Biology of Avian Retroviruses

An ultrastructural and histological study was performed to determine the degree of differentiation of the neoplastic cells. The histological study revealed neoplastic cells with pleomorphism, oval nuclei, prominent nucleoli, irregularly distributed chromatin, atypical mitotic figures and moderate amount of cytoplasm containing spherical eosinophilic granulations, typical features of the myeloid lineage. Ultrastructurally, there were cells with an electron-dense, oval and voluminous nucleus, with predominant euchromatin and cytoplasm containing many spherical, electron-dense and homogeneous granules, indicative of myelocytes with differentiation to eosinophils. Type-C viral particles were also seen in the intercellular space of renal tubules and inside the intracytoplasmic vesicles of immature myelocytes in the bone marrow and ovary. PCR was positive to ALV-J.Keywords: chicken, avian leukosis, avian oncovirus, histopathology, ultrastructure RESUMO Caracterizaram-se a linhagem e o grau de diferenciação das células neoplásicas no estudo

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“…The shape of the central core and the budding morphology were extremely suggestive of avian leukosis virus (Payne, 1992).…”

Section: Discussionmentioning

confidence: 99%

“…ALV-J has a tropism for chicken bone marrow cells and induces their neoplastic transformation (Payne, 1992). Myeloid neoplasia arises from primordial haematopoietic cells that originate myeloid lineage cells (erythrocytes, granulated leukocytes, monocytes and thrombocytes).…”

Section: Introductionmentioning

confidence: 99%

Histopathological and ultrastructural characteristics of myeloid leukosis in broiler chicken

Manzan

Baccaro

Ferreira

et al. 2006

Arq. Bras. Med. Vet. Zootec.

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“…Rous sarcoma virus is unique among retroviruses in being able to both replicate and transform quickly and efficiently (that is, acutely), although this is common for lentiviruses (including HIV). As a third group, other acutely-transforming retroviruses have picked up one or two oncogenes at the expense of the gag, pol and/or env genes, and therefore need another non-transforming virus (a so-called helper virus) to provide the structural proteins, and allow replication (Payne, 1992).…”

Section: Rous Sarcoma Virus and The Mhcmentioning

confidence: 99%

The importance of MHC for Rous sarcoma virus and Marek's disease virus—Some Payne‐ful considerations

Kaufman

Venugopal

1998

Avian Pathology

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In contrast to mammals, there are several viral diseases for which resistance and susceptibility are determined by particular chicken MHC haplotypes. At least one reason for this is that mammals express a multigene family of class I molecules, while common chicken haplotypes express only one class I molecule at high levels. We have determined the peptide-binding motifs for the some dominantly-expressed chicken class I molecules and found that they can explain the outcome of infections with the classic transforming retrovirus, Rous sarcoma virus (RSV). We have also found that the level of cell-surface expression of chicken class I molecules varies between MHC haplotypes, and that this correlates inversely with the MHC-determined resistance reported for classical Marek's disease virus (MDV). In this paper we consider two difficulties with these explanations. First, we examine the question of why the response to RSV depends on the MHC haplotype while the response to avian leukosis viruses (ALVs) does not. It would appear that the v-src gene present in RSV but not ALVs is responsible, and we find that, of three peptides derived from the v-src protein that bind the class I molecule of the resistant line CB, two differ quite significantly in sequence from the normal c-src protein sequence. Second, we examine the issue of resistance and susceptibility to MDV due to genes outside of the MHC. It is possible that such genes interact with the class I genes in the MHC, which puts the recent observation that a gene on chicken chromosome I that determines resistance and susceptibility to MDV may be the natural killer (NK) locus in an attractive perspective.

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“…The study of avian retrovirus receptors (see Young, 1998) to which Payne and Biggs have contributed so much (Payne, 1992), allowed us to delineate CD4 as the principal binding receptor for human cells (Dalgleish et al, 1984). However, it soon became apparent that CD4 was necessary, but insufficient for viral penetration (Maddon et al, 1986).…”

Section: Human Retrovirusesmentioning

confidence: 99%

The oncologist's debt to the chicken

Weiss

1998

Avian Pathology

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Our understanding of avian tumour virology has laid the groundwork for much basic cancer research. Most outstanding has been the delineation of oncogenes. These were first discovered in avian leukosis and sarcoma viruses, but are of fundamental importance in most types of non-viral cancer too, both in animals and humans. Avian tumour viruses gave us the tools to probe the complex signalling pathways in the cell that go awry in cancer. Avian retroviruses have also aided medical research in other ways: HIV infection is treated by anti-retroviral drugs directed against enzymes, such as reverse transcriptase, first discovered in chicken retroviruses. Endogenous viral genomes are becoming linked to normal development, to disease and to concern over xenotransplantation; again, the chicken provided the initial knowledge. Retroviral vectors used to deliver human gene therapy have borrowed extensively from natural oncogenic and genetically-engineered avian retroviruses. Marek's disease virus (MDV) has served as a model transforming lymphotropic herpesvirus for human lymphomas and lymphoproliferative disease caused by EpsteinBarr virus. Unravelling a novel human herpesvirus causing Kaposi's sarcoma also owes a debt to the chicken, not only to MDV, but also to the chorioallantoic membrane assay as a model for tumour angiogenesis.

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Biology of Avian Retroviruses

Cited by 61 publications

References 428 publications

Histopathological and ultrastructural characteristics of myeloid leukosis in broiler chicken

Histopathological and ultrastructural characteristics of myeloid leukosis in broiler chicken

The importance of MHC for Rous sarcoma virus and Marek's disease virus—Some Payne‐ful considerations

The oncologist's debt to the chicken

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