Antibody-dependent cell-mediated cytotoxicity and spontaneous cell-mediated cytotoxicity against cells infected with porcine transmissible gastroenteritis virus.

The objective of this study was to determine whether porcine peripheral blood leukocytes and intestinal intraepithelial leukocytes can mediate antibody-dependent cell-mediated cytotoxicity and spontaneous cell-mediated cytotoxicity against target cells infected with transmissible gastroenteritis virus. Peripheral blood leukocytes collected from six young adult pigs and intraepithelial leukocytes from a further five pigs were used as effector cells in chromium release assays against PK-15 cells persistently infected with transmissible gastroenteritis virus. Both peripheral blood leukocytes and intraepithelial leukocytes were capable of mediating antibody-dependent cell-mediated cytotoxicity and spontaneous cell-mediated cytotoxicity against PK-15 transmissible gastroenteritis cells. While the peripheral blood leukocytes mediated lower levels of specific 51Cr release in spontaneous cell-mediated cytotoxicity than in antibody-dependent cell-mediated cytotoxicity, the intraepithelial leukocytes were more effective in spontaneous cell-mediated cytotoxicity than antibody-dependent cell-mediated cytotoxicity.     

Reaction of goats to infection with infectious bovine rhinotracheitis virus

Intranasal exposure of goats to infectious bovine rhinotracheitis virus resulted in mild respiratory disease and virus reisolation from nasal secretions. No disease was produced in goats exposed to the same virus by the genital or ocular routes. There was serological evidence of contact transmission of infection from infected goats to cattle. Virus recrudescence was not detected in goats treated with dexamethasone two months after virus inoculation.     

Isolation of infectious bovine rhinotracheitis virus from a latently infected feral pig

Infectious bovine rhinotracheitis (IBR) virus was isolated from the trigeminal ganglion of a feral pig after dexamethasone treatment. Three pigs inoculated intranasally with the IBR virus did not respond clinically or serologically. The virus was re-isolated from tonsillar swabs from two animals on Post-Infection Day (PID) 3.     

Enhancement of infectious bovine rhinotracheitis virus replication with corticosterone

Infectious bovine rhinotrachetis virus (IBRV) progeny was increased ten to 12 fold in bovine turbinate (BT) cells treated with 10^?3 M corticosterone acetate (CCA) as demonstrated by plaque assay. Autoradiographic studies demonstrated an increased binding of ³H-corticosterone (³H-CS) in IBRV infected cells and the fractionation of labelled cells revealed 78–80% of the total hormone associated with the cytoplasmic components. Incorporation of ³H-uridine and ³H-valine precursors into cells treated with the hormone demonstrated up to 16-fold increase in RNA and protein synthesis which was inhibited by the addition of actinomycin D. The data suggest that increased rate of macromolecular synthesis in IBRV infected cells treated with the corticosteroid may result in the enhancement of virus production.     

Enhancement of infectious bovine keratoconjunctivitis by modified-live infectious bovine rhinotracheitis virus vaccine

The effects of a modified-live infectious bovine rhinotracheitis virus vaccine (administered ocularly or intranasally) on experimentally induced infectious bovine keratoconjunctivitis were evaluated. The modified-live infectious bovine rhinotracheitis virus vaccine was administered to 13 male Holstein calves (intranasally in 4 and ocularly in 9; day 0). Five calves were not vaccinated and served as controls. Calves were examined daily and, starting on day 4, Moraxella bovis was administered ocularly to all 18 calves once daily for 4 days. The eyes of all calves were assigned a clinical score, and the ocular secretions were evaluated for presence of infectious bovine rhinotracheitis virus and M bovis daily until day 19. The severity of the ocular lesions was estimated by scoring the lesions clinically and by determining the protein concentration, myeloperoxidase activity, and WBC count in the tears. By day 5, conjunctivitis, chemosis, and epiphora were observed in all of the calves vaccinated ocularly. The calves vaccinated intranasally developed conjunctival plaques, but did not develop chemosis or photophobia. All of the calves developed keratitis after inoculation with M bovis. The median lesion scores were greater in both groups of vaccinated calves than in the controls. Corneal perforations developed exclusively in the vaccinated calves. The frequency of M bovis isolation from ocular secretions was significantly (P less than 0.05) greater in the vaccinated calves than in the controls. The tears from the intranasally vaccinated calves contained the highest myeloperoxidase activity and WBC count. The mean protein concentration in the tears of vaccinated calves was not significantly different from that in tears of controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative studies of strains of infectious bovine rhinotracheitis virus isolated from latently infected calves

Three strains (479 C, 778 TL, 982 LE) of infectious bovine rhinotracheitis (IBR) virus isolated from latently infected calves were compared with the prototype strain of IBR virus (LA strain) in studies which included restriction endonuclease analysis, experimental infection, and reciprocal cross protection tests in cattle. From the restriction endonuclease analysis it appeared that the 3 "latent" viruses were derived from the same isolate, and that it differed slightly from the LA strain. However, latency does not seem to have affected the pathogenicity or the immunogenicity of the virus. This is demonstrated by the identical clinical and virologic response of calves subjected to experimental infection with the various strains under study, and by the finding that when the LA strain and a "latent" strain (982 LE) were tested in cross protection tests in cattle, they proved to be mutually protective.     

Survival of infectious bovine rhinotracheitis virus in stored bovine semen

No loss in the titre of infectious bovine rhinotracheitis virus was found during storage in semen at –196°C for 1 year.     

Reactivation of infectious bovine rhinotracheitis virus by transport

Transport was studied as a cause of reactivation of infectious bovine rhinotracheitis virus (Bovine herpesvirus-1; BHV-1) in heifers vaccinated 2-6 months before transport, using a double dose of the thermosensitive (ts) vaccine strain (Tracherine). Eight out of 19 animals showed ts strain re-excretion over a period of 1-3 days, beginning, in 5 out of the 8 heifers, the day after transport. In 14 other heifers, only sera were examined by sero-neutralisation: only 1 out of these 14 animals showed a rise in BHV-1 neutralising antibodies. Transport can therefore be considered as a stimulus of BHV-1 reactivation.     

Isolation of infectious bovine rhinotracheitis virus in Tanzania

Summary Infectious bovine rhinotracheitis (IBR) virus was identified for the first time in Tanzania. The virus isolations were made from cattle affected with respiratory diseases. Concurrent infection with foot-and-mouth disease was observed and enhanced the severity of the illness.

---

Sumario El virus de la rinotraqueitis infecciosa de los bovinos (I.B.R.) ha sido identificado por primera vez en Tanzania. Los aislamientos de virus fueron hechos de bovinos afectados con enfermedades respiratorias. Se observó infección concurrente con fiebre aftosa y este hecho exacerbaba la severidad de la enfermedad.

---

Résumé Ce virus a été isolé pour la première fois en Tanzanie, à partir de bétail atteint d'affections respiratoires. Cette maladie a sévi concurremment avec la fièvre aphteuse, ce qui explique sa sévérité.