Field study of the safety, immunogenicity, and efficacy of an inactivated equine rotavirus vaccine.

OBJECTIVE: To determine safety, immunogenicity, and efficacy of an inactivated equine rotavirus vaccine. DESIGN: Prospective randomized controlled trial. ANIMALS: 316 pregnant Thoroughbred mares during the first year of the study and 311 during the second year. PROCEDURE: During the first year, mares received 3 doses of vaccine or placebo, IM, at 8, 9, and 10 months of gestation. Serum neutralizing antibody titers were measured before vaccination and 1 and 35 days after foaling. Antibody titers were measured in foals 1, 7, 35, 60, 90, and 120 days after birth. During the second year, mares that had been vaccinated the previous year received a single booster dose of vaccine approximately 1 month prior to parturition. Mares that had received the placebo the previous year and mares new to the study received 3 doses of vaccine or placebo. Serum neutralizing antibody titers were measured in samples taken from mares approximately 1 day after foaling and from foals approximately 1 and 60 days after birth. RESULTS: Adverse reactions were not observed. Antibody titers were significantly increased at the time of foaling and 35 days after foaling in vaccinated, compared with control, mares and for 90 days after birth in foals born to vaccinated, compared with foals born to control, mares. Incidence of rotaviral diarrhea was lower in foals born to vaccinated, compared with foals born to control, mares, but the difference was not significant. CLINICAL IMPLICATIONS: Results suggest that the equine rotavirus vaccine is safe and immunogenic and that reasonable efficacy under field conditions can be expected.

Purification, characterization and antimicrobial properties of an antibiotic (wassumycin) from Streptomyces species 215.

A yellow amorphous compound, wassumycin, was isolated from an unidentified strain of Streptomyces. Wassumycin inhibited the growth of several species of human and animal pathogenic bacteria especially Clostridia. Wassumycin also inhibited the growth of HeLa cells, and showed good antitumour activity against experimental mouse tumours such as L1210, P388 leukaemias, and B16 melanoma. On the basis of the chemical and antimicrobial properties, the antibiotic appeared similar to the chromomycins and olivomycins, but its ultraviolet, infrared, and proton magnetic resonance spectra differed from theirs significantly.

Treponemycin, a nitrile antibiotic active against Treponema hyodysenteriae.

Two strains of Streptomyces sp. (isolates 275 and 124) were isolated from soil samples collected from the fields around Lewiston, Idaho. Based on their cellular morphology and physiology, the two isolates were identified as Streptomyces albovinaceous. Both isolates produced an antibiotic when grown in liquid culture medium containing homogenized oats. The antibiotic (treponemycin) was isolated from the culture broth by solvent extraction and purified by silica gel column and preparative thin-layer chromatographies. Treponemycin is a crystalline light-yellow compound with an mp of 93 to 95 degrees C, levorotatory, and soluble in most organic solvents. It is sparingly soluble in water but insoluble in petroleum ether. On the basis of elemental analysis and mass spectral data, the molecular formula of the antibiotic was deduced to be C28H43O6N. The infrared spectrum of the antibiotic indicated the presence of unsaturation, nitrile, lactone, or ester or all three functions, and carbonyl functions in the molecule. A sharp infrared absorption band for nitrile at 2,220 cm-1 and the presence of an unsaturated group indicated that the nitrile function may be attached to an unsaturated carbon atom. The presence of dienenitrile functions was further supported by the UV absorption spectrum of the antibiotic, which gave a UVmax at 257 nm. The proton magnetic resonance spectrum of the antibiotic did not give any peak which could be exchanged with deuterated water, which is an indication of the absence of carboxylic and hydroxyl functions in the molecule. All of the functional groupings indicated by the infrared and UV spectra of the molecule were further confirmed by the 13C-magnetic resonance spectrum of the compound. A brief hydrogenation of the antibiotic yielded a biologically active tetrahydro derivative, whereas extended hydrogenation produced an inactive primary amine. Mild alkaline hydrolysis and subsequent esterification of the antibiotic with diazomethane produced an inactive dimethyl ester. Apparently both the nitrile and the lactone functions are essential for the treponomycin molecule to show antimicrobial activity. The antibiotic showed inhibitory activity against several species of bacteria, especially Treponema hyodysenteriae, the causative agent of swine dysentery. In view of the oral 50% lethal dose of 400 mg/g and its low MIC against four stains of T.hyodysenteriae, the antibiotic may have value as a swine dysentery therapeutic.