R. E. Luginbuhl

Characterization of avian encephalomyelitis virus (an avian enterovirus).

Physical, chemical, and serologic tests demonstrated no significant differences between the laboratory strain of avian encephalomyelitis virus (AEV) and 19 field isolates. The average number of passages necessary for adaptation of the virus to produce lesions in embryos was 12. Embryo-infective-dose50 of adapted field isolates ranged from log 104.2 to 106.0/ml. The virus possessed no essential lipid, was heat resistant for the most part, and stabilized to effect of heat by magnesium cations. It was resistant to acid (pH 2.8), pepsin, and deoxyribonuclease, and affected slightly by ribonuclease. As determined by density-gradient centrifugation, the virus had a specific gravity of 1.33, similar to the findings with other RNA viruses without essential lipid. Virus-neutralization tests showed all field isolates to be serologically related to the laboratory virus. The virus could not be propagated in cell-culture systems from simian, human, bovine or avian sources, and does not hemagglutinate red blood cells of several species. The virus is classified as an enterovirus (picornavirus) by classification schemes.

Studies on avian encephalomyelitis IV. Early incidence and longevity of histopathologic lesions in chickens.

A field strain of avian encephalomyelitis virus, neutralized by hyperimmune serum produced against the Van Roekel strain, was introduced per os into susceptible 1-day-old chicks. Clinical signs were observed as early as 12 days postinoculation, and all chicks had recovered by the 26th day. Histopathologic lesions were observed as early as 8 days postinoculation and in sections taken from the 28th day to the 56th day. Only 2 of 21 birds sectioned from 63 to 105 days postinoculation had histopathologic lesions of AE in the brain, the organ most highly involved with this neurotropic strain.

Compared antibodies for Rous sarcoma virus in chicken serum and egg yolk with the metabolism inhibition test.

Rous sarcoma virus antibodies (RSVA) in chicken serum have been studied by a number of investigators (1,2,3,5,9). There is evidence that different forms of the leukoses are related to chicken sarcoma, and it is also possible that sarcomas and different forms of the leukoses constitute a family of related neoplasms. Since it appears that Rous sarcoma virus is closely related to other leukosis viruses, methods for the detection of RSVA have been employed to indicate the presence of related viruses. Rubin (8) developed an in vitro test in tissue culture, Sarma (10) described a tube neutralization test, and Calnek (4) a plate test. Kottaridis et al. (6) recently developed a metabolism inhibition test (MIT) for RSVA in chicken serum. The present report describes the detection of antibodies to Rous sarcoma virus in egg yolk by the MIT and compares antibody titers in serum with titers in egg yolk.

Synthesis, cytopathogenicity, and modification of avian encephalomyelitis virus (AEV) in chick kidney cell culture.

Summary Virus synthesis, cytopathogenicity, and modification of virulence for chicks, of AEV in chick kidney cell culture after 10 serial passages, have been described. The cell culture virus has been identified by histopathologic changes in inoculated chicks and virus neutralization tests in a cell culture system. The possible application of the findings are discussed.

Marek's disease. IV. Antigenic components demonstrated by the immunodiffustion test

Pappenheimer et al. (8) suggested that the causative agent of Mareks disease was a virus, although they were unable to reproduce the disease with cell-free material. In the past few years, different agents which cause Mareks disease upon inoculation into young chicks have been isolated by several investigators (2,3,9). Kottaridis et al. (7) reported growing in cell culture of chicken embryo fibroblasts (CEF) an agent which produced the disease upon inoculation into chicks. This agent produced a cytopathic effect (CPE) in cell cultures, and was propagated in fresh cultures by passing cells or supernatant fluids from the infected cell cultures. Churchill and Biggs (4) reported herpes virus-like particles in cell cultures inoculated with Mareks disease tumor cells. Kottaridis and Luginbuhl (6), in fluorescent antibody studies with Mareks disease, demonstrated specific antigen in cells of CEF inoculated with the Conn-A agent of Mareks disease and in bone marrow cells from infected birds with the same agent and with the JM strain. The present report is a continuation of antigenic studies with the Conn-A by the immunodiffusion test.

Antibodies for Newcastle disease virus and Mycoplasma gallisepticum in sera from domestic chickens and game fowl of Kenya.

Studies by one of the authors (2) present serological evidence for infection with a member or members of the group A (1) sarcoma-leukosis viruses in Kenya which indicate that they maintain themselves as endemic infections under natural conditions in a variety of game fowl as well as chickens running free in local villages in remote areas of the African bush country. Representative sera of those collected were examined for the presence of antibodies to Newcastle Disease virus (NDV) and Mycoplcsma gallisepticum (MG), using the hemagglutination-inhibition test for NDV and the agglutination test for MG in order to establish the infection with these agents in the areas studied.

Simplified Way to Cultivate Chick Kidney Cells and Maintain the Culture without Serum

Chick kidney fragments were easily dispersed after incubation in trypsin solution for 1 hour at room temperature. The centrifuged cells were resuspended in Melnicks growth medium, diluted to 100 ml for each pair of kidneys, and seeded at 1 ml per tube. The cultures were maintained for 7 days or longer in the medium modified by replacing the serum with tryptose.