ABSTRACT. Protective efficacy of Actinobacillus pleuropneumoniae extracellular hemolytic toxins, RTX-toxin I (Apx I) and Apx II, was evaluated in pigs. The hemolysins were purified from culture supernatant of A. pleuropneumoniae strain HA-337, serotype 1 by immunoaffinity chromatography using a monoclonal antibody specific for Apx I or Apx II as ligand. Four pigs were vaccinated with the purified hemolysins adsorbed on aluminium phosphate gel adjuvant. Four pigs of a control group were given placebo. Hemolysinneutralizing antibodies were detected only in vaccinated group after booster injection. One of four control pigs died following an aerosol challenge with the homologous strain, and three surviving pigs developed serious clinical signs of pneumonia and had extensive lung lesions. In contrast, there was no mortality in vaccinated group. Only transient hyperthermia was observed in two vaccinated pigs after challenge. At necropsy, two vaccinated pigs had slight localized pulmonary lesions, though the remaining two had no lung lesions at all. These results indicate that the hemolysin vaccine made of Apx I and Apx II has good protective activity against swine pleuropneumonia caused by A. pleuropneumoniae serotype 1. -KEY WORDS: Actinobacillus pleuropneumoniae, Apx, immunoaffinity chromatography, vaccine.

ABSTRACT. Holstein bullocks were used in this study to compare the effectiveness of five commercial parenteral fluids (saline IS, Hartmann's IH, 5%-glucose 5G, Ringers IR, and 1/2 Ringer's and 2.5% glucose combination solutions RG) in correcting the disturbances associated with dehydration induced by fasting for 48 hr. These five commercial fluids (30 ml/kg) were given to bullocks with dehydration induced by fasting for 48 hr. Arterial and venous blood samples were taken before fasting, and at 0, 15, 30, 45, 60, 90, 120, 240, 360 min, and 24 hr after initiation of fluid administration. Fasting for 48 hr induced significant reductions in body weight and relative plasma volume (rPV), of approximately 7.72 and 21.93%, respectively. During the administration period, rPV showed a progressive increase from approximately 88.1% after fasting to 113.0% with no significantly differences between groups. A rapid decrease of rPV when fluid administration has been finished was observed in the 5G and RG groups. The results of the fluid administration trial showed that the 1/2 Ringer's and 2.5% glucose combination solution inhibited the acidification of the blood, produced no change in the electrolyte balance of serum, and induced a proper reabsorption rate of glucose in the renals, and was therefore considered the best choice for the rehydration of adult cattle which have had no appetite for over 2 days. -KEY WORDS: bullock, fasting, intravenous fluid therapy, isotonic fluid.

Immunohistochemistry and flow cytometric analysis were used with monoclonal antibodies to examine the phenotype of neoplastic cells from cattle with sporadic bovine leukosis (three cases of calf form, two cases of thymic form, and three cases of intermediate form). Three cases of calf form and two cases of intermediate form were positive for B cell lineage in immunohistologic examination and in flow cytometric analysis for B-B2+, sIgM+, and major histocompatibility class II+. Two cases of thymic form and one case of intermediate form were CD2+, CD5+, CD6+, and CD8+ in immunohistologic examination and in flow cytometric analysis. The results show that neoplastic cells develop from B and T cell lineages in sporadic bovine leukosis.