Immunological Variables (immunological + variable)

Distribution by Scientific Domains

Selected Abstracts

Negative effects of changing temperature on amphibian immunity under field conditions

Summary 1Recent evidence of the important role of emerging diseases in amphibian population declines makes it increasingly important to understand how environmental changes affect amphibian immune systems. 2Temperature-dependent immunity may be particularly important to amphibian disease dynamics, especially in temperate regions. Changes in temperature are expected to cause deviations away from optimal levels of immunity until the immune system can respond. 3To test whether temperature changes cause deviations from optimal immunity under natural conditions, we conducted a seasonal survey of adult Red-Spotted Newts and measured basal levels of several immunological variables. 4We then examined these findings in relation to: (1) the lag hypothesis, which predicts that changes in temperature-dependent immune parameters lag behind short-term temperature changes, and (2) the seasonal acclimation hypothesis, which predicts that immune cell production declines during long-term temperature decreases until amphibians can fully acclimate to winter conditions. 5Our results supported both hypotheses, showing a spring lag effect on lymphocyte levels and an even stronger seasonal acclimation effect on lymphocytes, neutrophils and eosinophils in the autumn. Our findings suggest that temperature variability causes increased susceptibility of amphibians to infection, and they have implications for the emergence of disease and the potential for climate change to exacerbate amphibian decline. [source]

Effect of different levels of mannan-oligosaccharide supplementation on some immunological variables in weaned piglets

I. Nochta
Summary The effect of different doses of mannan-oligosaccharide (MOS) on specific and non-specific immune responses was studied in piglets, weaned at 28 days. A total of 58 piglets were used in six groups. Five groups were fed 0, 1, 2, 4 g MOS product per kg diet or with growth promoting antibiotics and immunized by inactivated Aujeszky's disease virus (AyV) vaccine at week 1 and 3 of the experiment (35 and 49 days). A sixth group, receiving the same non-supplemented diets was not immunized. Blood samples for lymphocyte stimulation (LST) and AyV neutralization (VN) tests were taken from all pigs on the first day of the experiment and at weekly intervals for 5 weeks. At week 8, the immunized piglets were infected orally with transmissible gastroenteritis virus. All piglets were weighed and slaughtered at week 10, digesta from small intestine were collected and tested for the presence of secretory (s)IgA. Feeding MOS supplementation resulted in enhanced specific and non-specific immune responses, however, a regressive dose-response of MOS was observed. Both the specific cellular (LST) and humoral responses (VN) were enhanced after 2 weeks of feeding 1 g/kg MOS and significantly differed from the antibiotic positive control. The same tendency was detected in case of the non-specific LSTs, although these started some weeks later showing significant differences by the fifth week. Higher doses of MOS had no further beneficial effect on systemic immunity. In addition, 1 g/kg MOS supplementation group also showed some advantage in local immune responsiveness. Therefore, based on the studied immune variables, 1 g/kg MOS product is suggested in the diet of weaned piglets. [source]

Disentangling the role of MHC-dependent ,good genes' and ,compatible genes' in mate-choice decisions of three-spined sticklebacks Gasterosteus aculeatus under semi-natural conditions

T. L. Lenz
To investigate and disentangle the role of major histocompatibility complex (MHC)-based ,good genes' and ,compatible genes' in mate choice, three-spined sticklebacks Gasterosteus aculeatus with specific MHC IIB genotypes were allowed to reproduce in an outdoor enclosure system. Here, fish were protected from predators but encountered their natural parasites. Mate choice for an intermediate genetic distance between parental MHC genotypes was observed, which would result in intermediate diversity in the offspring, but no mate choice based on good genes was found under the current semi-natural conditions. Investigation of immunological variables revealed that the less-specific innate immune system was more active in individuals with a genetically more divergent MHC allele repertoire. This suggests the need to compensate for an MHC-diminished T-cell repertoire and potentially explains the observed mate choice for intermediate MHC genetic distance. The present findings support a general pattern of mate choice for intermediate MHC diversity (i.e. compatible genes). In addition, the potentially dynamic role of MHC good genes in mate choice under different parasite pressures is discussed in the light of present and previous results. [source]

Effect of diets containing different levels of highly unsaturated fatty acids on physiological and immune responses in Pacific whiteleg shrimp Litopenaeus vannamei (Boone) exposed to handling stress

Laurence Mercier
Abstract Juveniles fed a diet containing a low or a high level of highly unsaturated fatty acids (HUFA) for 38 days were exposed to handling stress. In a first experiment, stress was applied daily for 30 days, after which the physiological and immunological variables were measured, whereas in a second experiment, stress was applied once and samples were obtained 1 and 24 h after the stressor event. Shrimp that were stressed for 30 days showed significantly lower survival, final weight and feed consumption compared with unstressed shrimp. The concentration of the high-density lipoprotein ,-glucan-binding protein was significantly higher in shrimp fed the high-HUFA diet. The glucose concentration in the haemolymph was significantly higher in long-term stressed shrimp compared to controls. The lactate level in the haemolymph was significantly lower in shrimp fed the high-HUFA diet. Lactate and glucose in the haemolymph increased in the 1-h stressed shrimp, but returned to normal levels in 24-h stressed shrimp. A negative effect of repeated-handling stress applied for 30 days was mainly observed on biological performance, whereas the single-stressor event had a more pronounced effect on shrimp physiological and immune responses measured 1 and 24 h after the stressor. A beneficial role of enrichment with HUFA on tolerance to handling stress was observed on immune response capacity. [source]