Biomedical subjects
Publications and source records attributed to R S Spendlove.
The FBS Control is designed to assist cell culture scientists who have been frustrated with lack of consistency in FBS lots. Continued use will reduce the time and expense needed in classical lot selection methods.
The infectivity of a bovine rotavirus was enhanced 140-, 8-, and 3-fold, respectively, by trypsin, protease, and lactase. Ficin, carboxypeptidases A and B, lysozyme, and beta-galactosidase had little effect on the infectivity. Chymotrypsin caused a threefold decrease in the infectivity. Trypsin acts directly on the rotavirus and not on the host cell.
Titers of bovine rotavirus in excess of 10(9) immunofluorescent infectious units per ml of culture fluids have been produced, using trypsin treatment of the virus. Infectivity of preparations of the virus can be increased with as little as 1 ng of trypsin per ml, with maximum increases of 1 to 2 log10 with 1 microgram of trypsin per ml. The virus grows to titers in excess of 10(5) immunofluorescent units per ml in MDBK, LLC-MK2, MA-104, and HeLa cells. When MDBK cells are infected with a multiplicity of infection of 20, maximum yields of cell-associated, trypsin-enhanceable virus are obtained 4 to 8 h postinfection. Maximum yields of cell-free, trypsin-enhanceable virus are produced 16 to 20 h postinfection. The results presented here indicate that trypsin can be used to produce high-titer stocks of bovine rotavirus.
The nucleic acids of neonatal calf diarrhea virus were characterized by isopycnic centrifugation in Cs2SO4, electron microscopy, ultraviolet absorbance temperature profiles and polyacrylamide gel electrophoresis. These studies indicated that the neonatal calf diarrhea virus genome consists of 11 segments of double stranded RNA with a total molecular weight of 10.75 million daltons.
Thirty-four calf and five infant fecal specimens were tested for the neonatal calf diarrhea virus (NCDV) and for the reovirus-like infantile diarrhea agent; respectively. The procedures used were the fluorescent virus precipitin test and immune electron microscopy. Fourteen of the calf stools contained detectable NCDV, and four of the five infant stools contained the reovirus-like human agent. Infectious NCDV was detected in four of the 34 calf fecal specimens when Madin-Darby bovine kidney cell cultures that had been inoculated with supernatant fluids from stool suspensions were stained with fluorescent antibody. The 20 calf stools that did not have detectable virus were examined for the bovine corona diarrhea virus. Coronavirus was found in two of these specimens.
Lesions of hamster fetal neuraxial tissues, characterized by multifocal and coalescent zones of hemorrhage, edema, and necrosis in the cerebral mantle, brainstem, and spinal cord, were observed in experiments designed to test the teratogenicity of potato preparations. Retrospective and prospective data indicated, however, that the potato preparations were not responsible but that the disease occurred spontaneously in the colony and was associated with direct breeding contact of virgin females with certain males. Observations suggest that an infectious agent may be responsible, but no agent was recovered. Immunofluorescence assay of inoculated cultures indicated that reovirus was not present in affected fetal tissues.
Infectious pancreatic necrosis virus was stable for 10 days at 4 C in stream and well water, after which the virus had a half-life of 7.5 days. At 15 C, the virus was stable for 5 days, and then had a half-life between 5 and 6 days. Viral antigen in infected cells developed much more slowly at 4 C than at 20 C. Infected cells released infectious viral particles at temperatures as low as 4 C. Nutrition had a greater effect on the production of infectious virus at 4 C than at 20 C.
A fluorescent virus precipitin test (FVPT) for the serologic identification of small particulate antigens such as viruses has been described. The test has several advantageous characteristics: (a) It is probably as sensitive as any serologic test (i.e., aggregates with dimensions of 0.2 mum are detectable; therefore, complexes containing as few as three large viruses would give a positive test). (b) Cultivation of the virus is not required. (c) Since an indirect test can be used, only a single fluorescent conjugate is needed to permit the detection of a number of viruses. (d) The indirect test can be used to detect antiviral antibody. (e) The FVPT is rapid and reliable. (f) Its simplicity should enhance its general acceptance and application.
A reliable plaque assay procedure has not yet been described for the neonatal calf diarrhea virus. Therefore, a previously developed immunofluorescent cell counting procedure was adapted to assay this virus. Adsorption of the virus to bovine kidney cells plateaued at 60 minutes. The optimal staining time was between 20 and 24 hours postinfection. Infected cells begun releasing from the coverslips if the cultures were incubated longer than 24 hours. This procedure has proven successful with virus grown in cell culture as well as virus present in fecal samples.