Molecular Characteristics and Pathogenicity of an Avian Leukosis Virus Isolated from Avian Neurofibrosarcoma

Simultaneous Detection of Three Subgroups of Avian Leukosis Virus Using the Nanoparticle-Assisted PCR Assay

Nanoparticle-assisted polymerase chain reaction (nanoPCR) is a novel method for the rapid detection of pathogens. A sensitive and specific multiple nanoPCR assay was developed for simultaneous detection of avian leucosis virus (ALV) subgroups A, B and J. In this study, three pairs of primers were designed, based on the conserved region of the gp85 gene. An exploration of the optimal primer concentration and annealing temperature were carried out, for better performance of the nanoPCR assay. According to the results, the multiple nanoPCR assay amplified 336 pb, 625 bp and 167 bp fragments of ALV-A, -B and -J, respectively, and showed no cross-reactivity with irrelevant pathogens, suggesting the excellent specificity of the assay. The constructed standard DNA templates were used to estimate the limit of detection. As shown by the results, the detection limit of the nanoPCR assay was nearly 10 copies/μL. To further evaluate the detection ability of the assay, 186 clinical samples were detected using the nanoPCR assay, among which, 14 samples were confirmed as ALV positive; the results were further confirmed by sequencing. In conclusion, a highly specific and sensitive nanoPCR assay was successfully developed, which could be a useful tool for clinical diagnosis as well as for the discrimination of ALV-A, -B and -J.

Epigenetic Regulation in Primary CNS Tumors: An Opportunity to Bridge Old and New WHO Classifications

Originally approved in 1979, a specific grading classification for central nervous system (CNS) tumors was devised by the World Health Organization (WHO) in an effort to guide cancer treatment and better understand prognosis. These "blue books" have since undergone several iterations based on tumor location, advancements in histopathology, and most recently, diagnostic molecular pathology in its fifth edition. As new research methods have evolved to elucidate complex molecular mechanisms of tumorigenesis, a need to update and integrate these findings into the WHO grading scheme has become apparent. Epigenetic tools represent an area of burgeoning interest that encompasses all non-Mendelian inherited genetic features affecting gene expression, including but not limited to chromatin remodeling complexes, DNA methylation, and histone regulating enzymes. The SWItch/Sucrose non-fermenting (SWI/SNF) chromatin remodeling complex is the largest mammalian family of chromatin remodeling proteins and is estimated to be altered in 20-25% of all human malignancies; however, the ways in which it contributes to tumorigenesis are not fully understood. We recently discovered that CNS tumors with SWI/SNF mutations have revealed an oncogenic role for endogenous retroviruses (ERVs), remnants of exogenous retroviruses that integrated into the germline and are inherited like Mendelian genes, several of which retain open reading frames for proteins whose expression putatively contributes to tumor formation. Herein, we analyzed the latest WHO classification scheme for all CNS tumors with documented SWI/SNF mutations and/or aberrant ERV expression, and we summarize this information to highlight potential research opportunities that could be integrated into the grading scheme to better delineate diagnostic criteria and therapeutic targets.

Polyostotic osteosarcoma associated with avian leukosis virus infection in a captive bare-faced curassow (Crax fasciolata)

Background

Osteosarcoma is a malignant mesenchymal bone tumor. Although it is a common tumor in the appendicular skeleton of dogs and cats, it is rarely reported in birds. Retroviruses are usually associated with solid tumor development in different avian species.

Case presentation:

This report aims to describe a case of osteosarcoma associated with the avian leukosis virus in a captive bare-faced curassow (Crax fasciolata). A captive adult female bare-faced curassow presented with lameness, hyporexia, and a non-ulcerative and firm tumor in the right femur. The bird was euthanized due to the poor prognosis. Histopathology revealed an infiltrative mesenchymal neoplasm consisting of spindle cells with moderate cell pleomorphism, organized in bundles and interspersed by marked deposition of the osteoid matrix, which was compatible with osteosarcoma affecting both femur and tibiotarsus, with renal metastasis. Immunohistochemistry of the primary and metastatic tumor demonstrated vimentin expression by neoplastic cells. Samples of the neoplasm, bone marrow, and spleen were processed for PCR, which enabled the demonstration of proviral avian leukosis virus (ALV) DNA.

Conclusions

To the best of our knowledge, this is the first report of an osteosarcoma in a bare-faced curassow with an unusual polyostotic manifestation and associated with ALV infection.

Neuropathogenicity of newly isolated avian leukosis viruses from chickens with osteopetrosis and mesenchymal neoplasms

ABSTRACT The prototype fowl glioma-inducing virus (FGVp) causes fowl glioma and cerebellar hypoplasia in chickens. In this study, we investigated whether a strain of avian leukosis virus (ALV), associated with avian osteopetrosis and mesenchymal neoplasms, is able to induce fowl glioma. We encountered avian osteopetrosis and mesenchymal neoplasms, including myxosarcoma and rhabdomyosarcoma, in Japanese native chickens used for both egg-laying and meat production. These birds were also affected by non-suppurative encephalitis and glioma in their brains. Four ALV strains (GifN_001, GifN_002, GifN_004, GifN_005) were isolated, and a phylogenic analysis of envSU showed that these isolates were classified into different clusters from FGVp and the variants previously reported. Whereas the envSU shared a high identity (94.7%) with that of Rous sarcoma virus (strain Schmidt-Ruppin B) (RSV-SRB), the identity between envTM of GifN_001 and that of FGVp was high (94.5%), indicating that GifN_strains may emerge by recombination between FGVp and other exogenous ALVs. Specific-pathogen-free chickens inoculated in ovo with GifN_001 revealed fowl glioma and cerebellar hypoplasia. These results suggest that the newly isolated strains have acquired neuropathogenicity to chickens.

Spontaneous spinal plexiform perineurioma in a juvenile chicken ( Gallus domesticus)

A 2-mo-old pet chicken ( Gallus domesticus) was presented because of lameness and a hind limb mass of 1 mo duration. Radiographs revealed a soft tissue mass extending from the mid-femur into the body wall. Cytology of a sample obtained from a fine-needle aspirate was unremarkable. The bird was prepared for surgical investigation of the mass but died acutely at the time of pre-medication. Autopsy revealed an extradural mesenchymal neoplasm that focally compressed the lumbar spinal cord, extended into and along the adjacent nerve structures, and displaced the kidneys, skeletal muscle, and body wall. Histopathology was consistent with a perineurioma, which was positive for alcian blue and negative for S100, GLUT1, and neurofilament proteins on immunohistochemistry. PCR testing of tumor tissue was negative for gallid herpesvirus 2 (Marek's disease virus) and avian leukosis virus. Although the etiology of the mass was not determined, our case highlights a severe manifestation of an uncommonly diagnosed tumor in the chicken. Though uncommon, perineurioma should be considered a differential diagnosis for lameness in the chicken.

Isolation, identification, and phylogenetic analysis of two avian leukosis virus subgroup J strains associated with hemangioma and myeloid leukosis

Cases of myeloid leukosis and hemangioma associated with avian leukosis virus subgroup J (ALV-J) are becoming more frequent in China in commercial layer chickens and breeders of egg-type chickens. In this study, two strains of ALV-J (SCAU11-H and SCAU11-XG) associated with hemangioma and myelocytoma were isolated from commercial broiler breeder animals in 2011. Their full-length proviral sequences were analyzed, revealing several unique genetic differences between the two isolates, and suggesting that the two viruses were derived from two distinct lineages. Strain SCAU11-H showed high sequence homology to early Chinese isolates associated with hemangioma, while strain SCAU11-XG was genetically closer to the prototype strain, HPRS-103. The complete genomic nucleotide sequences of SCAU11-H and SCAU11-XG were 7471 bp and 7727 bp in length, respectively. They shared 94.8% identity with each other, and had 94.0-96.8% nucleotide identity to ALV-J reference isolates. Homology analysis of the env, pol, and gag genes of the two isolates and other references strains showed that the gag and pol genes of the two viruses were more conserved than the env gene. In addition, the two isolates had significant deletions and substitutions in their 3'-UTR regions, compared to HPRS-103. These results suggest that the env gene and the 3'-UTR regions in these ALV-J isolates have evolved rapidly, and might be involved in the oncogenic spectrum of ALV-J. The results of this study contribute to our further study of the relationship between ALV integration patterns and multi-pathotypes associated with ALV-J.

The passage of cells can improve the detection rate of avian leukosis virus to facilitate the elimination of avian leukosis in chickens

Avian leukosis (AL) is one of the most harmful diseases to the poultry industry in China. The detection of the avian leukosis virus (ALV) p27 antigen plays a decisive role in the elimination of avian leukosis. To explore the influence of passaging cells on the detection rate of the ALV p27 antigen, 21 aseptic anticoagulated blood samples were collected from 21 chickens for which the cloacal swabs were positive for the p27 antigen to inoculate two sets of cell culture plates containing DF1 cells. The cells were cultured for 4 d, one set was passaged, and the other set was not. After the DF1 cells had been cultured for 9 d, the ALV p27 antigen in the supernatants of the two sets was detected by ELISA. The results showed that the p27 antigen-positive rate for the passaged cells was 71.43% (15/21), higher than that of the cells that were directly cultured, which was 42.86%. There was a strong correlation, as high as 0.928, with respect to the S/P value of the p27 antigen in the supernatant between the two sets. In conclusion, there was a strong correlation between the results for the passaged and unpassaged cells, and the passage of cells greatly improved the detection of the p27 antigen.

Epidemiological study of fowl glioma-inducing virus in chickens in Asia and Germany

Fowl glioma-inducing virus (FGV), which belongs to avian leukosis virus (ALV) subgroup A, induces fowl glioma. This disease is characterized by multiple nodular gliomatous growths of astrocytes and has been previously reported in Europe, South Africa, Australia, the United States and Japan. FGV and FGV variants have spread to ornamental Japanese fowl, including Japanese bantams (Gallus gallus domesticus), in Japan. However, it is unclear how and where FGV emerged and whether FGV is related to the past fowl glioma in European countries. In this study, the prevalence of FGV in European, Asian and Japanese native chickens was examined. FGV could not be isolated from any chickens in Germany and Asian countries other than Japan. Eighty (26%) out of 307 chickens reared in Japan were positive by FGV-screening nested polymerase chain reaction and 11 FGV variants with an FGV-specific sequence in their 3' untranslated region were isolated. In addition, four other ALVs lacking the FGV-specific sequence were isolated from Japanese bantams with fowl glioma and/or cerebellar hypoplasia. These isolates were considered to be distinct recombinant viruses between FGV variants and endogenous/exogenous avian retroviruses. These results suggest that the variants as well as distinct recombinant ALVs are prevalent among Japanese native chickens in Japan and that FGV may have emerged by recombination among avian retroviruses in the chickens of this country.