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Objective: To investigate the potential correlation between piwi-like RNA-mediated gene silencing 1 (PIWIL1) polymorphisms and susceptibility to epithelial ovarian cancer (EOC). Methods: A case–control study was conducted to evaluate the susceptibility of EOC using multinomial logistic regression analysis. The study analyzed the relationship between five functional single nucleotide polymorphisms (SNPs) in the PIWIL1 gene and EOC risk. Genotyping of 288 cases and 361 healthy samples from South China was identified using a TaqMan assay. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to estimate the relationship between the five selected SNPs and EOC susceptibility. Results: Among the five SNPs analyzed, the rs10848087 G > A and rs7957349 G > C variants significantly increased the susceptibility of EOC, rs10773771 C > T was associated with a decreased risk of EOC, while the rs35997018 and rs1106042 variants were not in Hardy–Weinberg equilibrium (p < 0.05). The rs10848087 G > A was significantly associated with increased risk of EOC in individuals with metastasis, FIGO stage I and III, low and high pathological grade, tumor numbers ≤ 3 and > 3, tumor size > 3 cm and ≤ 3 cm, pregnant more than 3 times, pre-menopausal status, and strong positive expression of ER (estrogen receptor), PR (progesterone receptor), PAX8 (paired-box 8), wild-type p53 (tumor protein 53), WT1 (Wilm's tumor gene), P16 (cyclin-dependent kinase inhibitor 2A). In addition, rs10848087 G > A enhanced the EOC risk of cases with negative/mild positive expression of wild p53 and Ki67, and with or without mutant p53 expression. The rs7957349 G > C variant was linked to an increased risk of EOC in subgroups with certain characteristics, including age equal or less than 53 years, metastasis, clinical stage I, low pathological grade, tumor number, tumor size, pregnant times, post-menopause, pre-menopause, and strong positive expression of wild p53 and Ki67 (Antigen identified by monoclonal antibody Ki-67), as well as without mutant p53 expression. The rs10773771 CT/TT alleles were identified to have a protective effect on EOC in women aged 53 years or older, as well as in cases with metastasis, advanced clinical stage, high pathological grade, multiple tumors, tumor size equal to or less than 3 cm, history of pregnancy, post-menopausal status, and strong positive expression of ER, PR, wild-type p53, PAX8, WT1, P16, and Ki67. Furthermore, rs10773771 CT/TT also showed a protective effect in patients with negative or mildly positive expression of PR, PAX8, wild-type p53, WT1, and P16, as well as positive expression of mutant p53. Compared to the reference haplotype GCG, individuals harboring haplotypes GTG were found to have a significantly decreased susceptibility to EOC. PIWIL1 was significantly expressed in the thyroid, pituitary, and adrenal glands with rs7957349 CC alleles. Conclusions: PIWIL1 rs10848087 and rs7957349 were associated with increased risk of EOC, while rs10773771 may have a protective effect against EOC. These genetic variants may serve as potential biomarkers for EOC susceptibility in the South China population. [ABSTRACT FROM AUTHOR]

Avian hepatitis E virus (HEV) is highly variable and has multiple genotypes. Previous studies showed that the current epidemic strain in China is genotype 5, but the relevant detection was only carried out in flocks with hepatic rupture haemorrhage syndrome, which does not mean that other genotypes do not exist. In this study, a broader analysis involving different chicken flocks was performed to understand the epidemic status of avian HEV in China. The results showed that the HEV‐positive rate of all samples was 7.92% (78/985), and four different genotypes have been identified by analysing a truncate capsid gene fragment, while the homology between them is about 80%. Two of them are separately known as genotype 3 and genotype 5, while the other two are completely unidentified, indicating that there are multiple genotypes of avian HEV prevalent in China. At the same time, the distribution of these genotypes has no obvious geographical clustering pattern, only slightly different in commercial layers, broilers and some indigenous species. This study shows the genetic diversity of avian HEV in China and reminds us to pay more attention to its variation and evolution. [ABSTRACT FROM AUTHOR]

Avian leukosis virus (ALV) is the cause of a variety of tumour diseases in poultry, causing huge economic losses all over the world. As a retrovirus, its genome is highly variable and easily recombined between different subgroups. Previous studies found several recombinant events among subgroup A, B and E, but few data show that in subgroup J, which is the most prevalent and pathogenic in chickens. This study identified and sequenced an emerging recombinant ALV from yellow chicken, and analysis showed that the homology between the env gene of the new isolate and the representative strain (BR119) of subgroup J is as high as 98.7%, while its long terminal repeat (LTR) was highly consistent with some representative strains of subgroup E (94.9%–98.4%). This study also found that such LTR has appeared in some published strains of subgroup B and subgroup K, indicating that it can combine with the coding region of many different subgroups of ALV, thus forming natural recombinant strains. At the same time, a pair of polymerase chain reaction primers were selected according to the sequence, which can specifically detect the recombinant strains in wild, facilitating the future ALV eradication program. Overall, this study reminds us to pay more attention to tracking the genome variation of ALV in the future. [ABSTRACT FROM AUTHOR]

Since early 2018, avian leukosis virus (ALV) has re‐emerged throughout six provinces in Northeast and East of China and caused huge economic losses. In different farms, there are significant differences in clinical symptoms, including morbidity, mortality and location of tumours, on affected animals, which implies that the present strains may have different origins and molecular characteristics. In this study, a systematic epidemiological investigation was conducted in 21 farms in six provinces. Results showed that the virus strains present in this outbreak are highly consistent but carry different mutations. All the strains shared 97.0%–99.0% identity with each other and were highly similar to the GD14J2 strain isolated previously, while different insertion fragments can be found in the env gene of different strains, suggesting that the strains of ALV in this outbreak may have the same ancestors but have gone through different evolutionary trajectories. This study demonstrated that these viruses may point to multiple sources of infection, and all should be identified and taken seriously in the formulation of control plans. [ABSTRACT FROM AUTHOR]

GX0101 is the first field Marek's disease virus (MDV) recombinant with an REV LTR insert isolated in China. We speculated that there was a selective advantage of GX0101 becoming the more prevalent field strain from a very low percentage of recombinant virus. In the study, dual fluorescence quantitative real-time PCR (DF-qPCR) that detects GX0101 and GX0101Δ LTR simultaneously was established based on the genomic difference of GX0101 and its LTR deletion strain GX0101Δ LTR. MDV natural transmission was simulated in specific-pathogen-free (SPF) chicks, and continuous tracking of GX0101 and GX0101Δ LTR in chicks was carried out. The results showed that GX0101 possessed high horizontal transmission capacity, which could infect SPF chicks by contact in a short time and became the predominant strain following contact infections in chicken flocks. GX0101 still had a more significant advantage of horizontal transmission than GX0101Δ LTR after continuous passage even if the initially infectious dose was significantly lower. There were 72 differentially expressed MDV genes between GX0101 and GX0101Δ LTR , with the genes and gene products mainly involved in virus replication, tegument protein, glycoprotein, nucleocapsid protein, immune evasion, tumor development and/or pathogenesis, and hypothetical protein. Sixteen genes related to virus replication and transmission were significantly up-regulated. This is the first study to illuminate that increased horizontal transmission of recombinant MDV due to REV LTR was the competitive advantage of the virus being a prevalent strain and define the differential transcription profile of viral genes between GX0101 and GX0101Δ LTR. This will be helpful for in-depth study on the molecular mechanism of increased horizontal transmission of MDV by REV LTR. [ABSTRACT FROM AUTHOR]

Since 2016, hepatic rupture haemorrhage syndrome (HRHS) appeared in chickens of China and caused huge economic loss. To assess the infection status of the avian hepatitis E virus (HEV) and co‐infected viruses, including avian leukosis virus (ALV), reticuloendotheliosis virus (REV), fowl adenovirus (FAdV), and chicken infectious anaemia virus (CIAV), in farms with HRHS, 180 liver samples were collected from 24 farms in different provinces and detected by strict molecular virology methods. Results showed that the positive rates of HEV, ALV, REV, FAdV, and CIAV were 74.44%, 20.00%, 27.78%, 31.11%, and 12.22%, respectively, whereas there are also 112 samples with co‐infection, for a rate of 58%. Meanwhile, the positive rate of HEV decreased gradually with age; the lowest positive rate of ALV (5.76%) and REV (19.23%) appeared in 25–35 weeks age, during which the positive rate of CIAV was the highest (19.23%); the positive rate of HEV in layers (64.00%) was lower than that of broilers (83.33%), but the positive rates of ALV (38.46%) and CIAV (15.38%) in layers were higher than that of broilers (5.88%, 9.80%); the positive rates of HEV (75.88%) and CIAV (15.60%) in parental generation (PG) were higher than that of commodity generation (CG, 64.10%, 0.00%), whereas the positive rate of ALV showed inverse relationship (PG: 14.89%; CG: 38.46%). Additionally, phylogenetic analysis showed that all the avian HEV identified this study belong to a novel genotype, and found the close relationship between the wild strains (REV and CIAV) and corresponding isolates from contaminated vaccine. The data presented in this report will enhance the current understanding of the epidemiology characteristics in farms with HRHS in China. [ABSTRACT FROM AUTHOR]

The antibody to chicken infectious anemia virus (CIAV) was positive in a specific pathogen-free (SPF) chicken population by ELISA test in our previous inspection, indicating a possible infection with CIAV. In this study, blood samples collected from the SPF chickens were used to isolate CIAV by inoculating into MSB1 cells and PCR amplification. A CIAV strain (SD1403) was isolated and successfully identified. Three overlapping genomic fragments were obtained by PCR amplification and sequencing. The full genome sequence of the SD1403 strain was obtained by aligning the sequences. The genome of the SD1403 strain was 2293 bp with a nucleotide identity of 94.8% to 98.5% when compared with 30 referred CIAV strains. The viral proteins VP2 and VP3 were highly conserved, but VP1 was not relatively conserved. Both amino acids 139 and 144 of VP1 were glutamine, which was in accord with the low pathogenic characteristics. In this study, we first reported that CIAV exists in Chinese SPF chicken populations and may be an important reason why attenuated vaccine can be contaminated with CIAV. [ABSTRACT FROM AUTHOR]

Epidemiological studies of subgroup J avian leukosis virus (ALV-J) and reticuloendotheliosis virus (REV) infections were conducted during 1999 to 2009 on 29 chicken flocks of various commercial and local breeds located in six provinces in China. Samples were typically from chickens with myelocytomas or proventricular lesions. ALV-J was isolated from 25 flocks including seven out of seven flocks containing “yellow chickens” or other local breeds and several flocks of layer chickens. REV was isolated from 19 flocks. Co-infection of ALV-J and REV was confirmed in 11/38 birds of 8/15 flocks with myelocytomatosis and in 11/24 birds of 3/5 flocks with proventricular lesions. Both ALV-J and REV were vertically transmitted in four breeder flocks of local chicken breeds. One experiment in specific pathogen free chickens indicated that co-infection at hatch strongly depressed antibody responses to ALV-J but not to REV. The results suggest that infections with both ALV-J and REV have become endemic in local breeds, including breeder flocks where both viruses appear to be perpetuated by vertical transmission. In addition, both viruses were present in at least some commercial broiler, layer and breeder flocks. Eradication programmes are needed but will be difficult, especially in local breeds. This unprecedented concurrence of simultaneous endemic infections with ALV-J and REV may have serious economic consequences and needs to be better understood. [ABSTRACT FROM AUTHOR]

The present study was conducted to understand epidemiological factors that depress the protective efficacy of vaccination against highly pathogenic avian influenza (HPAI). Specific pathogen free chickens were infected at different ages with immunosuppressive reticuloendotheliosis virus (REV), then vaccinated with inactivated vaccine H5N2 and challenged with HPAI H5N1. Compared with control birds, early REV infection significantly inhibited antibody response to H5N2 vaccine and dramatically decreased protective efficacy. Immunosuppressive effects lasted for 4 months, and high mortality occurred in chickens receiving three vaccinations during 3 months prior to challenge with HPAI H5N1. Epidemiological studies indicated that REV infection and vertical transmission is common in chickens in some areas of southern China. We conclude that vaccination programmes against HPAI will not be fully effective if other immunosuppressive viral infections, such as REV, exist in chicken flocks. [ABSTRACT FROM AUTHOR]

Epidemiological, pathological and molecular studies indicate that subgroup J avian leukosis virus (ALV-J) infections are widely spread in "yellow chickens" of local breeds in China. ALV-J induced tumour mortality and the serological conversion rates to ALV-J were very high in some breeder flocks. Typical myelocytomatosis was demonstrated not only in livers, spleens, kidneys, and sternums, as in white meat-type chickens, but also in thymuses and the bursa of Fabricius. Especially, severe myeloid cell infiltration was found throughout the whole enlarged thymuses of some birds. ALV-J was isolated at high positive rates from both liver tumour samples and embryos collected from breeder flocks with tumours. At the same time, reticuloendotheliosis virus was also co-isolated with ALV-J in some tumour samples and embryos. Sequence analysis of env genes demonstrated that the gp85 and gp37 among six ALV-J isolates from "yellow chickens" of Chinese local breeds varied as highly as among ALV-J strains isolated from white meat-type chickens worldwide. But strain GD0512 isolated in 2005 from a "yellow chicken" farm in southern China had high identity of 95.1% for gp85 or 99.5% for gp37 to strain HN0001 isolated in 2000 from a white meat-type breeder farm in northern China, a much higher identity than to other yellow chicken and white chicken strains. This is the first report of the isolation and identification of ALV-J from yellow chickens of Chinese local breeds and also the first report of vertical co-infection of ALV-J and reticuloendotheliosis virus. The significance of co-infection of ALV-J and reticuloendotheliosis virus in pathogenesis is discussed. [ABSTRACT FROM AUTHOR]

Avian leukosis virus subgroup J (ALV-J) has successively infected white feather chickens, layer hens, cultivated yellow chickens, and indigenous chickens; infection rates and tumorigenicity have attracted increasingly extensive attention in China. To clarify the correlation of the epidemiological phenomenon of ALV-J with the evolution of envelope protein gp85, 140 strains of ALV-J isolated from chickens with different genetic backgrounds from 1999 to 2013 were compared. The homology of the gp85 protein and genetic genealogical relationships between 140 strains of ALV-J and the prototype strain HPRS-103, as well as between the same ALV-J strains and 8 American isolates, were analyzed and compared. The results showed that there was no significant difference in the variation range of homology of the gp85 protein between the prototype HPRS-103 and ALV-J isolates from different genetic backgrounds and different years. However, genetic pedigree analysis showed that virus strains that isolated from the same type of chickens remained close to each other on the phylogenetic tree, which means that there was a correlation between the genetic background of infected chickens and virus strains. Further analysis of amino acid sequences also found similar results and revealed that unique amino acid sites were formed in chickens with different genetic backgrounds, which proved that ALV-J could adapt to the new host through amino acid variation. Genetic sequence phylogenetic tree analysis was more representative than sequence homology comparisons for assessing ALV-J correlations. These conclusions contributed to the control and prevention of ALV infection. ALV-J is still prevalent in Chinese indigenous chickens, more attentions should be given to fulfill the purification. [ABSTRACT FROM AUTHOR]

Avian hepatitis E virus (HEV) is the major causative pathogen of the big liver and spleen disease, hepatitis-splenomegaly syndrome, and hepatic rupture hemorrhage syndrome. Until now, there are 6 different avian HEV genotypes that infect chickens have been reported worldwide. Epidemiologic investigations of the avian HEV demonstrated that avian HEV has been widely spread in China in recent years. In this study, an avian HEV named YT-aHEV was obtained from white-feathered broilers using LMH cells by virus isolation assay in Shandong province, China. The complete genome consists of 6656-nt excluding the poly(A) tail. The isolate was highly similar to the CaHEV strain and segregated into the same branch belonging to avian HEV genotype 3. Indirect immunofluorescence using capsid protein-specific polyclonal antibodies confirmed that YT-aHEV could establish productive infection and replicate stably in LMH cells. Furthermore, an in vivo avian HEV infection model was established successfully in specific pathogen-free chicken embryos by intravenous experiments. In the present study, we demonstrate an avian HEV infection associated with liver lesions of hemorrhage and swelling by LMH cells for the first time in a white-feather broiler flock in China. This research also provides a new diagnosis method for detection of avian HEV, which laid a foundation for the understanding of pathogenicity and molecular biology of this virus for further study. [ABSTRACT FROM AUTHOR]

• A set of methods to sequence the avian HEV was established. • The novel avian HEV shared 79.5–86.9% identities with others. • The new isolate contains various mutations in its functional genes. Since 2016, severe outbreaks of hepatic rupture hemorrhage syndrome (HRHS) associated with infections of tentative novel avian hepatitis E virus (HEV) have emerged in chickens in China, causing increased mortality and decreased laying rate in adult hens and disturbing the hatching and breeding of chicks. To further identify the genotype and gain a better understanding of the genetic properties of the avian HEV responsible for that, a strain from Hebei province was isolated, purified and sequenced in this study. Results identified a novel avian HEV genotype, sharing 79.5–86.9% identities with other published avian HEV strains, and having higher identities with Orthohepevirus A HEV strains. More importantly, the new isolate contains various amino-acid substitutions in its functional proteins, including methyltransferase, helicase, RNA-dependent RNA polymerase. The data presented in this report will enhance the current understanding of the genetic diversity of the avian HEV and provide additional insight into the critical factors that determine the pathogenicity. [ABSTRACT FROM AUTHOR]

Chicken infectious anemia (CIA) is caused by chicken anemia virus (CAV). Recently, severe anemia has emerged in layer chickens (8 to 10-week-old) on poultry farms in China. However, the etiological characteristics and pathogenic potential of CAV in chickens at 6 weeks or older are not well understood. In this study, we isolated a CAV strain, termed SD15, from two-month-old chicken with severe anemia and analyzed the genetic evolution relationship. We found that strain SD15 had the highest homology (98.9%) with CAV18 strain. Comparison with 33 reference strains revealed 16 amino acid mutations in strain SD15, two of which were previously unknown (F210S in VP1 and L25S in Vp3). Compared with low pathogenic strains (Cux-1 and C14), highly pathogenic strains (SDLY08 and SD15) had three base mutations in their noncoding region. To further understand its pathogenicity, 10-week-old specific-pathogen-free (SPF) chickens were challenged with the novel strain and SDLY08. No obvious clinical symptoms were observed in the SDLY08 group. However, SD15-infected chickens showed significant growth retardation and immunosuppression. The main manifestations of immunosuppression were the significantly reduced thymus and bursa indices and AIV-H9 vaccine-induced antibody levels (P < 0.05). The lowest number of red blood cells in the SD15 group was just 60% of that in the control group. Taken together, the novel strain SD15 not only showed higher pathogenicity but also exhibited the potential ability to break the age resistance of older chickens to CAV. Our study enhanced the understanding of the epidemiological characteristics of chickens infected with severe anemia and can facilitate the development of improved control strategies of CIA in China., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Fang, Jia, Hu, Wang, Cui, Qi and Zhao.)

Since June 2013, hydropericardium-hepatitis syndrome caused by putative novel fowl adenovirus 4 (FAdV-4) infection has spread all over China, leading to great economic losses. Previous study found that the use of attenuated vaccines contaminated with FAdV-4 is likely to be an important cause of such large-scale transmission. Here, we sequenced the whole genome of this strain through the next-generation sequencing and carried out a retrospective analysis of the FAdV-4 strains that have been determined in China recently. Results show the vaccine strain was almost 100% identical with wild virus strains, especially with 4 strains considering the difference of the GA repeat region, further linking the relationship between vaccine contamination and FAdV-4 prevalence in China. Meanwhile, there is no time and regional preference for the emergence of FAdV-4 strains with different molecular characteristics in China, which indicates that there may be multiple routes of transmission of this virus, suggesting that we still need to pay more attention to and formulate correct prevention and control in the future., (Copyright © 2020. Published by Elsevier Inc.)

Newcastle disease virus (NDV)-attenuated vaccine has been widely used to prevent ND in poultry flocks, while many reports also mentioned the exogenous virus contamination in attenuated vaccines, which might be the reason for the widespread of some contagious diseases. Recently, the chicken infectious anemia virus (CIAV) contamination in the NDV-attenuated vaccine was also found in China, though no systemic study has studied the pathogenicity or infection mechanism of this special transmission route. Accordingly, simulation experiments were launched using CIAV isolated from a contaminated NDV-attenuated vaccine. Results showed that using NDV-attenuated vaccine contaminated with CIAV could cause CIA in chickens with obvious symptoms, including anemia, hemorrhage, lymphoatrophy, and growth retardation, while the synergistic reaction of CIAV and LaSota prompted their multiplication in vivo and disturbed the production of antibodies against each other. And CIAV could significantly reduce the NDV antibody titers and decrease the protective effectiveness. This study showed the synergetic pathogenicity of CIAV and LaSota strain after using contaminated NDV-attenuated vaccine, helping us to understand how the CIAV causes infection and induces severe diseases with a relatively low dose through the mouth, as well as reminding us that the damage of an attenuated vaccine contaminated with CIAV even in extremely low dose is not insignificant., (© 2018 Poultry Science Association Inc.)

In recent years, there has been an increase in reported cases of fowl adenovirus serotype 4 (FAdV-4) in chickens in China. The use of live attenuated vaccines contaminated with FAdV-4 has been proved to be one of the important causes of massive outbreaks of hydropericardium syndrome. To detect the contamination with FAdV-4 in attenuated vaccines more promptly and accurately, a droplet digital PCR (ddPCR) assay was developed for the rapid detection of FAdV-4 and FAdV-10. The ability of this assay to detect FAdV-4 contamination in attenuated Newcastle disease virus vaccines was assessed in comparison to a quantitative real-time PCR (qPCR) and a conventional PCR assay. The findings indicated that the ddPCR assay could detect FAdV-4 contamination at 0.1 EID 50 /1,000 feathers, while the qPCR could detect FAdV-4 contamination at 1 EID 50 /1,000 feathers with identical genomic targets, which was 1,000-fold more sensitive than conventional PCR detection with a sensitivity of 10 2 EID 50 /1,000 feathers. The ddPCR assay also showed high specificity for FAdV-4/10 and no positive signals were detected for other FAdVs. Consequently, the intuitive and rapid results were especially suitable for the detection of FAdV-4 contamination in vaccines. In this study, a ddPCR assay was developed to effectively detect and quantify low-dose FAdV-4 contamination, providing a new method for rapid detection of FAdV-4 contamination in various samples, especially vaccines., (Copyright © 2018. Published by Elsevier B.V.)

Since 2016, hepatic rupture haemorrhage syndrome (HRHS) has emerged in layer and broiler breeder hens in several provinces of China, and novel genotype avian hepatitis E viruses were detected from these chickens. To gain a better understanding of the genetic properties of the novel avian HEV strain, the capsid gene of four isolates from birds at four farms experiencing HRHS in different geographical regions were determined and compared with those of reported pathogenic and nonpathogenic avian HEV isolates as well as mammalian HEVs. Results showed that all those isolates share 80.1%-88.2% nucleotide sequence identity and 89.3%-91.9% amino acid sequence identity with other published avian HEV strains, while phylogenetic analysis further demonstrate that a novel genotype avian HEV was epidemic in China. Meanwhile, sequence analysis revealed that those novel isolates contain various amino acid mutations and even a hypervariable region in their major antigenic domains, which might be the critical factors for the pathogenicity elevation and even change their antigenicity. The data presented in this report will enhance the current understanding of the epidemiology and genetic diversity of the novel genotype avian HEV in China and provide additional insight into the critical factors that determine the pathogenicity of it., (© 2018 Blackwell Verlag GmbH.)

The diagnosis of avian leukosis virus subgroup J (ALV-J) infection in Chinese Partridge Shank chickens was confirmed by necropsy, histopathological examinations, antibody tests, viral isolation, immunofluorescence assays, and sequence analysis. Myelocytoma, myeloma, and fibrosarcoma were simultaneously found in Partridge Shank flock with ALV-J infection. Sequence analysis of the env genes of ALV-J demonstrated that both gp85 and gp37 were highly homologous among the three strains from local chickens of those among ALV-J strains isolated from white meat-type chickens. The phylogenetic trees indicated that the three strains isolated in this study were closely related to reference strains isolated in so-called Chinese yellow chickens and some strains isolated from white meat-type chickens, both from the USA and China. The observed ALV-J infection was the first report on Partridge Shank chickens, and myelocytoma, myeloma, and fibrosarcoma were found at the same time in this batch of local chickens., (© 2015 Poultry Science Association Inc.)

The strain JS11C1, a member of a putative new subgroup of avian leukosis virus (ALV) that is different from all six known subgroups from chickens based on Gp85 amino acid sequence comparison, was isolated from Chinese native chicken breeds in 2012. In order to further study the genome structure, biological characteristics, and the evolutionary relationship of the virus with others of known subgroups from infected chickens, we determined the complete genome sequence, constructed an infectious clone of ALV strain JS11C1, and performed comparative analysis using the whole genome sequence or elements with that of other ALVs available in GenBank. The results showed that the full-length sequence of the JS11C1 DNA provirus genome was 7707 bp, which is consistent with a genetic organization typical of a replication-competent type C retrovirus lacking viral oncogenes. The rescued infectious clone of JS11C1 showed similar growth rate and biological characteristics to its original virus. All the comparison analyses based on whole genomes support the opinion that the new isolates are relatively distantly related to any known subgroups of ALVs and might be classified as a new subgroup., (© 2014 The Authors.)

To identify if any exogenous avian leukosis virus (ALV) exists in a live vaccine of poultry according to the directives of the Ministry of Agriculture of the People's Republic of China, a live vaccine strain of the Newcastle disease virus (NDV) was neutralized using an anti-NDV antibody, and was subsequently used to inoculate DF-1 cells to investigate the presence of exogenous ALV. The DF-1 cells were cultured for 21 d and subsequently screened using an ELISA for the p27 antigen of the ALV. An exogenous ALV, designated ALV-NDVP4, was identified. The nucleotide sequence of the gp85 gene of the ALV-NDVP4 was compared with those of the various subgroups of the ALV. The amino acid sequence identities for the predicted gp85 of the ALV-NDVP4 and those of the ALV reference strains ranged from 88.2 to 99.5% for the 12 of the subgroup A strains of ALV (ALV-A) and from 82.7 to 87.4% for the B, C, D, and E subgroup strains. The amino acid sequence identities for the gp85 of the ALV-NDVP4 and those of the subgroup J reference strains ranged from 48.7 to 49.9%. The ALV-NDVP4 shared the highest level of homology with the SDAU09C3 strain of ALV-A, which was isolated in China, suggesting a common origin. This is the first report of ALV-A contamination in a live vaccine for poultry in China. Our findings highlight the need for improved monitoring methods for poultry vaccine production., (© 2014 Poultry Science Association Inc.)

Background: Marek's disease virus (MDV) causes an acute lymphoproliferative disease in chickens, resulting in immunosuppression, which is considered to be an integral aspect of the pathogenesis of Marek's disease (MD). A recent study showed that deletion of the Meq gene resulted in loss of transformation of T-cells in chickens and a Meq-null virus, rMd5ΔMeq, could provide protection superior to CVI988/Rispens., Results: In the present study, to investigate whether the Meq-null virus could be a safe vaccine candidate, we constructed a Meq deletion strain, GX0101ΔMeq, by deleting both copies of the Meq gene from a pathogenic MDV, GX0101 strain, which was isolated in China. Pathogenesis experiments showed that the GX0101ΔMeq virus was fully attenuated in specific pathogen-free chickens because none of the infected chickens developed Marek's disease-associated lymphomas. The study also evaluated the effects of GX0101ΔMeq on the immune system in chickens after infection with GX0101ΔMeq virus. Immune system variables, including relative lymphoid organ weight, blood lymphocytes and antibody production following vaccination against AIV and NDV were used to assess the immune status of chickens. Experimental infection with GX0101ΔMeq showed that deletion of the Meq gene significantly decreased immunosuppression in chickens caused by pathogenic MDV., Conclusion: These findings suggested that the Meq gene played an important role not only in tumor formation but also in inducing immunosuppressive effects in MDV-infected chickens.

In the 3 years leading up to November 2009, 6 different types of naturally occurring neoplasms associated with avian leukosis virus subgroup J (ALV-J) were diagnosed by histopathology, polymerase chain reaction (PCR) and immunohistochemistry (IHC) in 140 layer hens out of approximately 100,000. The most prevalent tumor type was hemangioma (50%) in commercial layer flocks; the second most prevalent neoplasm type was myelocytoma (38.6%); a small number of ALV-J positive lymphomas (4.3%) that were not associated with Marek's disease (MD) or lymphoid leukosis (LL) was observed. Histiocytic sarcomas (2.1%) were found mainly in the spleen, liver and kidney. Fibrosarcomas (2.8%) presented as metastatic thigh, liver, lung and kidney neoplasms. Three cases of intestinal adenocarcinoma (2.1%) were found associated with ALV-J. Chickens with multiple tumors were a common phenomenon. Usually, hemangiomas plus myelocytomas (8.6%), myelocytomas plus histiocytic sarcomas (2.1%), hemangioma plus myelocytoma and lymphoma (3.6%) were found in various viscera organs. The present report describes the occurrence of multiple neoplasms associated with ALV-J in field layer hens.

Objective: To study the epidemiological status of reticuloendotheliosis virus (REV) infection in ducks., Methods: Two hundred and twenty tissue samples of the Bursa, spleens and livers were randomly collected from 97 sick or dead ducks from 3 areas in Shandong Province, China. REV infections were tested by virus isolation in cell cultures, direct dot blot hybridization, regular PCR and nest-PCR with tissue-extracted DNA as the templates. PCR products of env gene fragments were cloned and sequenced, sequences of env gene fragments were compared and analyzed., Results: REV infections were detected in 35/39 (90%) bursal samples, 54/84 (64%) spleens and 32/97 (33%) livers by Nest-PCR. The positive rate of bursal samples was significantly higher than spleen and liver samples (P < 0.01). No positive sample was detected by virus isolation, direct dot blot hybridization or regular PCR from the same Bursa, spleen and liver samples. In sequence comparisons of amplified env gene fragments, Yinan-1 and Binzhou-1 had 99.8% of identity with reference SNV strain isolated from ducks in USA, and Linqu-1 had 100% identity with two other reference strains isolated from chickens in USA. However, they had lower homology with strains isolated from chickens in China., Conclusion: More attention should be given to bursal samples in detection of REV. Since REV was existing only at a very low level in infected samples and difficult to be detected, nest-PCR should be conducted as the more sensitive assay. Sequence homology comparisons and phylogenetic tree analysis suggested that REV infections in these ducks may originally come from imported breeder ducklings without inspection for REV.

A velogenic Newcastle disease virus (NDV) strain, designated as SRZ03, was isolated from an egg layer flock with NDV vaccine immunization failure in China in 2003. Recombination was found in the F gene of SRZ03. Complete genome sequences analysis indicated that the N-terminal of SRZ03 F gene originated from a genotype II NDV strain, whereas the C-terminal of F gene and the rest of the genes originated from a prevalent velogenic genotype VII NDV strain. It provides us valuable information for understanding the recombination of nonsegmented negative-sense RNA viruses.

Two commercial flocks of Chinese partridge experienced increased mortality associated with a wasting disease at 120-day old in June 2006. Postmortem examination of dead chickens consistently showed visceral tissues mainly proventriculus, liver and spleen were diffuse enlargement. Microscopic examination revealed masses of immature lymphocytes with frequent mitotic figures were seen in various tissues including proventriculus, liver, spleen, kidney, heart, lung, thymus and intestine. Reticuloendotheliosis virus (REV) was isolated from each of four blood samples. Viral antigens were observed in cultured CEF (SPF embryos came from the Ji-nan poultry institute) inoculated blood samples via on indirect immunofluorescent assay. Three hundred bp fragments of LTR of REV obtained from liver samples of six chickens by PCR. This disease has not previously been reported in Chinese partridge. Chinese partridge may represent a potential reservoir of infection for other Chinese local chickens.

In this study, a Chinese field strain of subgroup J avian leukosis virus (ALV-J), NX0101, was studied for its immunosuppressive effects in both commercial broilers and SPF white Leghorn chickens infected at 1 day of age. Our data demonstrated that NX0101 induced much more significant body and immune organ weight loss in the infected commercial broiler chickens in an earlier age than that in the SPF white Leghorn chickens. At the same time antibody responses to vaccinations of Newcastle disease virus (NDV) and infectious bursa disease virus (IBDV) in the NX0101-infected chickens were also evaluated and compared between the commercial broiler chickens and the SPF white Leghorn chickens. Compared with the control group of chickens, the hemagglutination inhibition (HI) antibody response to NDV vaccines was significantly reduced in the NX0101-infected commercial broiler chickens from as early as 20 days after vaccination. However, no significant difference in HI antibody response was seen when HI titers reached their peaks in the NX0101-inoculated and control SPF white Leghorn chickens, except it declined significantly faster in infected birds. Neither of these two types of chickens showed significant decrease of antibody response to IBDV vaccination. Herein, we conclude that this NX0101 strain of ALV-J could selectively suppress humoral immune reactions to NDV, especially in broilers. But challenge experiments were not conducted and, therefore, it cannot be known if decreased antibody levels correlated with decreased protection against NDV in this case.

Eight Chinese field strains of subgroup J avian leukosis viruses (ALV-J) were isolated from broilers or parent stocks during January 1999 to April 2001. One strain, SD9902, was an acute transforming virus, able to induce typical myelocytomatosis in 22-38 days after inoculation of 1-day-old meat-type chicks. The envelope protein and 3'-untranslated region (UTR) of the eight field strains were compared with the U.K. prototype HPRS-103 and several U.S. field strains isolated in 1993-97. All Chinese strains shared an almost identical deletion with the U.S. strain 4817 in the E element region of 3'-UTR when compared with the prototype HPRS-103, indicating that they have a very close phylogenic relationship. Every year, China has to import grandparent stocks of meat-type chickens, mainly from the United States. Chinese isolates should represent a part in the phylogenic tree of U.S. ALV-J evolution. Envelope protein gp85 amino acid sequence analysis demonstrated that, interestingly, all recent Chinese isolates were more closely related to HPRS-103 and the earliest U.S. isolates but not to the late U.S. isolates. The result implies that envelope gp85 may not have diverged from prototype and older strains. It is also possible that some recently imported birds could have been infected by the older viruses that were introduced in the late 1990s.