An international comparison of different laboratory tests for the diagnosis of bovine leukosis: suggestions for international standardization

A collaborative study was conducted to compare the detection limit of different laboratory tests for antibodies against bovine leukemia virus (BLV). Serum and milk samples were tested in agar gel immunodiffusion (AGID), different modifications of indirect ELISA, blocking ELISA and ELISA procedures using monoclonal antibodies to BLV gp51 or BLV p24. The detection limit of reference serum E4 diluted 2-fold in negative serum gave a median value of 1:16 in AGID, indirect ELISA, and monoclonal ELISA p24, 1:128 in monoclonal ELISA gp51, and 1:1024 in blocking ELISA. The detection limit of a 4% immunoglobulin preparation of E4 diluted in negative milk showed median values of 1:800 in indirect ELISA, 1:1000 in monoclonal ELISA, and 1:2400 in blocking ELISA. None of the ELISA procedures could detect all the positive individual milk samples diluted 1:50. The AGID test is the official reference test for detection of antibodies against BLV. Reference serum E4 diluted 1:10 in negative serum must be scored positive in the AGID test. It is suggested that an international reference serum standard be established rather than an official recommendation of a particular ELISA test.     

Spatial visualization of progressive states of maturing lentivirus.

Progressive states of maturing lentivirus: maedia visna virus (MVV) and human immunodeficiency virus (HIV), respectively, have been visualized by 2-D electron microscopy and by 3-D electron microscopic tomography. A major fraction of MVV and a low percentage of HIV appear as immature particles 4 to 5 days post virus infection. Upon budding the gag-precursor material is densely packed inside the external envelope. After virus release the major portion of precursors is assembled within an approximately 25 nm thick layer directly attached to the envelope. Structural maturation of the core is different for the two viruses. Pleomorphic cores are observed in mature MVV in contrast to structurally defined cores of HIV. The latter are principally cone-shaped, spanning the entire diameter of the virion with a 40 to 60 nm wide free end and an approximately 20 nm narrow end attached to the envelope with a core-envelope-link.     

Meat quality in broilers affected with inflammation of the feather follicles

Broilers with feather follicle inflammation and birds free of this disorder were selected from the broiler chickens kept on plastic (bralen-)coated metallic slats. Both groups of broilers were killed on a sanitary slaughter line and the samples of breast and thigh muscles were analyzed for the basic composition and characteristics of the metabolism of nitrogenous and lipidic components. The content of individual amino acids in the muscles and the proportion of fatty acids in the intramuscular fat of broilers were determined for the evaluation of nutritive value. The samples of the affected spots of skin and samples of organs (liver) were subjected to microbiological examination. The resultant finding represented the common mesophilous microflora. No substantial statistically significant differences in chemical characteristics were found between the two groups. It follows from the results that the inflammation of feather follicles is a local skin disorder with no effect on the quality of the meat.     

N-acetyl-beta-D-glucosaminidase and antitrypsin in subclinically infected quarter-milk samples: effect of bacteria and hemolysins, lactation stage, and lactation number

Interrelationships between N-acetyl-beta-D-glucosaminidase (indicating cellular damage) and antitrypsin (indicating increased permeability between the blood and milk compartments) were evaluated in 1,411 quarter-milk samples collected during routine herd surveys. N-Acetyl-beta-D-glucosaminidase was antitrypsin, whereas, in more severe mastitis, antitrypsin had a more constant deflection. The sensitivity of both determinants was associated with the virulence of bacteria. Production of bacterial hemolytic toxins was associated with a significant increase in both determinants. Penicillinase production by staphylococci was associated with selective increases of antitrypsin.