Production and functional characterization of recombinant bovine interleukin-8 as a specific neutrophil activator and chemoattractant

Interleukin-8, a member of the chemokine family of cytokines, is a potent neutrophil chemoattractant in many non-rodent species. In this study, recombinant bovine interleukin-8 (rbIL-8) was expressed in bacteria as a glutathione-S-transferase fusion protein. The fusion protein was purified by glutathione-Sepharose affinity chromatography and recombinant rbIL-8 was eluted by cleaving with thrombin. The purified rbIL-8 molecule was approximately 8 kDa and was confirmed as authentic IL-8 by Western analysis. Recombinant bovine IL-8 induced specific dose-dependent in vitro chemotaxis of neutrophils at doses as low as 1.0 ng/ml, and this activity was inhibited by pre-treatment of rbIL-8 with a monoclonal antibody to ovine IL-8. Neutrophils exposed to rbIL-8 developed pseudopodia and became elongated as determined by microscopic analysis and flow cytometry. Injection of 3.3 ng to 3.3 microg of rbIL-8 into the skin of a normal calf induced dose-dependent recruitment of neutrophils but not eosinophils. Intravascular margination of neutrophils was obvious at the injection sites from 15 to 60 min after administration of rbIL-8, and extravascular neutrophil numbers increased steadily from 1 to 18 h after injection. Neutrophils with morphologic features of apoptosis were detected in these lesions at 18 and 30 h after injection, and this correlated with reduction in the number of dermal neutrophils. These results confirm unequivocally that bovine IL-8 functions as a neutrophil, but not an eosinophil, chemoattractant in vitro and in vivo.     

Pathogenesis studies with Australian bat lyssavirus in grey-headed flying foxes (Pteropus poliocephalus)

OBJECTIVE: To examine the susceptibility of the grey-headed flying fox (Pteropus poliocephalus) to Australian bat lyssavirus (ABL), and to provide preliminary observations on the pathogenesis of the disease in flying foxes. PROCEDURE: Ten flying foxes were inoculated intramuscularly with ABL, and four with a bat-associated rabies virus. Inoculated animals were observed daily, and clinical samples collected every 9 to 14 days. Animals with abnormal clinical signs were euthanased, and samples collected for histological, serological, virological and immunohistological examinations. At 3 months post inoculation (PI), all survivors were euthanased, and each submitted to a similar examination. RESULTS: Three ABL-inoculated flying foxes, and two rabies-inoculated animals developed abnormal clinical signs between 15 and 24 days PI. All three ABL-inoculated animals had histological lesions consistent with a lyssavirus infection, and lyssaviral antigen was identified in the central nervous system (CNS) of each. Virus was isolated from the brain of two affected animals. Of the rabies-inoculated flying foxes, both had histological lesions and viral antigen in the CNS. Virus was recovered from the brain of only one. None of the five affected flying foxes developed anti-lyssavirus antibodies, but, by 3 months PI, five of the seven ABL-inoculated survivors, and one of the two rabies virus-inoculated survivors, had seroconverted. The dynamics of the immune responses were quite variable. CONCLUSIONS: The response of flying foxes to ABL, administered by a peripheral route of inoculation, was similar to that of bats inoculated peripherally with bat-derived rabies viruses.     

FACIAL FIBROSARCOMA IN TWO COWS

Fibrosarcoma is a common tumor affecting bone, but is uncommon in cows, Reported here are two bovine cases of facial fibrosarcoma that were very invasive.     

Unicellular algae as a food for turbot (Scophthalmus maximus L.) larvae — The importance of dietary long-chain polyunsaturated fatty acids

The production of juvenile turbot in research and commercial practice still involves the use of live foods for the early larvae. The rotifer Brachionus plicatilis is used for the first few days followed by nauplii of the brine shrimp, Artemia salina. During this live food phase, the addition of live unicellular algae to the rearing tanks improves the growth and survival of the turbot larvae.Within 10 days of the start of feeding, large differences in growth rate become apparent depending on the presence or absence of particular algae. The use of Dunaliella tertiolecta in particular results in stunted growth and high mortalities. Evidence is presented in this paper that Dunaliella tertiolecta is not toxic, and that its failure to support turbot larval growth is probably due to a deficiency of long-chain polyunsaturated fatty acids. These compounds have been shown by other workers to be an essential dietary requirement in O-group turbot.