Extravascular haemolytic anaemia in chicks infected with highly pathogenic Marek's disease viruses.

Chicks were infected at 1 day of age with highly pathogenic AC-1 or RB-1B isolates of Marek's disease virus and 14 to 36 days post-exposure they were bled for haematocrits and euthanized. At necropsy, specimens were collected for light and electron microscopy. Both viruses caused significant reductions in packed cell volume (P<0.

Cytopathology caused by the AC-1 isolate of Marek's disease virus in the feather follicle epidermis.

The AC-1 strain of Marek's disease herpesvirus (MDV), recently isolated from an outbreak of Marek's disease in vaccinated chickens, was used for intraperitoneal inoculation of one-day-old Single Comb White Leghorns. Chicks were necropsied 12 to 32 days post inoculation and skin was collected for electron microscopic studies. This paper focuses on early stages of MDHV development in feather follicle epithelial cells and on cytoplasmic changes that occur in formation and release of virus particles.

Response of meat-type chickens to infection with RAV-1 avian leukosis virus.

Meat-type and White Leghorn chickens were inoculated with the RAV-1 strain of avian leukosis virus at 1 day of age and the severity of infection was assessed by clinical illness, haematology and post-mortem findings. The following were examined from selected birds: histological section for chronic mononuclear myocarditis, immunohistochemically-stained sections of myocardium, spleen, bursa of Fabricius and kidney for group-specific viral antigen, and ultrathin sections of these tissues for virus particles by electron microscopy. The experiment was terminated at 115-122 days.

Chronic myocarditis and circulatory syndrome in a White Leghorn strain induced by an avian leukosis virus: light and electron microscopic study.

Specific-pathogen-free white leghorn chickens were inoculated at 1 day of age with avian leukosis virus (ALV, RAV-1). All chickens in Expt. 1, killed 33 or 64 days postinoculation, had focal chronic lymphocytic or lymphoplasmacytic myocarditis.

Importance of the medullary macrophage in the replication of lymphoid leukosis virus in the bursa of Fabricius of chickens.

Electron microscopy and immunocytochemistry were used to study the development of lymphoid leukosis virus infection in the bursa of Fabricius of experimentally infected chicken embryos and chickens. In embryos infected at 7 days of incubation and killed 10 days later, virus particles and group-specific viral antigen were confined mainly to the connective tissue of the lamina propria of the bursal mucosal folds; a few developing follicles had discrete virions and group-specific antigen between cells. In chickens infected at 1 day of age, infection (as determined by use of electron microscopy and immunocytochemistry) was maximal in 1- to 4-month-old birds, and the greatest concentration of virus and group-specific viral antigen was in the medulla of the follicles.