Interferon immunomodulation in domestic food animals

Rapid transplacental infection with bovine pestivirus following intranasal inoculation of ewes in early pregnancy

Despite the importance of congenital viral infections in both veterinary and human medicine, only limited experimental work has been carried out to elucidate the mechanisms involved in transplacental virus infections. To further an understanding of fetal infection with pestiviruses, the distribution of bovine pestivirus in the uterine and fetal tissues of ewes in early pregnancy, following a natural route of infection, was investigated. On the 18th day of pregnancy, nine ewes were inoculated by the intranasal route with 1 x 10(5) 50% tissue culture infective doses of an Australian isolate of noncytopathic bovine pestivirus (bovine viral diarrhea virus genotype 1). All ewes were ovariohysterectomized at approximately 100 hours postinfection. Samples from the reproductive tract and conceptus were examined histologically and tested for bovine pestivirus by nested reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry and for interferon-tau mRNA expression by nonnested RT-PCR. Although no histopathologic changes were observed in the maternal or fetal tissues, virus was detected in the reproductive tract of all nine ewes and in all of the conceptuses examined. At the time of surgery, only two of the nine ewes were demonstrably viremic. This study demonstrates that bovine pestivirus can spread from a natural site of infection to the ovine fetus within 4 days in the absence of maternal immunity and despite the presence of interferon expression in the reproductive tract.

Enhancement of Neutrophil Function by Ultrafiltered Bovine Whey

The objective of this work was to evaluate a proprietary ultrafiltered bovine whey product for its in vitro influence on the function of neutrophils from normal and dexamethasone-treated cattle, and for its in vivo influence on neutrophil function in periparturient dairy cows. The ultrafiltered bovine whey was produced by hyperimmunizing cows to various bacterial pathogens by intramammary injection, collecting and pooling the colostrum and milk for the first 3 wk after parturition, then separating and processing the whey through a filter with a nominal molecular mass cut off of 10,000 Da. In vitro treatment of neutrophils from normal calves with ultrafiltered bovine whey significantly increased neutrophil random migration, cytochrome C reduction, iodination activity, antibody-dependent cell-mediated cytotoxicity, and antibody-independent cell-mediated cytotoxicity. Cytochrome C reduction was the only neutrophil function parameter significantly enhanced by the in vitro treatment of neutrophils from dexamethasone-treated cattle with ultrafiltered bovine whey. In vivo treatment of periparturient cows with ultrafiltered bovine whey did not alter the total or differential leukocyte counts in the animals but did significantly increase the total erythrocyte counts. In vivo treatment with ultrafiltered bovine whey also significantly increased neutrophil iodination activity in the periparturient cows. Neutrophil iodination activity (a measure of the myeloperoxidase/hydrogen peroxide/halide antibacterial system) is a very potent bactericidal mechanism of neutrophils and has previously been shown to be suppressed in periparturient cows.

Effect of Baypamun on blood leucocytes in normal and dexamathasone treated goats

The aim of this study was to determine the effect of Baypamun on selected lymphocyte subpopulations and granulocyte phagocytic activity mediated by lectin-like receptors in goats of normal immune status and in goats experimentally immunosuppressed with dexamethasone. Eighteen goats in total were used. Blood samples were collected 24 h before immunomodulation and 5 and 10 days after immunomodulation. Animals in group I were immunostimulated with Baypamun for 2 days and immunosuppressed with Dexafort for the next 2 days. Animals in group II received Dexafort first and then Baypamun. The number of leucocytes in total and in subpopulations was determined by flow cytometry. Application of Baypamun before (group I) or after (group II) immunosuppression caused significant (P < 0.001) and lasting changes in the percentage of CD2+, CD4+ and CD8+ T cells. Significant but transient changes were observed in CD19+ (B) and WC1-N2+ (null) cells. Results show that application of Baypamun to modulate non-specific defence is advisable following immunosuppression (group I). When Baypamun was applied after immunosuppression (group II), although there was no reaction during the initial phase, an increase in the activity of cells responsible for non-specific immunity was noticeable after 10 days.

Antiviral and antiluteolytic activity of recombinant bovine IFN-omega1 obtained from Pichia pastoris

The gene coding for bovine interferon-omega1 (BoIFN-omega1) was recently cloned and expressed at high levels in the yeast Pichia pastoris. The recombinant BoIFN-omega1 protein shows antiviral activity in different cell lines and has an antiluteolytic effect in cyclic ewes. In this article, we describe a method for purification of BoIFN-omega1 expressed in the methylotrophic yeast P. pastoris and characterization of its activity in vivo. The recombinant protein secreted to the culture medium had low activity because of self-aggregation. BoIFN-omega1 was solubilized using urea and desalting and finally purified by ion exchange chromatography on Q-Sepharose Fast Flow. The yield of purified product was approximately 300 mg/L of fermentation culture, with a specific antiviral activity of 10(8) IU/mg. Its purity was at least 80%. The biologic characterization of purified BoIFN-omega1 was determined by induction of an antiviral state on ewes challenged with 100 lethal doses (LD) of Aujeszky virus and by the extension of the corpus luteum life span and interestrous interval in cyclic cows. Ewes treated with 2 x 106 IU/kg BoIFN-omega1 were protected from Aujeszky virus infection. In cows receiving an intrauterine infusion of 1 mg BoIFN-omega1, equally distributed between the two uterine horns, twice daily from day 14 to day 22 of the experimental estrous cycle, the lifespan of the corpus luteum (25 vs. 19 days) and the interestrous intervals (26 vs. 21 days) were extended when compared with a control group (p < 0.05). We show that recombinant BoIFN-omega1 purified from P. pastoris has high antiviral activity and is an effective antiluteolytic agent in cattle.