Serologic monitoring of a broiler breeder flock previously affected by inclusion body hepatitis and testing of the progeny for vertical transmission of fowl adenoviruses

The increasing number of clinical cases of inclusion body hepatitis (IBH) associated with fowl adenoviruses (FAdVs) is a growing concern in different parts of the world, including Canada. After an outbreak of IBH in a 10-d-old pullet broiler breeder flock, we serologically monitored the flock from 8 to 46 wk of age, using the agar gel precipitation test (AGPT) offered by diagnostic laboratories and an FAdV group-specific enzyme-linked immunosorbemt assay (ELISA) developed earlier. In addition, we tested 1-d-old progeny for possible vertical transmission of FAdV when the breeder flock approached the peak of egg production by performing virus isolation and polymerase chain reaction (PCR) procedures on target organs. As in previous studies comparing the 2 tests, ELISA was more sensitive than AGPT. With ELISA, a few birds had weakly positive results at 8 wk of age, and all the birds had strongly positive results from 12 wk of age until the end of the study. This group-specific ELISA is therefore a sensitive and practical way to monitor FAdV antibodies in commercial flocks. None of the 1-d-old chicks tested were positive by PCR, nor was FAdV isolated from the same tissues, indicating an absence of transmission of infectious virus to the progeny. The lack of virus production and transmission could be due to the presence of high antibody titers in the layers.     

Application of high-resolution melting curve analysis for typing of fowl adenoviruses in field cases of inclusion body hepatitis

Objective Fowl adenoviruses (FAdVs) cause inclusion body hepatitis (IBH) in chickens. In this study, clinical cases of IBH from Australian broiler flocks were screened for the presence and genotype of FAdVs. Methods Twenty‐six IBH cases from commercial poultry farms were screened. Polymerase chain reaction (PCR) coupled with high‐resolution melt (HRM) curve analysis (PCR/HRM genotyping) was used to determine the presence and genotype of FAdVs. For comparison, field isolates were also assessed by virus microneutralisation and nucleotide sequence analysis of the hexon loop 1 (Hex L1) gene. PCR detection of chicken anaemia virus (CAV) and infectious bursal disease virus (IBDV) was also employed. Results FAdV‐8b and FAdV‐11 were identified in 13 cases each. In one case, FAdV‐1 was also identified. Cross‐neutralisation was observed between the FAdV‐11 field strain and the reference FAdV‐2 and 11 antisera, a result also seen with the type 2 and 11 reference FAdVs. Field strains 1 and 8b were neutralised only by their respective type antisera. The FAdV‐8b field strain was identical to the Australian FAdV vaccine strain (type 8b) in the Hex L1 region. The Hex L1 sequence of the FAdV‐11 field strain had the highest identity to FAdV‐11 (93.2%) and FAdV‐2 (92.7%) reference strains. In the five cases tested for CAV and IBDV, neither virus was detected. The evidence suggested the presence of sufficient antibodies against CAV and IBD in the parent flocks and there was no indication of immunosuppression caused by these viruses. Conclusion These results indicate that PCR/HRM genotyping is a reliable diagnostic method for FAdV identification and is more rapid than virus neutralisation and direct sequence analysis. Furthermore, they suggest that IBH in Australian broiler flocks is a primary disease resulting from two alternative FAdV strains from different species.     

The fowl adenovirus (Fadv-11) outbreak in Iranian broiler chicken farms: The first full genome characterization and phylogenetic analysis

Fowl adenoviruses D and E (FAdV-D and E) can cause inclusion body hepatitis (IBH) in commercial chicken flocks. Recently, IBH outbreaks have been increasingly reported in different regions of Iran, particularly in broiler farms. The present study was conducted to perform, for the first time, a complete genome characterization of a FAdV isolate from an IBH outbreak in Iran. Briefly, liver samples were collected from affected broiler flocks and following viral DNA extraction and confirming by PCR technique; one positive sample was selected from an affected flock to conduct a complete genome sequencing. The current FAdV, named "Fowl_Adenovirus_D_isolate_iran/UT-Kiaee_2018", was placed into FAdV-11 serotype (D species). According to the complete genome sequence analysis, UT-Kiaee had high homology with Chinese and Canadian FAdV. The partial sequence of the hexon gene revealed that UT-Kiaee shared 100% identity with previous Iranian FAdVs. The present study was the first to report full genome FAdV in Iran and complete the puzzle of molecular epidemiology of FAdV in Iran through determining the possible origin of Iranian FAdvs, which are the causative agents of recent IBH outbreaks in Iran.     

Partial sequence of the DNA-dependent DNA polymerase gene of fowl adenoviruses: a reference panel for a general diagnostic PCR in poultry

Adenoviruses are frequent infectious agents in different poultry species. The traditional, serological typing of new isolates by virus neutralisation tests is now in transition to be replaced by PCR and sequencing. The first PCRs, recommended for the detection of adenoviruses, had been designed to target the gene of the major capsid protein, the hexon. In birds, members of three different genera of the family Adenoviridae may occur. Accordingly, three specific hexon PCRs had to be elaborated for the detection of adenoviruses in poultry. A significantly more sensitive PCR, targeting the viral DNA-dependent DNA polymerase gene, has been described recently. This method proved to be an efficient alternative for the general detection of adenoviruses irrespective of their genus affiliation. Fowl adenoviruses (FAdVs), isolated from chicken to date, comprise twelve serotypes classified into five virus species (FAdV-A to E). The polymerase gene sequence has been determined yet only from three FAdV types representing three species. In the present work, the panel of polymerase gene sequences was completed with those of the rest of FAdVs. The newly determined sequences will facilitate the identification of new FAdV isolates as an existing species or as a putative new FAdV. Once the polymerase sequence is known, more specific PCRs for the amplification of the hexon and other genes can be designed and performed according to the preliminary species classification.     

Ⅰ群禽腺病毒套式PCR检测方法的建立与应用

本研究根据GenBank发表的Ⅰ群禽腺病毒(Fowl adenovirus,FAdV)基因序列,设计了2对通用检测引物,通过反应体系和条件优化,建立了Ⅰ群禽腺病毒套式PCR检测方法。通过灵敏性检测、特异性试验以及对临床病料中FAdV检测验证实用性与可靠性。建立的套式PCR检测方法灵敏度为3.12×10-6 ng/μL;特异性试验证实该方法仅能从FAdV参考阳性株扩增出750 bp的预期目的条带,其他5种常见禽病毒均为阴性。结果表明,本研究成功建立了一种灵敏度高、特异性好的检测Ⅰ群禽腺病毒通用套式PCR方法,为临床FAdV感染的快速准确诊断提供了技术手段。     

Pathotypic and molecular characterization of a fowl adenovirus associated with inclusion body hepatitis in Saskatchewan chickens

Inclusion body hepatitis (IBH) is one of the major global disease problems, causing significant economic losses to poultry industry of the United States and Canada. The disease is characterized by its sudden onset and high mortalities. Amongst different serotypes of fowl adenoviruses (FAdVs) associated with IBH, serotype 8 of group I FAdV has been isolated from majority of IBH cases. In present studies, we isolated a FAdV from morbid liver of a 17-day-old broiler from a Saskatchewan broiler farm. This newly isolated virus was designated as IBHV(SK). However, based on the sequence analysis of the L1 region of the hexon gene, the IBHV(SK) may be classified as FAdV 8b strain 764. These studies describe for the first time the complete hexon gene sequence of FAdV serotype 8b. Experimental infection of 2-day-old (n = 48) and 2-wk-old (n = 56) chicks caused 83% and 43% mortalities, respectively. Determination of the complete hexon gene sequence of IBHV(SK) with establishment of a disease model in chickens will facilitate the development of type-specific diagnostic reagents and assays for the evaluation of potential experimental vaccines against pathogenic FAdV infections.     

Application of the polymerase chain reaction to detect fowl adenoviruses.

The possibility of using the polymerase chain reaction (PCR) for the detection of fowl adenoviruses (FAdV) was tested. The optimal reaction parameters were evaluated and defined for purified genomic DNA of type 8 fowl adenovirus (FAdV-8), and then the same conditions were applied for nucleic acid extracted from infected cells. One hundred picograms of purified viral DNA, or 250 FAdV-8-infected cells, were detected by ethidium bromide staining of the PCR products in agarose gels. The sensitivity was increased to 10 pg purified viral DNA, or 25 infected cells, when the PCR products were hybridized with a specific labeled probe. Several field isolates of FAdV and the CELO virus (FAdV serotype 1) could be amplified by the same primers and conditions, but the size of the amplicons was smaller than that for the FAdV-8 PCR product. Other avian viruses and uninfected cell cultures tested negative.     

Isolation and Molecular Characterization of Fowl Adenovirus and Avian Reovirus from Breeder Chickens in Japan in 2019–2021

Fowl adenoviruses (FAdVs) and avian reoviruses (ARVs) are ubiquitous in poultry farms and most of them are not pathogenic, yet often cause damage to chicks. A total of 104 chicken fecal samples were collected from 7 farms of breeder chickens (layers and broilers) in Japan from 2019 to 2021, and yielded 26 FAdV plus 14 ARV isolates. By sequencing, FAdV isolates were classified as FAdV-1, 5 and 8b. ARV isolates were classified as genotype II, IV and V. These results suggest that FAdVs and ARVs are resident in the breeder chicken farms in Japan.     

Identification and virulence characterization of fowl adenoviruses in Korea

Since 2007, 55 adenovirus strains have been isolated from commercial chicken flocks in Korea and have been identified and the pathogenicity of these isolates was confirmed in specific-pathogen-free chickens of different age. Based on sequencing analysis of the hexon gene, 55 FAdV isolates were genetically related to the IBH-2A strain of FAdV3 (4 isolates, 99.2% to 100%), the KR5 strain of FAdV4 (22 isolates, 97.9% to 99.2%), the 764 strain of FAdV9 (11 isolates, 99.1% to 99.3%), and the 1047 strain of FAdV11 (18 isolates, > 99%). Experimental infections with four serotypes of FAdV resulted in high mortality of 18-day-old chicken embryos and 1-day-old chicks with marked liver necrosis similar to those observed in the natural outbreaks. Notably, specific hydropericardium was observed in chicks challenged with the K531 strain (serotype 4). However, 3-wk-old chickens challenged with FAdVs, regardless of serotype, did not show any clinical signs or mortality except histologic lesions of focal hepatocytic necrosis with mild lymphocytic infiltration. The results indicate that four FAdV serotypes (3, 4, 9, and 11) are the dominant serotypes of FAdVs in the Korea and are pathogenic enough to cause clinical disease in young chicks. The present investigation provides important information on the epidemiology and pathogenesis of FAdVs and highlights the importance of control strategies against FAdV infection in Korea.     

Fowl adenoviruses isolated from chickens with inclusion body hepatitis in Japan, 2009-2010

Nine fowl adenoviruses (FAdVs) isolated from chickens with inclusion body hepatitis (IBH) in Japan from 2009 to 2010 were characterized serologically and genetically. These isolates were all neutralized by antisera against the SR-48 strain (FAdV-2). Phylogenetic analysis based on the part of the hexon gene that included the L1 region revealed that all isolates were almost identical except one isolate in 2009. This suggests a common ancestor for the FAdVs obtained from chickens with IBH in Japan in 2010.     

Gene Analysis of Penton Protein of 12 Serotypes of Fowl Adenovirus

In order to understand the genetic evolution of Penton protein of fowl adenovirus(FAdV),the specific primers of Penton were designed on the basis of published sequences of different genotypes on GenBank.Then Penton gene of 12 serotypes were amplified by PCR and constructed into pEASY-Blunt Simple Cloning Vector for sequencing.The nucleotide sequences of Penton protein of 12 serotypes were analyzed and compared with the nucleotide sequences of standard strains published on NCBI by ClustalW method to draw a genetic phylogenetic tree.The results showed that the nucleotide sequences of Penton protein of 12 serotypes had more than 99.2% homology with their respective standard strain,among which the homology of FAdV-1,FAdV-2,FAdV-3,FAdV-4,FAdV-6,FAdV-7,FAdV-8a,FAdV-8b,FAdV-10 and FAdV-11 were as high as 100%.This further confirmed the consistency between the laboratory preserved strains and the world standard strains.However,although Penton protein was highly conserved,there were still significant differences among different species.The nucleotide homology between FAdV-A1 and other species was 70.6%-73.3%,while that of FAdV-B5 was 70.6%-77.9%.The nucleotide homology between FAdV-C strains of different serotypes was 99.6%,while homology between FAdV-C4 and other species was 71.2%-73.4%.The nucleotide homology between FAdV-D strains of different serotypes was 95.6%-98.7%,while the highest homology between FAdV-D and other species was 85.3%.The nucleotide homology between FAdV-E strains of different serotypes was 98.2%-99.4%,while the highest homology between FAdV-E and other species was 85.3%.In conclusion,the homology difference between strains of the same species was small,and that of different species was significant.FAdV could be divided into A,B,C,D and E species according to nucleotide sequence of Penton protein.This study successfully cloned 12 serotypes Penton gene of FAdV and performed genetic evolution analysis,which laid the foundation for the diagnosis,monitoring and identification of FAdV in the future.     

Outbreaks of hydropericardium syndrome and molecular characterization of Korean fowl adenoviral isolates

Outbreaks ofhydropericardium syndrome (HPS), caused by fowl adenovirus serotype 4 (FAdV-4), have occurred in Korea and caused severe economic loss due to mortality and weight loss. From these outbreaks, several adenoviruses were isolated and identified in samples from broilers, layers, breeders, and native Korean fowl. In pathologic examinations, hydropericardium and multifocal hepatic necrosis, with an intranuclear inclusion body in hepatocytes, were observed. Specific adenovirus particles were also observed in the nucleus of hepatocytes, by electron microscopic examination. Polymerase chain reaction (PCR) analysis of the hexon gene identified all of the isolates as FAdV, serotype 4 and genotype C. To reproduce FAdV-4 field cases, 8- and 52-week-old specific pathogen free (SPF) chicks were infected intramuscularly with the field isolate CBU070244. The mortality rate of infected chicks ranged from 10%-40%, and specific pathologic lesions, such as swollen livers and hydropericardium, were observed. Further studies to determine the prevalence of infection, and analysis of the economic impact to the poultry industry, are needed in the near future.     

鸡腺病毒12个血清型代表毒株Penton蛋白基因分析

为了解鸡腺病毒（fowl adenovirus,FAdV）Penton基因的遗传进化规律,试验根据GenBank中已公布的各基因型序列设计特异性引物,通过PCR技术分别扩增12个血清型毒株的Penton基因,连接至pEASY-Blunt Simple Cloning Vector上进行序列测定,并将12个血清型毒株Penton蛋白的核苷酸序列与NCBI上已公布的标准毒株的核苷酸序列使用ClustalW法进行分析比对,绘制遗传进化树。结果显示,12种血清型Penton蛋白核苷酸序列与各血清型标准毒株同源性均在99.2%以上,其中FAdV-1、FAdV-2、FAdV-3、FAdV-4、FAdV-6、FAdV-7、FAdV-8a、FAdV-8b、FAdV-10、FAdV-11与对应标准株同源性高达100%,这进一步证实了实验室保存毒株与世界相应标准毒株的一致性。Penton蛋白虽然保守性较高,但不同种之间仍存在明显差异。FAdV-A1与其他种毒株同源性为70.6%~73.3%;FAdV-B5与其他种毒株同源性为70.6%~77.9%;FAdV-C同种不同血清型之间核苷酸同源性为99.6%,FAdV-C4与其他种之间同源性71.2%~73.4%;FAdV-D同种不同血清型之间核苷酸同源性为95.6%~98.7%,与其他种之间最高为85.3%;FAdV-E同种不同血清型之间核苷酸同源性为98.2%~99.4%,不同种间最高为85.3%。即相同种毒株之间差异较小,不同种毒株之间差异较大。依据Penton蛋白的核苷酸序列同样可以将FAdV分为A、B、C、D、E 5个种。本研究通过成功克隆FAdV 12种血清型Penton基因,并进行遗传进化分析,为今后对FAdV诊断、监测及毒株鉴定提供了参考。     

荧光定量RT-PCR检测禽白血病病毒方法的建立及应用

gag基因是禽白血病病毒(ALV)的群特异性基因,根据GenBank中登录的gag基因的保守序列(E46390),设计合成了1对引物,建立了基于SYBR GreenI模式的检测禽白血病病毒的实时荧光定量RT-PCR方法。该方法只对目的基因有扩增,对其它无关病毒核酸无特异性扩增;扩增效率为94.6%;在8.2×102～8.2×107拷贝的范围内有很好的线性关系(Y=3.46X+31.8,r=0.9995);最低可检测82个拷贝的病毒核酸,与普通PCR方法相比,灵敏度高出1000倍。组内CV为0.28%～1.45%;组间CV为2.13%～3.84%;对151例临床疑似样本的检出率为54.9%(83/151)。随机选择15份阳性样本PCR产物克隆测序,结果证明扩增片断为ALV的特异序列,与ALVgag基因核苷酸同源性为97.8～98.9%;对重庆14个县的14个健康商品蛋鸡群的134份粪便棉拭子进行检测,ALV的检出率为38.1%,鸡群的阳性率为14/14。同时用实时RT-PCR方法和ELISA方法对从种鸡场随机采集的30份100日龄蛋鸡的血清进行检测,实时RT-PCR检测率为5/30,ELISA方法检测率为4/30。本方法的建立为禽白血病的快速诊断、大规模检疫、监测、流行病学调查以及药物筛选等提供了新的检测方法。     

鸡鸭鹅A型禽腺病毒的PCR检测和分析

为了解A型禽腺病毒在家禽中的分布情况,从不同地区外表健康家禽中采集泄殖腔拭子,根据鸡胚致死孤儿病毒（Chicken Embryo Lethal Orphan Virus,CELOV）的全基因组序列设计引物,采用PCR方法扩增了禽腺病毒（Fovl Adenoviruses,FAV）病毒基因组右未端ITR片段和ORF 8片段。结果表明：A型禽腺病毒在家禽中分布比较广泛,鸡群、鸭群和鹅群的阳性率分别为23．8％、51．7％和17．2％。ITR片段扩增产物测序结果表明,禽腺病毒分离株与A型禽腺病毒CELOV、FAV-JS株在ITR片段具有很高同源性,而与FAV-9、火鸡腺病毒A型和鸭腺病毒A型的同源性较低。ORF8片段扩增产物测序结果表明,分离株的ORF8的序列与CELOV、FAV-JS株的ORF8片段也具有高度同源性。     

Molecular detection and characterization of fowl adenovirus associated with inclusion body hepatitis from broiler chickens in Egypt

Tropical Animal Health and Production - A case-control study was performed to assess prescence of inclusion body hepatitis (IBH) caused by fowl adenoviruses (FAdVs) at Kafr EL-Shiekh Governorate,...     

Characterization of fowl adenoviruses isolated in Ontario and Quebec, Canada

Fowl adenoviruses (FAdV) are generally considered ubiquitous, but certain serotypes and strains are known to be associated with primary diseases, such as inclusion body hepatitis (IBH). Fifty-two FAdV isolates were collected from the provinces of Ontario and Quebec over a 4-year period. These 2 provinces have the largest poultry industries in Canada. Except for one virus, which originated from a guinea fowl, all other viruses were isolated from chicken samples. Most of these were from broilers, although some were from broiler breeders, and one was from layer pullets. Thirty-four isolates were from clinical IBH cases with the final laboratory diagnosis of IBH; however, for 18 isolates, the varied case diagnosis was seemingly unrelated to FAdV. All IBH-associated viruses had deoxyribonucleic acid (DNA) profiles compatible with FAdV species E (28 cases) or species D (6 cases), and the DNA fragment profiles of 26 species E viruses were indicative of serotype 8. Two viruses were serotype 6, as confirmed by virus neutralization. All species D viruses had a DNA profile similar to that of FAdV-2. The number of serotype 8 virus isolations has increased over the years, and by 2001 serotype 8 had become the dominant serotype in Ontario, and continues to be so. Moreover, this virus (FAdV-8) has shown a strong association with IBH.     

鸽疱疹病毒与腺病毒感染的PCR检测方法的建立

鸽疱疹病毒和腺病毒是幼鸽常见的病原体,这些病毒共同引起一种疾病,称为幼鸽疾病综合征。论文建立了鸽疱疹病毒和腺病毒的PCR检测方法和双重PCR检测方法,并对发病鸽子进行了诊断。