Pathogenesis of infectious bursal disease in embryonally bursectomized chickens.

The pathogenesis of infectious bursal disease (IBD) in intact chickens was compared with pathogenesis in chickens that had undergone embryonal bursectomy (EBX chickens), which were challenged at either 2 or 6 weeks of age. All EBX chickens were free of bursa remnants, and those challenged at 6 weeks of age failed to develop primary and secondary antibody responses to sheep red blood cells and bovine serum albumin. A direct fluorescent-antibody technique was used to study the course of infection in the bursa of Fabricius, spleen, thymus, cecal tonsils, and kidneys. EBX delayed but did not prevent the appearance of IBD-infected cells. Virus-positive cells were detected in the thymus of EBX chickens up to 18 days postinfection. Significantly more EBX chickens challenged at 6 weeks of age had hemorrhagic lesion in muscles and intestinal tract than comparable intact chickens had.

Comparative pathogenesis studies with oncogenic and nononcogenic Marek's disease viruses and turkey herpesvirus.

An apparently nononcogenic Marek's disease virus (SB-1) and turkey herpesvirus could be readily isolated from spleen, bursa of Fabricius, thymus, and peripheral blood lymphocytes of chickens beginning 4 to 6 days after inoculation, but unlike infections with two isolates of oncogenic Marek's disease virus (JM-10 and CU-2), virus replication in these cells was rare, and necrosis in the organs was essentially absent. Splenic enlargement was observed regularly during the first 4 to 11 days after inoculation, and Marek's disease tumor-associated surface antigen was observed on splenic and other lymphocytes in the four viral inoculation groups. Cellular cytotoxicity of splenic lymphocytes was demonstrated in vitro with cultured Marek's disease tumor cells (MSB-1 lymphoblastoid cell line) as the target in a chromium-release assay. The four viral infections induced sensitized lymphocytes.

An epidermal papilloma of the Atlantic samon II: Ultrastructure and etiology.

Ultrastructure of the Atlantic salmon papilloma was studied, and virus isolation was attempted. The papilloma cells were similar to normal epidermis in having interdigitating cell membranes with desmosomes. The nuclei, however, were more regular in shape than normal epidermal nuclei and the chromatin tended to be marginated and clumped. No cytopathic viral agents were isolated.

An epidermal papilloma of the Atlantic salmon I: Epizootiology, pathology and immunology.

Papillomatosis of Atlantic Salmon (Salmo salar) was studied with regard to epizootiology, gross and histologic pathology, and host response. It was found to be a condition of parr in their second summer, but also occasionally of young adult fish (smolts and grilse) which have adapted to salt water. The lesion was plaque-like to papillomatous and consisted of stratified squamous epithelium with supporting stroma. Immunologic findings tended to support histologic observations that the lesion was ultimately sloughed as a result of a cell mediate immune response.

Spontaneous renal disease in Louisiana armadillos (Dasypus novemcinctus).

Renal lesions were present in 34 (68%) of 50 armadillos (Dasypus novemcinctus) collected for a survey of the prevalence of leptospires in Louisiana wildlife. The renal lesions were not associated with elevations in the renal function tests of blood urea nitrogen or serum creatinine or with consistent serologic or cultural evidence of leptospires.

Predicting blood lead concentrations from environmental concentrations.

A method is presented by which blood lead concentrations can be estimated from environmental concentrations using a multipathway analysis. For the ingestion and dermal uptake pathways the incremental increase in blood lead concentration is estimated as the product of the concentration in the relevant medium, a medium-specific contact rate, and an empirically determined ratio between intake and blood level. The inhalation pathway omits the contact rate and uses a ratio between the concentration in blood and the concentration in air. Model outputs corresponding to various input parameters are presented, and some of these are compared with outputs from the U.S. Environmental Protection Agency's Lead Biokinetic/Uptake model, Lead 5.