Structural proteins of bovine parainfluenza-3 virus.

Six structural proteins of bovine parainfluenza-3 virus (PI-3V) labeled with [35S]-methionine could be resolved by polyacrylamide gel electrophoresis (PAGE). Five structural proteins of this virus had been previously reported. The 6 proteins found in this study were: L, a 180,000 (180 kD) molecular weight (MW) large protein; P, 83 kD phosphoprotein; HN, 69 kD hemagglutinin-neuraminidase glycoprotein; NP, 66 kD nucleocapsid protein; F, 55 kD fusion glycoprotein; and M, 38 kD matrix protein. Selective labeling with [2-3H]-mannose revealed only HN and F glycoprotein bands. A cellular actin protein (43 kD), associated with many enveloped viruses, was also found as a seventh protein in bovine PI-3V.

Immunoferritin and immune electron microscopic study of bovine herpesvirus strain DN-599.

Intracellular antigens of strain DN-599 bovine herpesvirus were detected in the cytoplasm and the nucleus of infected bovine embryonic kidney cells by the indirect immunoferritin (IF) technique. Specific tagging was observed in viral envelope and capsids. Aggregates of viral particles heavily coated with antibody were seen by immune electron microscopy (IEM).

Antibody and complement-mediated cytotoxicity for bovine parainfluenza-3 virus-infected cells.

An antibody-complement-mediated cytotoxicity assay was employed to determine whether susceptible host cells infected with bovine parainfluenza-3 virus could be destroyed by the humoral immune mechanism. The cytotoxicity assay yielded 21.5% to 76.9% specific release of 51Cr with sera collected from calves 28 days after inoculation with the virus. A multiplicity of infection of 5, a postinfection period of 2 days, an antibody dilution of 1:10, and an incubation period of 12 hours with antibody and complement were found to be optimal for this assay.

Effect of 2-deoxy-D-glucose and glucosamine on bovine respiratory syncytial virus.

2-Deoxy-D-glucose (2-dG) and glucosamine reversibly inhibited the replication and cytopathic effects of bovine respiratory syncytial virus in bovine turbinate cell cultures. The inhibitors were effective when added up to 12 hours after cell cultures were inoculated. Their effectiveness decreased as the time between inoculation of cells and drug treatment lengthened. The sugars did not inactivate the virus directly, and inoculation of drug-treated cells in drug-free medium produced normal yield of virus. Mannose fully reversed the inhibitory effects of 2-dG, but was ineffective for glucosamine. Protein synthesis was necessary for production and release of infective virus after removal of 2-dG and glucosamine blocks. Electron microscopic studies revealed a large amount of bovine respiratory syncytial virus production with characteristic spike-like projections on the viral envelopes in the absence of these inhibitors. There was a drastic reduction in the number of mature virions produced in inhibitor-treated bovine turbinate cells, and the virions lacked the characteristic surface projections.

Isolation and characterization of adeno-associated viruses from bovine adenovirus types 1 and 2.

Hemagglutinating DNA viruses of 20 nm diameter were isolated from bovine adenovirus types 1 and 2. The isolates were heat stable, chloroform resistant, and defective. Their densities were 1.38 to 1.39 g/cm3, and they were found to be serologically identical to the bovine adeno-associated virus strain X7. A partial antigenic relationship was found between these and the canine adeno-associated virus.

Experimentally induced respiratory syncytial viral infection in calves.

Calves exposed by intranasal (IN) or intratracheal (IT) or both routes of inoculation to bovine respiratory syncytial (BRS) virus had a transient increase in body temperature for 2 days. Histopathologic changes indicative of pneumonia, along with multinucleated giant cells, were observed in alveolar lumen. The virus was recovered from infected calves, and their serologic response was poor. In a limited serologic survey with 100 serums from cattle in Maryland, low levels of serum-neutralizing (SN) antibody to the virus were prevalent in 38% of the serums.

Blastogenic response of swine lymphocytes in whole blood, purified blood, spleen cell, and lymph node cell cultures with concanavalin A and phytohemagglutinin.

Microcultures of swine whole blood, purified blood lymphocytes (PBL), spleen cells, and lymph node (LN) cells were tested for stimulation by concanavalin A (conA) and phytohemagglutinin (PHA). A cell concentration of 2 x 10(6)/ml and a 1:20 dilution of whole blood were needed for optimal stimulation of conA and PHA. Optimal stimulation of whole blood lymphocytes (WBL) and LN cells was obtained by 20 micrograms of conA/ml, but 10 micrograms/ml of this mitogen was adequate for spleen cells. The PBL and LN cells were optimally stimulated by 20 microliters of PHA/ml, but 80 microliters and 40 microliters/ml of this mitogen were required for stimulating the whole blood and spleen cells, respectively. Four days' incubation was needed for maximal blastogenesis of WBL with conA. This could be achieved after 3 days' incubation with PBL and spleen and LN cells. Whole blood and spleen cells were stimulated by PHA after 3 days' incubation, but PBL and LN cells required 4 days' incubation. Reproducibility, sensitivity, and comparison of various cultures were discussed.

Chemotherapeutic value of 2-deoxy-D-glucose in infectious bovine rhinotracheitis viral infection in calves.

Daily injection of 2-deoxy-D-glucose (2-dG) had no protective effect against respiratory tract infection in calves caused by infectious bovine rhinotracheitis virus. It also did not reduce the severity of this infection. Ocular instillation of the drug, however, markedly reduced the severity of viral-induced conjunctivitis and keratoconjunctivitis. The drug was effective when given at the time of ocular infection or after clinical conjunctivitis developed.

Virologic study of the reproductive tract in dairy cows.

From Aug 1, 1979 to Aug 15, 1980, a total of 624 samples were collected from the vaginas, cervices, and uteri of 208 dairy cows 30 to 37 days after parturition. An additional 90 samples were collected from the reproductive tracts from 30 of the 208 cows. The 30 cows had aborted or were repeat breeders. Samples from cows that had aborted were collected within a week after clinical abortion or immediately after rectal palpation revealed subclinical abortion. All samples were tested for the presence of cytopathogenic viruses. All samples were negative.

Effect of human interferon on vesicular stomatitis virus released from bovine embryonic kidney cells.

Human lymphoblastoid interferon (IFN) had an antiviral activity in bovine embryonic kidney cells that resulted in the release of vesicular stomatitis virus (VSV) particles with decreased infectivity. The inhibition was dose dependent and the cells were highly sensitive to human IFN. Examination of the proteins of VSV released from bovine cells after IFN treatment showed a reduction in the glycoprotein. Electron microscopic studies revealed a large number of VSV particles with characteristic spike-like surface projections released from nontreated cells. There was a reduction in the number of mature virions produced in IFN-treated cells and the virions lacked the characteristic surface projections.

Effect of levamisole on induced bovine viral diarrhea.

The effect of levamisole in calves experimentally infected with bovine viral diarrhea virus was evaluated in a double-blind study. The infection was mild and there was no difference in severity of infection or speed of recovery between levamisole-treated and 0.9% NaCl solution-treated (control) calves. Also, the serum antibody titers and viral recovery data of these calves were comparable. The white blood cell counts were consistently higher in the treated group than in the control group, with the difference peaking on postinoculation day 15. The detection of marked lymphopenia in control calves but not in levamisole-treated calves indicated a potential use of levamisole in bovine viral diarrhea.