A new subgroup of avian leukosis virus (ALV), designated subgroup J, was identified recently. Viruses of this subgroup do not cross-interfere with viruses of the avian A, B, C, D, and E subgroups, are not neutralized by antisera raised against the other virus subgroups, and have a broader host range than the A to E subgroups. Sequence comparisons reveal that while the subgroup J envelope gene i...

Previously, we have demonstrated that bridge proteins comprised of avian leukosis virus (ALV) receptors fused to epidermal growth factor (EGF) can be used to selectively target retroviral vectors with ALV envelope proteins to cells expressing EGF receptors. To determine whether another type of ligand incorporated into an ALV receptor-containing bridge protein can also function to target retrovi...

Avian leukosis virus (ALV) subgroup J is thought to have emerged through a recombination event between an unknown exogenous ALV and the endogenous retrovirus elements designated EAV-HP. All EAV-HP elements identified to date in the chicken genome show large deletions, including that of the entire pol gene. Here we report the identification of four segregating chicken EAV-HP proviruses with comp...

It is a pleasant change to write about viruses that might have emerged but haven't. In this issue, Hussain and colleagues at the Centers for Disease Control and Prevention, the U.S. Department of Agriculture, and Harvard University report that recipients of measles, mumps, and rubella (MMR) vaccine show no evidence of infection by endogenous avian retroviruses, even though viral genomes and rev...

Avian leukosis virus (ALV) has been used as a model system to understand the mechanism of pH-independent viral entry involving receptor-induced conformational changes in the viral envelope (Env) glycoprotein that lead to membrane fusion. Here, we report the unexpected finding that ALV entry depends on a critical low pH step that was overlooked when this virus was directly compared to the classi...

The aim of this study was to investigate the presence of antibodies to ALV-J in broilers and broiler breeders. For this, 5 broiler units and 1 broiler breeding unit in the Marmara region were visited. Seventy 4-6 -week-old chicks from the broiler units, consisting of 14 chicks from each broiler unit, were selected. Seventeen chickens from the broiler breeding unit were also selected. The chicks...

So-called fowl glioma is a retroviral infectious disease caused by avian leukosis virus subgroup A (ALV-A). We determined the complete nucleotide sequence of the virus genome. The full-length sequence was consistent with a genetic organization typical of a replication-competent type C retrovirus lacking viral oncogenes. The coding sequences were well conserved with those of replication-competen...

The critical time of avian leukosis virus subgroup J (ALV-J)-mediated immunosuppression was determined by body weight, relative immune organ weight, histopathology, and presence of group specific antigen and antibodies in specific pathogen-free (SPF) chickens. CD4(+) and CD8(+) cell activity in the spleen, total and differential leukocyte counts in blood, and viral RNA levels in spleen were mea...

The aim of this study was to detect and characterize the endogenous ALVs in cell associated MD vaccine. Chicken embryo fibroblast cell associated Marek’s disease vaccine was tested for possible contamination with Avian Leukosis Viruses (ALVs). Initially the vaccine cell lysate was tested for presence of group specific antigen (p27) of ALVs by ELISA and found positive for GSA. Subsequently total...

Avian leukosis virus (ALV) is a retrovirus that causes tumors in avian species, and its vertical and horizontal transmission in poultry flocks results in enormous economic losses. Despite the discovery of specific host receptors, there have been few reports on the modulation of viral susceptibility via genetic modification. We therefore engineered acquired resistance to ALV subgroup B using CRI...