The commercially important neoplastic diseases of poultry are Marek's disease, which is caused by a herpesvirus, and the avian leukoses and reticuloendotheliosis, which are caused by retroviruses. These diseases are responsible for economic loss due to both mortality and depressed performance. Marek's disease virus (MDV) and avian leukosis viruses (ALVs) are prevalent throughout the world, and ...

Avian leukosis viruses (ALVs) in poultry may induce a variety of deleterious effects including tumors, increased mortalities, growth retardation and decrease in egg size and production that led to considerable economic losses. The identification of avian leukosis viruses (ALVs) in imported Marek’s disease (MD) vaccines has raised concern about transmission of these retroviruses to vaccine recip...

AIM The purpose of this study was focused on the identification of tumor diseases in turkeys on the basis of a detailed description of epidemiological features, clinical signs, lesions, and histopathological changes. MATERIALS AND METHODS Outbreak of a tumor disease in turkeys was investigated in various regions of Eastern Algeria. Four turkeys' flocks aged from 17 weeks were affected, result...

White leghorn chickens from seven 15.B congenic lines (genetically similar except for genes linked to the major histocompatibility complex [MHC] B haplotype) and two Line 0.B semicongenic lines were infected at hatch with strain ADOL Hc-1 of subgroup J avian leukosis virus (ALV-J). At 5, 8, 16, and 36 wk of age, chickens were tested for viremia, serum-neutralizing antibody, and cloacal shedding...

Reverse transcriptase (RT) activity has been detected recently in all chicken cell-derived measles and mumps vaccines. A study of a vaccine manufactured in Europe indicated that the RT is associated with particles containing endogenous avian retrovirus (EAV-0) RNA and originates from the chicken embryonic fibroblasts (CEF) used as a substrate for propagation of the vaccine. We investigated the ...

Avian leukosis virus (ALV) is known to cause several neoplastic conditions in chickens, such as B-cell lymphomas, myelocytomas, erythroblastosis, and other types of neoplasia including osteopetrosis. We describe herein the identification of unique ALV-related proviral DNA sequences in an archived chicken bone affected with osteopetrosis. The osteopetrotic bone was obtained from an affected 46-w...

In human immunodeficiency virus type 1-infected cells, the efficient expression of viral proteins from unspliced and singly spliced RNAs is dependent on two factors: the presence in the cell of the viral protein Rev and the presence in the viral RNA of the Rev-responsive element (RRE). We show here that the HIV-1 Rev/RRE system can increase the expression of avian leukosis virus (ALV) structura...

DESCRIPTION YF-VAX®, Yellow Fever Vaccine, for subcutaneous use, is prepared by culturing the 17D-204 strain of yellow fever virus in living avian leukosis virus-free (ALV-free) chicken embryos. The vaccine contains sorbitol and gelatin as a stabilizer, is lyophilized, and is hermetically sealed under nitrogen. No preservative is added. The vaccine must be reconstituted immediately before use w...

To study the effect of intron size on splicing efficiency we have varied the size of the avian leukosis virus (ALV) env mRNA intron in a cloned ALV genome. This was accomplished by deletion of ALV sequences or insertion of phage lambda DNA. The effect of these modifications on splicing was analyzed by microinjection of the modified clones into RSV(-) chicken cells. Viral env mRNA when transcrib...

Avian leukosis viruses (ALVs) are common in many poultry flocks and can be detected using an enzyme-linked immunosorbent assay or any other test designed to identify p27, the group-specific antigen located in gag. However, endogenous retroviruses expressing p27 are often present and can be confused with exogenous ALVs. A more specific and informative assay involves targeting the variable envelo...