒的动态分布

鸡传染性贫血病毒(CIAV)自1979年日本学者Yuasa等首先分离以来，世界各地均有报道。该病原以致鸡再生障碍性贫血和淋巴组织萎缩为特征，从而导致免疫抑制，严重影响机体对疫苗的免疫反应，为危害养禽业的重要病原之一。     

鸡传染性支气管病毒ZZ2004株致SPF感染鸡小肠损伤的病理与超微病变研究

为研究鸡传染性支气管炎病毒(IBV) ZZ2004株引起鸡生长缓慢的发病机理,本实验将100只7日龄SPF雏鸡平均分为两组.实验组经口服病毒进行感染,对照组口服生理盐水,通过临床检查、病理学检查及超微病变观察进行研究.病理解剖学检查表明,实验组鸡各肠段有不同程度卡他性出血性炎性变化.病理组织学显示,小肠绒毛变短,上皮细胞脱落,固有层内炎性细胞增多.扫描电镜观察表明,肠绒毛的游离端常断裂,固有层裸露,在肠上皮细胞之间有大量杯状细胞的开口,并见大块状的分泌物渗出.透射电镜检查显示,残存的肠上皮细胞的微绒毛严重破坏;粗面内质网脱颗粒,滑面内质网明显扩张,呈囊状或泡状,在内质网中出现大量病毒颗粒;核周隙扩张,在核质中能够检出成熟的病毒颗粒.本研究结果表明:IBV ZZ2004株可以在肠上皮细胞中增殖,引起肠的吸收上皮和肠绒毛的一系列退行性病变,从而导致感染鸡代谢障碍,生长缓慢.     

Experimental cryptosporidiosis and infectious bursal disease virus infection of specific-pathogen-free chickens

Specific-pathogen-free chickens orally inoculated at 4 days of age with a moderately pathogenic vaccine strain of infectious bursal disease virus (IBDV) and/or at 5 days of age with Cryptosporidium baileyi oocysts remained free of overt clinical signs throughout a 16-day period postinoculation (PI). The prepatency period for C. baileyi oocyst shedding was shorter in chickens receiving higher numbers of oocysts, but once shedding was detected, there were no obvious differences in shedding patterns among groups receiving 10(3) through 10(6) oocysts. On days 8 and 16 PI, cryptosporidia were located primarily in the bursae of Fabricius. IBDV exposure was associated with bursal follicle atrophy, whereas C. baileyi infection resulted in bursal epithelial hypertrophy and hyperplasia, mild follicle atrophy, and heterophil infiltration of the bursal mucosa. Examination of experimental groups of 30 birds each indicated that concurrent infection with both agents resulted in more severe bursal lesions, more infected birds, and greater numbers of cryptosporidia in infected tissues. At the termination of the trial, 16 days PI, Cryptosporidium infection was associated with a 6% decrease in mean body weight compared with controls.     

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.