The evaluation of AKR leukemia virus purity: the requirement for both velocity and isopycnic centrifugation methods

The protein pattern of PMF virus, a type-D retrovirus from malignant permanent human cell lines

The protein pattern of a type-D retrovirus (PMFV) isolated from and propagated in human cell lines has been investigated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Staining with Coomassie blue and labeling with 14C-leucine/14C-lysine revealed five viral polypeptides with molecular weights of 10,000, 12,000, 15,000, 25,000, and 68,000. The 68,000 D-protein was shown to be a glycoprotein by incorporation of 3H-glucosamine and the 15,000 D-protein was identified as a phosphoprotein. By comparing PMFV with the closely related Mason-Pfizer monkey virus (MPMV) in co-electrophoresis experiments no clear difference was detected in viral 14C-leucine/14C-lysine profiles. The viruses differ, however, with respect to their glycoprotein patterns. A glycoprotein corresponding to the gp20 of MPMV has not been detected in PMFV irrespective of the cell line used for propagation of viruses.

Use of trypsin for rapid and efficient purification of murine sarcoma and leukemia virus

A method is described for purification of MSV-MuLV from culture supernatant of chronically infected 78A,1 rat embryo cell line. This method involves direct polyethylene glycol-NaCl precipitation of the low speed supernatant of culture fluid followed by digestion of the pellet with trypsin. This procedure efficiently disrupts large aggregates which normally entrap most of the virus. Highly purified virus can be obtained in very good yield by a combination of sedimentation velocity and isopycnic centrifugation : yields up to 100 A280 units (17 mg of protein) of purified virus per liter of culture fluid can be observed. This procedure appears well suited for large scale isolation of virion associated enzymatic activities.

Polypeptide patterns of infectious bronchitis virus serotypes fall into two categories. Brief report

Molecular weights of six major polypeptides of infectious bronchitis virus (IBV) are: 1. 75,000; 2. 50,000; 3. 45,000; 4. 35,000; 5. 28,000 or 24,000, and 6. 22,000 dalton. According to the mobility of protein 5 the polypeptide patterns of IBV serotypes fall into two main categories.