The role of phagocytic cells in enhanced susceptibility of broilers to colibacillosis after Infectious Bronchitis Virus infection

Colibacillosis results from infection with avian pathogenic Escherichia coli bacteria. Healthy broilers are resistant to inhaled E. coli, but previous infection with vaccine or virulent strains of Infectious Bronchitis Virus (IBV) predisposes birds for severe colibacillosis. We investigated whether IBV affects recruitment and function of phagocytic cells and examined NO production, phagocytic and bactericidal activity, and kinetics of peripheral blood mononuclear cells (PBMC) and splenocytes. Moreover, we measured cytokine mRNA expression in lung and spleen samples. Broilers were inoculated with IBV H120 vaccine or virulent M41 and challenged 5 days later with E. coli 506. A PBS control and E. coli group without previous virus inoculation were also included. Birds were sacrificed at various time points after inoculation (h/dpi). Inoculation with IBV induced extended and more severe colibacillosis than with E. coli alone. At 4dpi, the number of KUL-01(+) PBMC in all E. coli-inoculated groups was significantly higher than in PBS-inoculated birds, which correlated with lesion scores. From 1 to 4dpi, NO production by PBMC from all E. coli-inoculated animals was elevated compared to PBS birds. Bactericidal activity of PBMC in IBV-inoculated animals at 7dpi was lower than in PBS- and E. coli-inoculated birds, but phagocytic capacity and recruitment were not severely impaired. In spleen samples of IBV-infected animals reduced expression of IL-1beta, IL-6, IL-8, IL-10, IL-18 and IFN-gamma mRNA was found 1dpi. Our results suggest that enhanced colibacillosis after IBV infection or vaccination is caused at least by altered innate immunity and less by impairment of phagocytic cell function.     

Immune response of AA broilers to IBV H120 vaccine and sodium new houttuyfonate

In this report, 120 healthy one-day-old AA broilers were divided into six groups. Groups 1–4 received 100, 200, 400 and 800 mg/L of sodium new houttuyfonate (SNH) with IB vaccine H120 respectively. Group 5 received PBS and H120 and group 6 IL-2 and H120. The chickens were inoculated at 7 and 14 days of age. On 0, 7, 14, 21, 28 and 35 post first vaccination, the dynamic changes of peripheral lymphocyte proliferation, cytokine assays and serum antibody titers were assayed respectively by MTT method, ELISA and hemagglutination inhibition assay (HI). The results showed that sodium new houttuyfonate significantly raised IB antibody titer in the chickens and also markedly promoted lymphocyte proliferation. The serum levels of IFN-γ and IL-4 in groups 1–4 were higher than those in groups 5 and 6. Hence, the immunologic enhancement of SNH was slightly superior to that of IL-2 adjuvant. Following challenge with IBV, chickens inoculated with SNH showed fewer and less severe clinical signs, lower death rate and less kidney pathology, as compared to those of the control groups. It indicated that SNH could enhance immune responses and increase protection against virulent IBV challenge in chickens.     

Immune response of AA broilers to IBV H120 vaccine and sodium new houttuyfonate

In this report, 120 healthy one-day-old AA broilers were divided into six groups. Groups 1–4 received 100, 200, 400 and 800 mg/L of sodium new houttuyfonate (SNH) with IB vaccine H120 respectively. Group 5 received PBS and H120 and group 6 IL-2 and H120. The chickens were inoculated at 7 and 14 days of age. On 0, 7, 14, 21, 28 and 35 post first vaccination, the dynamic changes of peripheral lymphocyte proliferation, cytokine assays and serum antibody titers were assayed respectively by MTT method, ELISA and hemagglutination inhibition assay (HI). The results showed that sodium new houttuyfonate significantly raised IB antibody titer in the chickens and also markedly promoted lymphocyte proliferation. The serum levels of IFN-γ and IL-4 in groups 1–4 were higher than those in groups 5 and 6. Hence, the immunologic enhancement of SNH was slightly superior to that of IL-2 adjuvant. Following challenge with IBV, chickens inoculated with SNH showed fewer and less severe clinical signs, lower death rate and less kidney pathology, as compared to those of the control groups. It indicated that SNH could enhance immune responses and increase protection against virulent IBV challenge in chickens.     

Course of infection and immune responses in the respiratory tract of IBV infected broilers after superinfection with E. coli

Colibacillosis results from infection with avian pathogenic Escherichia coli bacteria. Healthy broilers are resistant to inhaled E. coli, but previous infection with vaccine or virulent strains of Infectious Bronchitis Virus (IBV) predisposes birds for severe colibacillosis. The aim of this study was to investigate how IBV affects the course of events upon infection with E. coli. Broilers were inoculated with IBV H120 vaccine virus or virulent M41 and challenged 5 days later with E. coli 506. A PBS and E. coli group without previous virus inoculation were included. Sections of trachea, lung and airsacs were stained for CD4, CD8, gammadelta-TCR, alphabeta1-TCR, and for macrophages (KUL-01) and both pathogens. Changes in the mucociliary barrier of trachea, lung and airsacs did not predispose for bacterial superinfection. The disease in the lungs of the E. coli group and both IBV/E. coli groups was similar. Lesions in the airsacs were more pronounced and of longer duration in the IBV/E. coli groups. The immunocytological changes differed substantially between the E. coli group and both IBV/E. coli groups. In trachea, lungs and airsacs the CD4+ and CD8+ populations were significantly larger than in the E. coli and PBS groups. In the lungs and the airsacs the macrophages were more numerous in the IBV/E. coli and the E. coli groups than in the PBS group. The presence of high numbers of T cells and macrophages in IBV infected birds most likely induced an altered immune response, which is responsible for the enhanced clinical signs of colibacillosis.     

Effect of maternal vaccination on the susceptibility of growing pigs to leptospiral infection

Serum samples were collected from 30 piglets, derived from 17 litters, whose dams had been vaccinated against leptospirosis. Microscopic agglutination test (MAT) titres against Leptospira interrogans serovar pomona varied greatly from pig to pig; there was less variation among littermates. Titres declined between 4 and 10 weeks of age, with an uncorrected half-life of 15.5 days, consistent with IgG being the main antibody class involved. Twelve pigs, 4 derived from unvaccinated sows and 8 from sows vaccinated against leptospirosis, were challenged intravenously at 8 weeks of age with leptospires of serovar pomona. Colostrum-derived antibody protected 4 out of 8 pigs, and in 1 of the remaining 4 the serological response was reduced. Three of the protected pigs showed reduced serological responses and in the fourth the response was strong, but delayed. All of the pigs derived from unvaccinated sows developed leptospiraemia and leptospiruria and showed strong serological responses. Protection by colostrum-derived antibody bore an inexact relationship to MAT titre, but a titre of 16 appeared to be sufficient for protection.     

Influence of vaccination with avirulent herpesvirus on subsequent infection of chickens with virulent Marek's disease herpesvirus.

Vaccination of chickens with turkey herpesvirus (HVT) or attenuated Marek's disease herpesvirus (aMDHV) blocked infection with virulent MDHV (VMDHV) for approximately 5 weeks after contact exposure. However, there was no apparent blockage of infection when challenge virus was administered intraabdominally (IA). Evidence for infection with VMDHV was based on viral isolation by in vivo assay or by detecting precipitins to "A" antigen associated with virulent virus. The HVT stimulated production of neutralizing antibody against VMDHV in a high percentage of chickens, whereas the aMDHV was a comparatively poor inducer of such antibody. Despite this difference, both of the vaccinal viruses conferred protection against development of Marek's disease.     

Effect of dietary supplementation with oregano essential oil on performance of broilers after experimental infection with Eimeria tenella.

A study was carried out to examine the effect of dietary supplementation of oregano essential oil on performance of broiler chickens experimentally infected with Eimeria tenella at 14 days of age. A total of 120 day-old Cobb-500 chicks separated into 4 equal groups with three replicates each, were used in this study. Two groups, one infected with 5 x 10(4) sporulated oocysts of E. tenella and the other not, were given a basal diet and served as controls. The other two groups also infected with E. tenella were administered diets supplemented with oregano essential oil at a level of 300 mg/kg, or with the anticoccidial lasalocid at 75 mg/kg. Following this infection, survival rate, bloody diarrhoea and oocysts excretion as well as lesion score were determined. Throughout the experimental period of 42 days, body weight gain and feed intake were recorded weekly, and feed conversion ratios were calculated. Two weeks after the infection with E. tenella supplementation with dietary oregano oil resulted in body weight gains and feed conversion ratios not differing from the non-infected group, but higher than those of the infected control group and lower than those of the lasalocid group. These parameters correspond with the extent of bloody diarrhoea, survival rate, lesion score and oocyst numbers and indicated that oregano essential oil exerted an anticoccidial effect against E. tenella, which was, however, lower than that exhibited by lasalocid.     

Transmissibility of infectious bronchitis virus H120 vaccine strain among broilers under experimental conditions

The aim of this study was to quantify transmission of infectious bronchitis virus (IBV) H120 vaccine strain among broilers, and to assess whether birds that have been exposed to vaccine strain-shedding birds were protected against clinical signs after infection with a virulent strain of the same serotype. A transmission experiment and a replicate were carried out, each with six groups of commercial broilers. At day of hatch (n = 30) or at 15 days of age (n = 20), half of each group was inoculated with either IBV H120 vaccine (H120 group), virulent IBV M41 (M41 group), or were mock-infected, thereby contact-exposing the other half of each group. Nasal discharge was recorded, and antibody response and virus shedding were measured. To measure clinical protection, four weeks after inoculation all birds, in all groups, were challenged with IBV M41. The reproduction ratio (R; the average number of contact infections caused by one infectious bird) was determined to quantify virus transmission. All contact-exposed birds, except for one in an H120 group, became infected with either IBV H120 or IBV M41. Almost all birds contact-infected with IBV H120 or IBV M41 were subsequently protected against clinical signs after challenge with IBV M41. The lower limits of the 95% confidence interval (CI) of the R of IBV H120 vaccine, and of IBV M41, were significantly <1. For both IBV H120 and IBV M41, the 95% CI was [2.1-infinity] following inoculation at day of hatch and [1.8-infinity] after inoculation at 15 days of age. This finding demonstrates that IBV H120 vaccine is able to spread extensively among broilers. This implies that this vaccine strain might be able to become endemically present in the poultry population. It also implies that, even if not all birds received vaccine during spray application, due to the ability of the vaccine to spread in the flock, they will most likely be protected against clinical signs after a subsequent field virus infection.     

Effect of vaccination on experimental infection with Bordetella bronchiseptica in dogs

OBJECTIVE: To determine comparative efficacy of vaccines administered IM and intranasally, used alone or sequentially, to protect puppies from infection with Bordetella bronchiseptica and determine whether systemic or mucosal antibody response correlated with protection. DESIGN: Randomized controlled trial. ANIMALS: 50 specific-pathogen-free Beagle puppies. PROCEDURE: In 2 replicates of 25 dogs each, 14-week-old puppies that were vaccinated against canine distemper virus and parvovirus were vaccinated against B bronchiseptica via intranasal, IM, intranasal-IM, or IM-intranasal administration or were unvaccinated controls. Puppies were challenge exposed via aerosol administration of B bronchiseptica 2 weeks after final vaccination. Clinical variables and systemic and mucosal antibody responses were monitored for 10 days after challenge exposure. Puppies in replicate 1 were necropsied for histologic and immunohistochemical studies. RESULTS: Control puppies that were seronegative before challenge exposure developed paroxysmal coughing, signs of depression, anorexia, and fever. Vaccinated puppies (either vaccine) that were seronegative before challenge exposure had fewer clinical signs. Puppies that received both vaccines had the least severe clinical signs and fewest lesions in the respiratory tract. Vaccinated dogs had significantly higher concentrations of B bronchiseptica-reactive antibodies in serum saliva before and after challenge. Antibody concentrations were negatively correlated with bacterial growth in nasal cavity and pharyngeal samples after challenge exposure. CONCLUSIONS AND CLINICAL RELEVANCE: Parenterally and intranasally administered vaccines containing B bronchiseptica may provide substantial protection from clinical signs of respiratory tract disease associated with infection by this bacterium. Administration of both types of vaccines in sequence afforded the greatest degree of protection against disease.     

Effect of vaccination on cell populations in lung washes from calves after infection with respiratory syncytial virus

The inflammatory response in the air-passages of the lungs of calves after intranasal inoculation with respiratory syncytial virus (RSV) was compared in RSV-vaccinated and control animals. Total cells recovered from lung washings remained the same; however, the fold by eight days after infection and the type of cells changed from a predominance (85 per cent) of macrophages to equal proportions of macrophages and neutrophils (45 per cent) during the course of infection. The absolute numbers of neutrophils rose by 15-fold. In contrast, when RSV-vaccinated calves were challenged, the total number of cells recovered from lung washings remained the same; however, the numbers of macrophages decreased and the numbers of neutrophils increased by fivefold. Cytological studies of the lung washings revealed no evidence of an exacerbated inflammatory response in RSV-vaccinated calves. Levels of virus replication were significantly reduced in RSV-vaccinated compared with control animals.     

Experimental infection of budgerigars (Melopsittacus undulatus) with a low virulent K21 strain of Toxoplasma gondii

In total 53 budgerigars (Melopsittacus undulatus) were divided into six groups and orally infected with a suspension of oocysts of low virulent Toxoplasma gondii K21 strain in the doses of 10(2), 10(3), 10(4), 10(5) and 10(6), respectively. Blood was collected from the birds prior to the inoculation and then on days 10, 20 and 30 post infection. Latex-agglutination test (LAT) was used for the detection of antibodies in the inoculated birds. The infected birds showed no apparent signs of disease. The antibodies were found in all but two birds inoculated a dose of 10(2) oocysts. Haematological values remained unchanged after infection. T. gondii was isolated by bioassay in mice from all 37 birds fed 10(3) or more oocysts and 6 of 9 fed 10(2) oocysts. The results demonstrate that budgerigars are resistant to T. gondii infection.     

中药“双炎散”对人工感染传支病毒后鸡某些生化指标的影响

10 0只 2 0日龄罗曼鸡随机分成 5组 ,健康对照组不攻毒并隔离饲养 ,其余 4组接种传支病毒。在攻毒组中 ,阳性对照组不给药 ,治疗组在出现症状后按每千克体重 2g饮用“双炎散” ,2个预防组在攻毒前 3天分别按每千克体重 1g和 0 5g开始给药。攻毒后 7天采血检测其有关生化指标。以求证中药“双炎散”颗粒剂的临床疗效。结果表明 :阳性对照组中AST、ALT、CRE显著高于各预防组和治疗组 ;T BIL、HBDH、GGT显著高于健康组且极显著高于各预防组和治疗组。表明“双炎散”颗粒剂对肝功能有较显著的保护功能。BUN、UA极显著、CRE显著高于其他组 ,表明“双炎散”颗粒剂对肾功能有较显著的保护功能。免疫球蛋白IgG、IgA、IgM和GLU较阳性对照组增高。另外 ,各预防组和治疗组钙 (Ca)水平比阳性对照组均有显著的提高。从结果看出 ,2g治疗组和 1g预防组与健康组差异不显著     

不同菌株芽孢杆菌对肉鸡生产性能的影响

<正>益生菌作为一种无毒、无污染、无抗药性、无副作用、无残留的多功能添加剂产品日益为人们所重视。芽孢杆菌由于稳定性好、抗逆性强、复活率高、代谢旺盛等优点,成为目前在畜禽日粮中应用最为广泛的一种益生菌(Salminen等,1998)。     

Protective effects of recombinant Brucella abortus Omp28 against infection with a virulent strain of Brucella abortus 544 in mice

The outer membrane proteins (OMPs) of Brucella (B.) abortus have been extensively studied, but their immunogenicity and protective ability against B. abortus infection are still unclear. In the present study, B. abortus Omp28, a group 3 antigen, was amplified by PCR and cloned into a maltose fusion protein expression system. Recombinant Omp28 (rOmp28) was expressed in Escherichia coli and was then purified. Immunogenicity of rOmp28 was confirmed by Western blot analysis with Brucella-positive mouse serum. Furthermore, humoral- or cell-mediated immune responses measured by the production of IgG1 or IgG2a in rOmp28-immunized mice and the ability of rOmp28 immunization to protect against B. abortus infection were evaluated in a mouse model. In the immunogenicity analysis, the mean titers of IgG1 and IgG2a produced by rOmp28-immunized mice were 20-fold higher than those of PBS-treated mice throughout the entire experimental period. Furthermore, spleen proliferation and bacterial burden in the spleen of rOmp28-immunized mice were approximately 1.5-fold lower than those of PBS-treated mice when challenged with virulent B. abortus. These findings suggest that rOmp28 from B. abortus is a good candidate for manufacturing an effective subunit vaccine against B. abortus infection in animals.     

Antibodies in calves on feed supplemented with chlortetracycline after vaccination with Brucella abortus strain 19

Twenty dairy heifers each consumed 350 mg of chlortetracycline/day in their feed. Four tests were performed on serum specimens from these and 20 control calves after vaccination with Brucella abortus strain 19. The numbers of positive test results on the card test and mean titers on the tube and rivanol agglutination and complement-fixation tests were compared in the 2 groups. Using the rivanol and complement-fixation tests, there were differences in the mean titers at weeks 5 and 6 after vaccination, but by week 10, differences were not found. The results suggest that addition of low concentration of chlortetracycline in feeds have minimal effects on postvaccinal serologic reactions determined after strain-19 inoculation.     

仔猪黄白痢和断奶后腹泻病的疫苗预防效果观察

仔猪黄白痢和断奶后腹泻病在全国各地猪场均有不同程度的发生。虽然经过不断的治疗 ,能把死亡率控制在较低水平 ,但所造成的生长发育缓慢和大量的药物开支对养猪业的发展有着相当大的影响。为解决这个问题 ,不少科研单位研制出了各种疫苗进行预防 ,但其预防效果参差不齐。我场选用浙江农业大学动物科学学院研制的大肠杆菌四价苗和仔猪腹泻水肿病疫苗进行实际预防效果试验 ,取得了较满意的效果。报道如下。1　材料与方法1 .1　试验猪　杭州富阳邦达养殖有限公司下属畜禽水产实验场 1 999年 8月提供的产期相同或相近的经产母猪。1 .2　疫苗　…     

单诺沙星对人工诱发鸡大肠肝菌病的药效试验

根据试管 2倍稀释法测定的单诺沙星及氯霉素对鸡大肠杆菌的最小抑菌浓度 ,对实验性大肠杆菌病鸡进行内服给药 (每隔 12h给药 1次 ,连续 3d)治疗试验。结果表明 ,单诺沙星及氯霉素对鸡大肠杆菌的最小抑菌浓度分别是 0 0 5及 1 6mg/L。单诺沙星以 5mg/kg、氯霉素以40mg/kg的剂量给鸡内服后 ,对大肠杆菌病的治愈率分别为 87 5%及 55 0 %。