The effect of antibody to caseous lymphadenitis in ewes on the efficacy of vaccination in lambs

The effect of maternal antibody to the toxin of Corynebacterium pseudotuberculosis, produced by caseous lymphadenitis (CLA) in ewes or by vaccinating ewes before lambing, on the efficacy of vaccination against CLA in their lambs was examined. Lambs were allocated to treatments according to either the vaccination history of their dam or level of CLA toxin antibody of their dam. They were vaccinated twice using 2 different inoculation regimes and then artificially infected with CLA organisms. The number of lambs with CLA lesions was assessed at slaughter. In one experiment high levels of CLA toxin antibody activity in ewes were associated with decreased efficacy of CLA vaccination in their lambs, when lambs were vaccinated at 2 and 8 weeks or 8 and 14 weeks of age. In a second experiment the efficacy of lamb vaccination at 8 and 12 weeks, but not at 14 and 18 weeks of age, was decreased. In sheep flocks with a high prevalence of CLA, vaccinating lambs against CLA at less than 10 weeks of age may not produce optimum protection against CLA in lambs. There was no difference in infection rate between lambs from vaccinated and unvaccinated ewes. However, vaccination of lambs at 2 and 8 wks was less effective that vaccination at 8 and 14 weeks, probably due to reduced immunocompetence in young lambs. In sheep flocks where significant numbers of lambs receive their primary vaccination at less than 3 weeks of age vaccination programmes to control CLA in lambs may be less effective.     

Molecular mechanisms influencing efficiency of RNA interference in insects

RNA interference (RNAi) is an endogenous, sequence‐specific gene‐silencing mechanism elicited by small RNA molecules. RNAi is a powerful reverse genetic tool, and is currently being utilized for managing insects and viruses. Widespread implementation of RNAi‐based pest management strategies is currently hindered by inefficient and highly variable results when different insect species, strains, developmental stages, tissues, and genes are targeted. Mechanistic studies have shown that double‐stranded ribonucleases (dsRNases), endosomal entrapment, deficient function of the core machinery, and inadequate immune stimulation contribute to limited RNAi efficiency. However, a comprehensive understanding of the molecular mechanisms limiting RNAi efficiency remains elusive. Recent advances in dsRNA stability in physiological tissues, dsRNA internalization into cells, the composition and function of the core RNAi machinery, as well as small‐interfering RNA/double‐stranded RNA amplification and spreading mechanisms are reviewed to establish a global understanding of the obstacles impeding wider understanding of RNAi mechanisms in insects. © 2018 Society of Chemical Industry     

Cervical Ripening and Parturition in Cows are Driven by a Cascade of Pro-Inflammatory Cytokines

The final stages of cervical ripening and parturition resemble an inflammatory process. Although the role of cytokines in both spontaneous and experimentally induced parturitions has been described in several small laboratory animals and humans, the involvement of pro‐inflammatory and regulatory cytokines in physiologic parturition in cows has not been determined. In this study, the cytokine expression profiles were assessed in bovine cervical tissue at several stages of pregnancy and at parturition. Serial biopsy samples of the cervix were obtained from 10 cows on day 185 and day 275 of pregnancy (which was on average 5.4 days before parturition) and at parturition. Messenger RNA expression levels of interleukin (IL)‐1β, IL‐6, IL‐8, IL‐10 and tumour necrosis factor (TNF)α were determined using real‐time polymerase chain reaction and the number of neutrophils and eosinophils was estimated by Luna and Sirius Red staining. At parturition, IL‐8 expression had increased 430‐fold (p < 0.001) when compared with that of the day 185 of pregnancy, large numbers of neutrophils had invaded the cervix while eosinophils remained scarce, IL‐1β had increased eightfold (p < 0.05) and IL‐6 had not changed significantly. Additionally, IL‐10 was increased by 10‐fold (p < 0.001) and TNFα decreased by 57% (p < 0.05) when compared with that of the day 185 of pregnancy. The large increase in expression of IL‐8, enabling the influx of neutrophils, is indicative of its important role in the final stage of cervical ripening and at parturition. As previous studies have shown that neutrophils excrete matrix metalloproteinases (MMP), this might contribute to softening of the cervix. In contrast, the only slightly increased levels of IL‐1, steady concentrations of IL‐6 and decreased TNFα, the potential consequences of increased IL‐10 expression, indicate that final cervical of cows in ripening at term parturition is an inflammatory process influenced by regulatory cytokines.     

科学构建国家兽医药品公共信息平台促进产业发展

文章探讨了兽医药品信息对政府、企业、消费者以及产业发展的重要意义，国家如何科学地构建行业专业的信息平台，实施兽医药品产业、政务、公共信息数字化网络化，通过信息化建设推进产业发展。