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1.
Chicks were vaccinated with an Arkansas strain of infectious bronchitis virus (IBV) vaccine when they were 1 day (Trial 1) or 4 weeks old (Trial 2). Starting at 4 weeks 3 days of age, chicks in both trials were subjected to an assay that measures the immunofunctional response of the gland of Harder (GH), one of the components of the head-associated lymphoid tissue (HALT). The assay involved multiple ocular exposures to killed Brucella abortus antigen, after which tears were collected and titered for antibodies to B. abortus. Following this, select tissues from vaccinated and unvaccinated chicks were collected and examined microscopically for specific lesions. Both functional and structural alterations were detected in the HALT of IBV-vaccinated chicks. Antibody titers to B. abortus in vaccinated chicks were significantly lower (P less than 0.05) than in unvaccinated controls. Structurally, there were elevations (P less than 0.01) in the number of lymphoid cells and follicles found in the mucosal lining of the nasal cavity. This occurred in the vaccinated chicks of both trials. Otherwise, histologic changes were confined to the chicks vaccinated at 4 weeks of age (Trial 2). In that trial, there were elevations in lymphoid-cell and follicle numbers in the eyelid (P less than 0.01) and lacrimal gland (P less than 0.05).  相似文献   

2.
The effect of Harderian adenectomy on the antibody response in chickens   总被引：2，自引：0，他引：2  
Intact chicks and those that had their glands of Harder (GH) removed (GHx) at 1 day of age were studied for their response to optically or intraperitoneally (IP) applied antigens. Following exposure of the chicks to sheep red blood cells (SRBCs), killed Brucella abortus, or bovine serum albumin (BSA), serum and tear samples were collected and assayed for antibodies. Of the two sources of antibodies, the serum generally had higher levels than did the tears. The only exception to this occurred in the intact chicks inoculated by the eye, in which serum and tear levels were equivalent. With SRBCs, no difference could be detected between the two routes of inoculation. However, IP inoculation produced higher levels of antibody in the serum of intact and GHx chicks inoculated with B. abortus or BSA and in the tears of the GHx chicks exposed to B. abortus. Removal of the GH resulted in a consistent decrease in antibody levels in the tears, regardless of the route of exposure. Although this effect was noted with all three antigens, it was more pronounced in the trials using B. abortus and BSA. This finding is discussed in terms of describing the importance of the GH as a source of antibodies to optically applied antigens, and its importance as a route of circulating antibody egress. Furthermore, the feasibility of using the antibody response in tears to a test antigen is discussed as a means of measuring the immune status of a functioning GH.  相似文献   

3.
Twenty chicks, 12 turkey poults and 10 ducklings, all 5 weeks old were infected with 2 × 103.5 chick LD50 IBD virus to determine the course of the virus in the 3 poultry species. Uninfected control birds were kept separately. Two infected and 2 control birds/species were euthanized at time intervals between 3 and 168 hours post infection (pi). Sections of thymus, bursa of Fabricius, spleen, liver, kidney, proventriculus and ceacal tonsil were stained for the detection of IBD virus antigen using immunoperoxidase technique. IBD virus antigen positive cells stained reddish-brown and the amount of such cells in tissue sections were noted and scored. Stained cells were present in all organs examined for up to 168 hours pi in the 3 poultry species except ceacal tonsils of ducks at 72 and 120 hours pi. Antigen score was highest in chickens and least in ducks as reflected by average of total scores/sampling time of 12, 10.8 and 8 in chickens, turkeys and ducks respectively. Total antigen score/sampling time in infected chickens peaked twice; 24/48 and 144 hours pi, whereas such bi-phasic peaks were absent in turkeys and ducks. Range of total antigen score at different sampling times was 7–17.5 in chickens, 10–13 in turkeys and 7–10 in ducks indicative of marked viral replication in chickens. Presence of IBD viral antigen in organs of all 3 poultry species is indicative of infections. The innate ability of turkeys and ducks to prevent appreciable replication of IBD virus after infection requires further investigation.  相似文献   

4.
The effects of somatostatin immunoneutralization on growth rate, growth hormone (GH) secretion and circulating insulin-like growth factor I (IGF-I) concentrations were investigated in chickens through the use of passive and active immunization techniques. Intravenous bolus injection of goat-antisomatostatin stimulated a significant (P less than .05) increase in plasma GH levels for one hour post-injection in four and six week old male broiler chickens. The GH response to an intravenous bolus injection of hGRF44NH2 was similar in the antisomatostatin treated chicks and normal goat serum treated controls. Despite the presence of circulating somatostatin antisera after 28 hours, plasma GH levels were not different between control and antisomatostatin-treated chicks at that time. Continuous administration of somatostatin antisera by Alzet pump over a two-week period resulted in significant (P less than .05) elevations in plasma GH levels at one week post-implantation and in circulating IGF-I concentrations after two weeks of administration. Chicks which developed antibodies against somatostatin following active immunization exhibited a 7.1% increase in growth rate which was associated with a significant decrease in abdominal fat. However, neither GH nor IGF-I concentrations were elevated in the chicks which developed somatostatin antibodies. Thus, the benefits gained from somatostatin immunoneutralization may be exerted through mechanisms other than GH.  相似文献   

5.
Age-related susceptibility patterns of turkeys, broilers, and specific pathogen-free (SPF) White Leghorn chickens to experimentally induced infection with turkey or chicken rotavirus isolates were compared. The following determinants were evaluated: clinical signs, onset and duration of virus production, viral titers, involvement of intestinal villi in the replication of the virus, and the development of antibodies against the virus. Older turkeys and chickens were more susceptible than were their younger counterparts, turkeys were more susceptible than were broiler and White Leghorn chickens (regardless of age), and broiler chickens were slightly more susceptible than were age-matched White Leghorn chickens. Turkeys developed diarrhea, accompanied by high viral titers within 1 day after inoculation with virus. Viral antigen was found in the epithelial cells of the intestinal villi throughout the intestinal tract and some cells of the cecal tonsils. Antibodies could be detected as early as 4 to 5 days after inoculation. These findings were more pronounced in turkeys inoculated at 112 days of age than in birds inoculated at a younger age. Age-related susceptibility patterns were similar in White Leghorn and broiler chickens. Infection was subclinical in birds less than 56 days old, whereas older birds developed soft feces. Egg production in the White Leghorn chickens decreased after being inoculated with virus at 350 days of age.  相似文献   

6.
In this paper we present the results of studies on the infectivity of an isolate of avian pneumovirus (APV) from turkeys to broiler chickens. Two-week-old broiler chicks free of antibodies to APV were exposed either by oculonasal or oral route with a cell cultured APV of turkey origin. Chickens from both APV-inoculated groups exhibited clinical signs that included coughing, sneezing, nasal discharge, and watery eyes during 2-8 days postinoculation. Tissue samples from birds in the APV-inoculated group were positive for APV by polymerase chain reaction (PCR) up to 9 days postinoculation. Samples of blood from both oculonasally and orally infected chickens were positive for APV. Intestinal samples from chickens infected with APV orally were positive for the presence of APV on PCR up to 9 days postinoculation. APV was reisolated from samples taken from chickens in both groups inoculated orally and oculonasally. Sera from birds exposed by the oculonasal or by the oral route showed the presence of APV-specific antibodies.  相似文献   

7.
A series of trials was run in leghorn chicks to examine select conditions affecting the tear antibody response to killed Brucella abortus antigen given by eyedrop administration. Specific conditions examined were concentration of antigen, number of antigen exposures, and interval between antigen exposures. Trials were also run to determine the earliest age at which the assay was functional in both broilers and leghorns. Two types of housing (isolators and battery cages) were examined, as were two levels of placement concentration, or bird density (0.32 and 0.64 ft. [0.03 and 0.06 m2]/chicken). All trials included intraperitoneally inoculated chicks as a comparison; tears as well as serum were assayed for antibodies. Of the various antigen regimens evaluated, two exposures of 20% B. abortus given 3 days apart was found to give a satisfactory antibody response in the tears 1 week later. Furthermore, response to B. abortus was found to be somewhat proportional to age, with the minimum age for a satisfactory response being 3 weeks in leghorns or 4 weeks in broilers. Statistically, there were no differences in antibody responses due to the types of housing or levels of placement used.  相似文献   

8.
The progress and transmission of blackhead disease in chickens was studied in battery cages and floor pens in the absence of vectors. Two-week-old chicks were inoculated intracloacally with Histomonas meleagridis and allowed to commingle with others in floor pens. There was no confirmed transmission of blackhead to other birds in the pen, whether stocked at 10% or 25% with infected birds. A second experiment evaluated the effects of feed restriction of chickens on spread of blackhead within floor pens. Inoculated seeder birds had severe cecal lesions of blackhead at necropsy, regardless of feed restriction. Uninoculated birds did not develop lesions by the time of necropsy at 42 days of age, regardless of whether full-fed or limited by skip-day feeding. Chickens inoculated intracloacally with H. meleagridis and placed in battery cages became infected and had cecal lesions of blackhead, but few liver lesions. Chickens allowed to commingle with the inoculated birds in batteries had no lesions of histomoniasis at necropsy 2 wk postinoculation. Coccidial oocysts from turkeys (Eimeria adenoeides) were inoculated along with H. meleagridis from cultures to test the effects of sporozoite penetration in the ceca on progress of blackhead disease. Histomoniasis was not worsened by the interaction with sporozoites, as shown by unchanged severity of cecal lesions, the number of birds showing liver lesions, or the overall number of positive birds. Overall, blackhead infections showed no inclination to spread from bird to bird under conditions of these studies, in contrast to what has been reported for turkeys. These results suggest that the dynamics of blackhead transmission in chickens differs significantly from that of turkeys, where transmission from bird to bird is rapid and effective in the absence of vectors.  相似文献   

9.
Avian paramyxoviruses (APMV) are divided into nine serotypes. Newcastle disease virus (APMV-1) is the most extensively characterized, while relatively little information is available for the other APMV serotypes. In the present study, we examined the pathogenicity of two divergent strains of APMV-3, Netherlands and Wisconsin, in (i) 9-day-old embryonated chicken eggs, (ii) 1-day-old specific pathogen free (SPF) chicks and turkeys, and (iii) 2-week-old SPF chickens and turkeys. The mean death time in 9-day-old embryonated chicken eggs was 112 h for APMV-3 strain Netherlands and > 168 h for strain Wisconsin. The intracerebral pathogenicity index in 1-day-old chicks for strain Netherlands was 0.39 and for strain Wisconsin was zero. Thus, both strains are lentogenic. Both the strains replicated well in brain tissue when inoculated intracerebrally in 1-day-old SPF chicks, but without causing death. Mild respiratory disease signs were observed in 1-day-old chickens and turkeys when inoculated through oculonasal route with either strain. There were no overt signs of illness in 2-weeks-old chickens and turkeys by either strain, although all the birds seroconverted after infection. The viruses were isolated predominantly from brain, lungs, spleens, trachea, pancreas and kidney. Immunohistochemistry studies also showed the presence of large amount of viral antigens in both epithelial and sub-epithelial lining of respiratory and alimentary tracts. Our result suggests systemic spread of APMV-3 even though the viral fusion glycoprotein does not contain the canonical furin proteases cleavage site. Furthermore, there was little or no disease despite systemic viral spread and abundant viral replication in all the tissues tested.  相似文献   

10.
Nine serologic types of avian paramyxovirus (APMV) have been recognized. Newcastle disease virus (APMV-1) is the most extensively characterized virus, while relatively little information is available for the other APMV serotypes. In the present study, we examined the pathogenicity of two strains of APMV-2, Yucaipa and Bangor, in 9-day-old embryonated chicken eggs, 1-day-old specific-pathogen-free (SPF) chicks, and 4-wk-old SPF chickens and turkeys. The mean death time in 9-day-old embryonated chicken eggs was more than 168 hr for both strains, and their intracerebral pathogenicity index (ICPI) was zero, indicating that these viruses are nonpathogenic in chickens. When inoculated intracerebrally in 1-day-old chicks, neither strain caused disease or replicated detectably in the brain. This suggests that the zero ICPI value of APMV-2 reflects the inability of the virus to grow in neural cells. Groups of twelve 4-wk-old SPF chickens and turkeys were inoculated oculonasally with either strain, and three birds per group were euthanatized on days 2, 4, 6, and 14 postinoculation for analysis. There were no overt clinical signs of illnesses, although all birds seroconverted by day 6. The viruses were isolated predominantly from the respiratory and alimentary tracts. Immunohistochemistry studies also showed the presence of a large amount of viral antigens in epithelial linings of respiratory and alimentary tracts. There also was evidence of systemic spread even though the cleavage site of the viral fusion glycoprotein does not contain the canonical furin protease cleavage site.  相似文献   

11.
Rations containing 25% of either regular rapeseed oil (36% erucic acid), Oro rapeseed oil (1.9% erucic acid), soybean oil or a mixture of lard and corn oil were fed to chickens, ducks and turkeys. The regular rapeseed oil ration caused growth depression, increased feed conversion and anemia in all species. All the ducks and some of the chickens fed the regular rapeseed oil ration died. These dead birds were affected with hydropericardium and ascites. No deaths in the turkeys could be attributed to the regular rapeseed oil ration but some turkeys fed this ration had degenerative foci characterized by infiltrations of histiocytic and giant cells in the myocardium. Severe fatty change in the heart, skeletal muscles, spleen and kidney was found at an early age in all birds fed the regular rapeseed oil ration. Less severe fatty change but no other lesions were found in birds fed the Oro rapeseed oil and soybean oil rations.  相似文献   

12.
The bursa anlage failed to develop in chicken embryos injected with 5 micrograms mibolerone on the 5th day of embryonation. Humoral immune responses in treated birds were studied by challenging them with sheep red blood cells (SRBC) and killed Brucella abortus (B. abortus) at 4, 5, 6 and 7 weeks of age. Control birds responded with IgM and IgG titers to SRBC and B. abortus, whereas mibolerone-treated birds completely failed to respond to B. abortus and their responses to SRBC consisted of only IgM agglutinins. Mibolerone-treated birds lacked natural agglutinins to rabbit red blood cells. The total concentration of plasma IgG, measured by radial immunodiffusion, was diminished whereas the IgM level was not influenced by the mibolerone treatment. Mibolerone-treated birds lacked bursal cell specific antigens in the peripheral blood leucocytes (PBL) but they still had Ig-positive fluorescing cells which were fewer in number than those of controls. Splenomegaly resulting from graft vs. host reactions induced in chick embryos by PBL from mibolerone-treated birds was similar to that in control birds, indicating normal alloreactive T cells. These results suggest that IgM responses observed in mibolerone-treated birds are produced by cells from an extrabursal site, and that mibolerone can be used effectively to chemically bursectomize chickens.  相似文献   

13.
The pathogenesis of five different Newcastle disease virus (NDV) isolates representing all pathotypes was examined in commercial and specific pathogen-free (SPF) turkeys. Experimentally-infected birds were monitored clinically and euthanatized, with subsequent tissue collection, for examination by histopathology, by immunohistochemistry for the presence of NDV nucleoprotein, and by in situ hybridization for the presence of replicating virus. Clinically, the lentogenic pathotype did not cause overt clinical signs in either commercial or SPF turkeys. Mesogenic viruses caused depression in some birds. Turkeys infected with velogenic neurotropic and velogenic viscerotropic isolates showed severe depression, and neurologic signs. Histologic appearances for all strains had many similarities to lesions observed in chickens inoculated with the various isolates; that is, lesions were present predominantly in lymphoid, intestinal, and central nervous tissues. However, in general, disease among turkeys was less severe than in chickens, and turkeys could be considered a subclinical carrier for some of the isolates.  相似文献   

14.
Effects of tannic acid (TA) on the immune response of growing chickens were studied in two experiments. In the first experiment, 25 or 30 g TA/kg diet was added to a control diet; added TA reduced (P less than .05) weight gain, protein efficiency rate and weight of bursa of Fabricius, thymus and spleen. Total IgM and IgG immunoglobulin levels (primary and secondary immune responses) against killed Brucella abortus were reduced in TA-fed chickens. Numbers of total white blood cells and absolute lymphocytes also were reduced. Tannic acid feeding also resulted in the involution of bursal follicles. In second experiment, TA-treated birds were challenged with a live culture of Brucella abortus. The total IgM and IgG levels again were depressed along with lymphoid organ weights of treated birds. Persistence of B. abortus in spleens of TA-treated birds was higher. These data suggest that the administration of tannic acid impairs the immune function of growing chickens in a dose-dependent manner.  相似文献   

15.
T-cell-mediated and humoral immune responses were measured in chickens infected with standard and variant strains of infectious bursal disease virus. One-day-old and 3-week-old chickens were infected with these viruses and then given sheep RBC, killed Brucella abortus strain 19, and Newcastle disease virus. Appropriate serologic tests were used to monitor the primary and secondary responses to the antigens. Lymphoblast transformation assays were performed weekly. The response to the infectious bursal disease virus was determined by virus neutralization tests, microscopic examination of bursas, and bursal to body weight ratios. One-day-old chickens had T-cell-mediated and humoral immune suppression with both strains of virus, compared with controls. The lymphoblast transformation responses indicated that the variant strain was significantly (P less than 0.05) more suppressive than the standard strain. Three-week-old chickens had humoral immune suppression with the standard strain, but not with the variant strain. The lymphoblast transformation response was transiently suppressed at this age by the variant strain only. During the first week of infection, 1-day-old and 3-week-old chickens had lower neutralizing antibody titers to the variant strain than to the standard strain.  相似文献   

16.
Avian pneumovirus (APV) causes a respiratory disease in turkeys. The virus has been associated with morbidity and mortality due to secondary infections. Our objective was to determine if APV caused immunosuppression in the T-cell or B-cell compartments and to study the pathogenesis of the disease in APV maternal antibody-lacking 2-wk-old commercial turkeys. APV was administered by the eyedrop/intranasal route. Observations were made for gross lesions, viral genome, and T-cell mitogenesis and cytokine secretion at 3, 5, 7, 14, and 21 days postinoculation (DPI). During the acute phase of the disease that lasted for about 1 wk, the turkeys exposed to APV showed clinical signs characterized by nasal discharge and sinus swelling. Virus genome was detected by in situ hybridization in cells of turbinates and trachea at 3 and 5 DPI. At 3 and 5 DPI, spleen cells of the birds infected with APV markedly decreased proliferative response to concanavalin A (Con A). Con A and lipopolysaccharide stimulation of spleen cells from virus-exposed turkeys resulted in accumulation of nitric oxide-inducing factors (NOIF) in the culture fluid. NOIF were not detected in culture fluids of Con A-stimulated spleen cells of virus-free turkeys. APV did not compromise the antibody-producing ability of turkeys against several extraneous antigens such as Brucella abortus and tetanus toxoid.  相似文献   

17.
Village chickens are an important livestock for many rural families in Myanmar and other developing countries. Village chickens are kept under free-ranging conditions, with confinement only at night. Therefore, it is likely that some deaths are not observed by farmers. We conducted a longitudinal study from November 2003 until May 2004 to describe temporal patterns of mortality of village chickens in 10 villages in Myanmar. Field veterinarians first identified the numbers of birds in all chicken-owning households in each village. We then selected 307 households randomly with stratification by flock size. Each study household was then visited once monthly at which time questionnaires were completed recording current flock structure and numbers of hatchings, mortalities, sales and birds consumed since the previous visit. In addition, sera were collected from a sample of adult birds and growers. Depending on month and age group of chicken, from 71 to 231 (out of 290-307) households had discrepancies in the counts of birds. For chicks, at least one-quarter of the households had unobserved losses of at least 5 chicks per household (maximum 66 chicks); unobserved losses were less for growers and adult chickens. The median month-specific, village-specific mortality rates per 1000 bird-days at risk (counting missing birds as deaths) ranged from 0.8 to 1.7 for adults, from 0.4 to 4.7 for growers and from 8.0 to 16.5 for chicks. Across all birds, the prevalence of protective titres against Newcastle disease virus was 79% (95% confidence interval 74, 84); higher prevalences of protective titres were associated with reduced mortality rates in the following months.  相似文献   

18.
1. Reducing growth rate is often supposed to allow better skeletal development and improve bone quality. In order to test this assumption, flocks of broiler chickens fed on a diet containing 13.31 MJ ME/kg (H) were compared with flocks in which the growth rate was reduced by feeding birds with a low energy diet (L, 9.62 MJ ME/kg). 2. Bone growth was studied in 2 experiments in order to identify any changes in bone tissue of slow-growing chickens that might explain why they are less predisposed to varus-valgus deformities (3.1% vs 19.9%). 3. In experiment 1, the morphology, composition and histomorphometry of the tibiotarsi were analysed in both groups at 1, 12, 26, 42 and 46 d of age. Tibial variables (weight, volume, length, cortex size and structure, dry content and ash percentage) were always reduced in slow-growing birds except at 42 d of age, when tibial weight and cortex areas were similar in both groups. 4. Every variable was similar in both groups, or even higher in H birds, when chickens were compared at similar body weight, suggesting that the low growth rate did not improve bone quantity or quality of the tibiae. 5. In experiment 2, the composition of the tibiotarsi was compared every 2 days during the first week and twice a week until 36 d of age, in H and L birds. Weight and composition of the tibiotarsi did not differ between groups when compared at equal body weight, as also shown in experiment 1. 6. The reduced occurrence of varus-valgus deformities in slow-growing chicks cannot be related to an improvement in the structure and the composition of their bone tissue.  相似文献   

19.
Ismail MM  Tang AY  Saif YM 《Avian diseases》2003,47(3):515-522
We designed this study to compare the replication potential of turkey coronavirus (TCV) and its effect in chickens and turkeys and to study the effect of singleand combined infection of turkey poults with TCV and astrovirus. We studied the pathogenicity of TCV in experimentally inoculated turkey poults and chickens by observing the dinical signs and gross lesions. Two trials were conducted with 1-day-old and 4-wk-old specific-pathogen-free turkey poults and chickens. One-day-old turkey poults developed diarrhea at 48 hr postinoculation. Poults euthanatized at 3, 5, and 7 days postinoculation had flaccid, pale, and thin-walled intestines with watery contents. The 4-wk-old turkeys had no clinical signs or gross lesions. One-day-old and 4-wk-old chicks developed no clinical signs or gross lesions although the TCV was detected in gut contents of the birds throughout the experimental period (14 days). In another experiment, mean plasma D-xylose concentrations in 3-day-old turkey poults inoculated with TCV, turkey astrovirus, or a combination of both viruses were significantly lower than in the uninoculated controls.  相似文献   

20.
1. The productive performance of 4 chicken breed groups managed under semi-intensive conditions in Yucatan, Mexico was evaluated. Thirty-six mixed chickens, one week of age of each of the 4 breed groups (Creole, F1 Hubbard x Creole, 7/8 Hubbard x 1/8 Creole and Hubbard) were used. 2. During 1 to 3 weeks of age all birds were fed on a diet containing 210 g/kg crude protein (CP) and 12.95 MJ/kg metabolisable energy (ME). From weeks 4 to 7, they were given a diet with 190 g/kg CP and 12.55 MJ/kg ME. Food consumption and live body weight were recorded weekly. Statistical analysis of the data was performed according to complete randomised design and means comparison using Tukey test was carried out when necessary. 3. Creole chicks had the lightest weights at all ages as compared to their crosses and the Hubbard birds. At 7 weeks of age, Creole chicks were 2.11, 2.44 and 2.90 times lighter than their contemporary F1, 7/8 Hubbard x 1/8 Creole and Hubbard birds, respectively. Hubbard birds were heavier than F1 and 7/8 commercial x 1/8 Creole birds, and the latter group heavier than the F1 birds. Similarly, Creole chicks had the lowest growth rate compared to the other genetic groups. Heterosis for body weight up to 7 weeks of age was 8.2%. 4. Feed consumption was also lower for the Creole chicks at all ages. Food:gain ratio, however, was higher for the Creole chicks at all ages. Food:gain ratios from weeks 2 to 7 were 2.18, 2.65, 3.04 and 4.36 for the Hubbard, 7/8 Hubbard x 1/8 Creole, F1 and Creole birds, respectively. Heterosis for food:gain ratio from 2 to 7 weeks of age was -7.0%. 5. Crossbreeding of Mexican Creole birds with commercial type broilers might improve productive performance.  相似文献   

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