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110 blood samples from clinically healthy mares of English breed, half-blood and the Wielkopolska race were tested for the presence of EHV-1 and EHV-2 using nested PCR. 15 samples were EHV-1-positive, 24 samples were EHV-2-positive, whereas only 4 samples were both EHV-1 and EHV-2 positive. The virus was isolated from PBLs in equine dermal cell cultures by co-cultivation or by culture inoculation with cell lysates derived from PBLs. A total of 14 strains were isolated from EHV-2 and EHV-1/EHV-2-positive samples. However, all of them were identified by nPCR as being type 2. Since no EHV-1 was isolated, even from dually infected leukocytes, it was concluded that the presence of EHV-2 does not stimulate in-vitro isolation of EHV-1 from infected leukocytes. It is tempting to speculate that such stimulatory effects in-vivo may involve EHV-2-induced immunosupression. Despite any possible mechanism of EHV-1 stimulation, it seems that EHV-2 does not play a significant role in the epidemiology of EHV-1-caused miscarriages in horses since mixed infections are rather rare.
The study evaluated the status of pigs immunological systems during streptococci and mixed infections of the respiratory tract caused by S. suis, Mhp and PPRSV. T lymphocytes, including the proportions of Th and Tc subpopulations, as well as B lymphocytes were examined. Additionally, CD2+ and CD8+ co-expression with the receptor for IL-2 (CD25) was analyzed. Immunodetection was performed using pairs of monoclonal antibodies against CD2 and CD21, CD4 and CD8 as well as CD5 and CD8, with isotype specific polyclonal antibodies conjugated to fluorochromes. Infections caused by S. suis as well as mixed infections of the respiratory tract resulted in an increase in the total blood leukocyte count, noted in the peak of the disease as well as 4 weeks later. However different mechanisms of specific cellular defense were apparent during streptococci and poliethiological respiratory infections in the pigs. An increase in the percentage of Tc lymphocytes and double positive CD4+CD8+ cells without a decrease in the number of B lymphocytes was noted in animals infected with S. suis. An increase in the number of Th and Tc double positive lymphocytes as well as NK cells was observed during infections caused by S. suis, Mhp and PRRSV. Additionally, a significant decrease of CD2+ and CD8+ activated T cells co-expressed with CD25 was observed in this group of animals accompanied by an increase in the population of the above cells without the expression of IL-2R receptor.
Infection of calves with parainfluenza virus (PI₃) and bovine leukemia virus (BLV) induced a clear immunologic response. A high titre of HI type antibodies (1:1280-1:2560) 2 weeks after the injection (p.i.) of PI₃ has been determined. The antibodies persisted at the level of 1:1280-1:2560 for one month and then steadily decreased. The Geometric Mean Titre (GMT) of antibodies for PI₃ virus in this group of calves after 2, 4 and 6 weeks and after 2, 3 and 4 months p.i. was 2250, 1810, 2560, 905, 240 and 323.8, respectively. In calves infected exclusively with PI₃ virus the positive HI titres were 1:80-1:160 two weeks p.i., but the highest titres (1:320-1:1280) were noted at 4 and 6 weeks after infection. Titres 1:20-1:80 were noted at the 4th month after infection. The GMT of antibodies in these calves was 95.1, 678, 1280, 269, 170 and 33.6, respectively. The level of antibodies for calves infected with PI₃ virus and BLV was two- or threefold higher than that in animals infected with PI₃ virus only. The HI titres were 23-fold higher in these animals at 2 weeks p.i. The simultaneous infection of calves with PI₃ virus and BLV significantly enhances immune response and the level of HI type antibodies for PI₃ virus.
The definition of the porcine respiratory disease complex (PRDC) is presented and compared with diseases caused by a single etiological viral or bacterial agent. The classification of viruses or bacteria participating in the multifactorial etiology of disease complexes, among them PRDC, include microorganisms initiating the pathological process, as well as a second group of microorganisms, following after the primary destruction of the resistance to infection, that joins in the pathogenesis of the pathological complex. Another grouping takes into account the higher and lower importance of the etiological agents in causing disease and losses in animal production. The role of the following microorganisms participating in the etiology of PRDC is defined as follows: Porcine reproductive and respiratory syndrome virus, Swine influenza virus, Aujeszky disease virus, Porcine circovirus type 2, Porcine respiratory corona virus, Porcine cytomegalovirus, Mycoplasma hyopneumoniae, Bordetella bronchiseptica, Pasteurella multocida, Haemophilus parasuis, Streptococcus suis, Actinobacillus suis, Arcanobacterium pyogenes and Salmonella spp. Data on simultaneous bacterial-bacterial interactions, viral-viral interactions, and bacterialviral interactions are discussed.
The purpose of this work was to evaluate under experimental conditions the clinical and economic of the combined use of tiamulin and tetracycline in the treatment of mixed infections of the respiratory system. Sixteen piglets, approximately 12 kg, were used in the experiment. The animals were free of Mycoplasma hyopneumoniae (M.hp.), Bordetella bronchiseptica (B.b.), Pasteurella multocida (P.m.) and Actinobacillus pleuropneumoniae (A.pp). The piglets were infected at day „0” with an M.hp. suspension at a dose of 10⁷ cfu/ml. One ml of this suspension was given into each nostril. After 14 days the animals were randomly divided into 2 groups (experimental I and control II) and infected with a suspension of dermonecrotoxic strain of P.m. The density of this culture was 10⁹ cfu/ml. Two ml of this suspension was administered into each nostril. On the same day treatment of the experimental group was started using doses of tiamulin and tetracycline recomended by the producer. After 10 days treatment was finished. Six weeks after the P.m. infection all sows were killed. The efficacy of the therapy was evaluated on the basis of bacteriological and serological examinations and post mortem findings: estimation of lesions in the lungs, isolation of M.hp. and P.m. from lung tissue. The dynamics of body weight gains and feed conversion were also determined. After investigation it was determined that administration of the above mentioned antibiotics eliminated M.hp. and P.m. in all animals from the experimental group. In the control group M.hp. was isolated in 3 cases and P.m. in 5 cases. There were considerable visible differences in the spread of lesions in lungs from treated and untreated sows. Mean body weight at the day of slaughter in the experimental group was about 6.5 kg higher than in the control. There were significant differences in dynamics of body weight gains visible in the whole period between P.m. infection and the day of slaughter. Feed conversion was also about 20% better in the treated group. It was concluded that tiamulin and tetracycline combination was effective in the therapy of experimentally induced, mixed infection of the respiratory system of pigs.
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