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611.
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The composition of peripheral blood leukocyte populations was studied following experimental PCV2-infection in 3-week-old piglets. Four of 10 PCV2-infected piglets developed clinical and pathological symptoms consistent with postweaning multisystemic wasting syndrome (PMWS) between 14 and 21 days post-inoculation (p.i.), and were characterised as PMWS-affected. Only these four PMWS-affected piglets, but neither the non-symptomatic infected nor control animals, developed a clear leukopenia. Kinetic analysis demonstrated a clear loss of both CD21(+) B and CD3(+) T lymphocytes in the PMWS-affected piglets. By CD3/CD4/CD8 triple labelling, the influence of PCV2 infection on all T cell sub-populations was discernible. A loss of CD3(+)CD4(+)CD8(+) memory/activated Th lymphocytes was particularly notable. However, all T lymphocyte sub-populations-CD3(+)CD4(+)CD8(+) memory Th, CD3(+)CD4(+)CD8(-) nai;ve Th, CD3(+)CD4(-)CD8(+) Tc and CD3(+)CD4(-)CD8(-) gammadelta TCR(+) lymphocytes-were susceptible to PCV2 infection-induced lymphopenia. CD3(-)CD4(-)CD8(+) NK cells were also depleted in the PMWS-affected animals, but granulocytes and monocytes were less affected. In conclusion, PCV2 infection induces primarily a lymphopenia, but only in animals which subsequently develop PMWS. The lymphopenia can be identified early p.i., particularly with the B lymphocytes. Memory/activated Th lymphocytes might be affected more than the other T cell sub-populations, but as time progressed a collapse of both T and B cell populations was clear.  相似文献   
613.
Porcine circovirus type 2 (PCV2) nucleic acid and/or antigens are consistently observed in cells of monocytic morphology in lesions of pigs affected by post-weaning multisystemic wasting syndrome (PMWS). In this study, PCV2 antigen was detected in the cytoplasm of monocytes, pulmonary macrophages (PMs) and monocyte-derived macrophages exposed to the virus in vitro, by immunofluorescence analysis (IFA) and the phenotype of these cells confirmed by detection of monocytic cell surface markers using flow cytometry. Viral antigen was not observed in lymphocytic cells. Replication of the virus in PMs was investigated further by comparison to that observed in the continuous pig kidney cell line (PK15A) using quantitative virus titration, quantitative PCR and by the detection of double stranded DNA intermediates of viral replication by Southern blotting analyses. Although increases in viral DNA and levels of infectious virus progeny and the presence of replicative intermediates, indicative of viral replication, were observed in PK15A cells, no such changes were observed in PMs in spite of the fact that infectious virus, viral antigen and viral DNA persisted in the cells for at least the duration of the experiment. These results suggest that in vivo, monocytic cells may not represent the primary target for PCV2 replication.  相似文献   
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Immunostimulation, PCV-2 and PMWS   总被引:7,自引:0,他引:7  
  相似文献   
617.
p-Chlorophenylmethylsulfide (PCPMS) was enzymatically sulfoxidized to p-chlorophenylmethylsulfoxide (PCPMSO) in aerobic cotton, carrot, and tobacco cell suspension cultures. Neither boiled nor freeze-killed cell cultures were competent to sulfoxidize PCPMS to PCPMSO. The sulfone, p-chlorophenylmethylsulfone (PCPMSO2), was not produced in any of the three species. The rates of PCPMS sulfoxidation, were cotton > carrot > tobacco. The apparent Km for carrot cells was 88 μM PCPMS (14 μg/ml), while the apparent Vmax was 7 nmol PCPMSO/mg whole cell protein/hr. These rates of sulfide oxidation are higher than previously reported in intact plants.  相似文献   
618.
A four-month-old male bull terrier with an abnormal hindquarter gait was found to have changes suggesting nutritional secondary hyperparathyroidism, together with unusual large foci of non-ossified material in both femoral necks and similar smaller foci in metaphyses of several long bones. Abnormal cartilage was found in the one femoral neck examined at autopsy six weeks later, with features suggesting impaired vascular remodelling of cartilage due to failure of chondrocyte maturation. Similar clinical and radiographic abnormalities were found in three littermates (one male, two females), but not the dam. The status of six other littermates and the sire is unknown. The femoral neck lesions had healed in two pups re-examined eight months later, but some limb bones remained abnormal in shape. The abnormalities in affected pups suggested osteochondrodysplasia.  相似文献   
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Allan D. Watt   《Crop Protection》1983,2(4):417-429
Cereal aphid control strategies are considered in the light of the irregularity of aphid outbreaks, the expected level of damage, the accuracy and type of forecast, the relevant costs, the range of obtainable yields and the farmer's risk considerations. A method by which these strategies (no control, prophylaxis and forecasting) may be considered is given. This method calculates the break-even conditions between different strategies under the influence of several factors and also calculates the value of the forecasting strategy. Forecasting is the best available strategy under average and above-average yielding conditions. This is the case even when the forecast is inaccurate and especially when the forecasting system is inaccurate only its spray recommendation.  相似文献   
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