Antibody isotype response in adult cattle vaccinated with Brucella abortus S19

In a chronological study of sera collected from eight adult cattle vaccinated with 3 X 10(-10) cfu of Brucella abortus S19, antibody of each of the four major isotypes was measured by indirect enzyme immunoassay (ELISA) and by direct and modified complement fixation tests (CFT). Six of the cattle gave antibody responses to the vaccine strain that commenced between days 5 and 8 for all the isotypes in the ELISA, peaked by 1 to 4 months and then declined to low levels by 10 months. Direct CFT and modified CFT titers were measurable by 7 or 8 days post-vaccination, and peaked by 1 month; direct CFT titers disappeared by 5 months while the modified CFT titers lingered for 10 months. Two animals gave cyclical direct CFT and modified CFT antibody responses, a cyclical IgG1 response, a low IgG2 and an elevated IgA response. The amplitude of the cycles was uniform over three cycles while the wavelength increased with time. A year post-vaccination, B. abortus S19 was isolated twice from milk from one of the animals (no attempt was made to culture B. abortus from the other). Sera from B. abortus naturally infected cattle were analysed for comparison.     

Structure—activity relationships for some organotin molluscicides

Bioassay data are reported for 12 organotin compounds, R₃SnX, against the adult snail, Biomphalaria glabrata, an intermediate host of schistosomiasis. The relationship between the molluscicidal activity and the nature of the R and X groups in the organotin compounds is discussed, as well as the possible mode of toxic action of these compounds.     

Mode of action of thiocyanates and iodides in aminotriazole formulations

Ammonium thiocyanate ( I ) was shown to inhibit the oxidation of aminotriazole (3-amino-1,2,4-triazole) in two free-radical generating systems: (a) riboflavin photo-sensitised oxidation; and (b) oxidation by hydroxyl radicals. Evidence from in-vitro studies is presented to show that I could enhance aminotriazole performance by being preferentially oxidised within the leaf, thereby preventing aminotriazole free-radical formation and subsequent conjugation with amino acids and other compounds. This opens up the possibility of a whole new range of additives which could enhance translocation by inhibiting free-radical reactions. A comparison of possible inhibitors revealed that cyanides, iodides and perhaps bromides may be of use in this respect. In addition to inhibiting free-radical reactions, I and potassium iodide ( II ) were shown to have a considerable effect on the uptake of aminotriazole by bean leaves (Phaseolus vulgaris var. Canadian Wonder). In the absence of additives, uptake of aminotriazole was negligible (1.8%); in the presence of a 1:1 molar ratio of I or II , uptake of aminotriazole was increased to 36.6% and 54.2% respectively. At a 3:1 molar ratio of additive:aminotriazole, the respective figures were 63.5% and 81.0%. II appeared to be the more efficient of the two additives at higher humidity. However, the results and observations indicated that the situation may be reversed under low-humidity conditions.     

Measurement of immunoglobulins in reproductive tract fluids of bulls

Seminal, seminal vesicular, urethral and preputial fluids from bulls of two different age groups were assessed for quantitative differences in immunoglobulins. Selected markers were measured in individual samples to differentiate locally derived immunoglobulins from those present as a result of trauma or secretions from other accessory glands.Immunoglobulin levels in reproductive tract fluids from older bulls (5–6 years) were higher than those of younger bulls (3–4 years) and preputial fluids contained the highest concentration of immunoglobulins of all fluids examined. Similarities existed, however, among all fluids in the relative concentrations of immunoglobulins. IgG was generally in highest concentration, though the predominant subclass varied. A marked predominance of IgG₂ over IgG₁ occurred in preputial fluid samples of older bulls. IgA was in second highest concentration, and levels were often equal to or greater than those in serum. IgM was in low concentration and occasionally undetectable. IgG/IgA ratios did not exceed 5 in most of the reproductive fluids, whereas serum ratios were usually over 100. Proportional contents of albumin and immunoglobulin in reproductive tract fluids by comparison with those in serum indicated that substantial quantities of IgG as well as IgA were synthesized locally or derived by selective transport. Increased numbers of plasma cells in the lamina propria of the preputial and penile mucosa of older bulls were correlated with higher immunoglobulin concentrations in preputial fluid from older bulls, suggesting that differences in local synthesis were responsible.