Proventriculitis in broiler chickens: effects of immunosuppression

Proventriculitis in broilers causes carcass condemnation when swollen proventriculi tear during evisceration. The cause of this proventriculitis is unknown, but several infectious agents have been associated with it. One such agent, infectious bursal disease virus (IBDV), has been implicated as a cause of proventriculitis, but a direct effect of this virus on the proventriculus has not been proven. The role of IBDV in proventriculitis may be indirect as a result of its ability to cause immunosuppression. The objective of this study was to understand how immunosuppression affects the incidence of proventriculitis in broiler chickens. Immunosuppression was induced in commercial and specific-pathogen-free broiler chickens using chemicals (cyclophosphamide and cyclosporin) or virus (IBDV). All groups were then exposed to a proventricular homogenate produced from diseased birds. At 7 and 14 days postinoculation, the incidence of proventriculitis in these groups was compared to that produced by homogenate exposure in immunocompetent broilers. All birds exposed to the proventricular homogenate from diseased birds developed proventriculitis. Cyclophosphamide and IBDV, both B cell suppressors, did not significantly affect the incidence or characteristics of the proventriculitis observed, although they did have an effect on the size of the proventriculus at 7 days postinoculation. Chickens immunosuppressed with cyclosporin, a T cell suppressor, developed more severe lesions and had a higher incidence of proventriculitis. These findings indicate that both B and T cells are involved in the immune response against proventriculitis, but cell-mediated immunity appears to have a more important role in controlling the disease. IBDV affects both humoral and cellular immunity in the chicken, so although under experimental conditions it didn't have a major effect on proventriculitis, it may explain why control of IBDV in the field seems to reduce the incidence of proventriculitis.     

Pathogenicity by parenteral injection of fowl adenovirus isolated from gizzard erosion and resistance to reinfection in adenoviral gizzard erosion in chickens

The pathogenicity of a serotype-1 fowl adenovirus (FAV-99ZH), which causes adenoviral gizzard erosion by oral inoculation in chickens, was investigated in specific pathogen-free white leghorn chickens. In trial 1, 14 chickens were inoculated intravenously with the virus at 21 days of age and euthanatized for necropsy within 1-14 days of inoculation. Gizzard erosion was grossly observed from day 7 postinoculation (PI), and histologically, FAV-99ZH antigen-positive, basophilic intranuclear inclusion bodies were seen in the gizzard lesions from day 7 to 11 PI. Necrotizing pancreatitis, and cholecystitis and cholangitis associated with the inclusions were observed from day 3 to 14 PI (pancreatitis) and from day 5 to 9 PI (cholecystitis and cholangitis), respectively. The inclusions were also observed in the epithelial cells of the cecal tonsils from day 3 to 5 PI. The virus was recovered from samples of the lesions. It was revealed that FAV-99ZH causes not only gizzard erosion but also pancreatitis, cholecystitis, and cholangitis by intravenous inoculation in chickens. In trial 2, 10 chickens were inoculated orally with the virus twice, at 13 and 36 days of age, and euthanatized for necropsy within 4-17 days after reinfection. Macroscopically, focal gizzard lesions were observed; however, neither necrosis nor inclusions were observed by microscopy. Moreover, FAV was not recovered from the gizzard or rectum of any of the chickens at necropsy. This suggests that the gizzard lesions occurred as a result of the primary infection, and that the chickens were able to resist reinfection.     

Experimental infection of specific-pathogen-free chickens with serotype-1 fowl adenovirus isolated from a broiler chicken with gizzard erosions

Gizzard lesions were formed in specific-pathogen-free (SPF) white leghorn chickens inoculated with fowl adenovirus (FAV). The virus, serotype 1 FAV 99ZH strain (FAV-99ZH), was originally isolated from the gizzard mucosa of commercial broiler chickens exhibiting gizzard erosion with intranuclear inclusion bodies. Five-day-old and 53-day-old SPF white leghorn chickens were inoculated with FAV-99ZH by both oral and ocular routes and then examined at necropsy on days 3, 5, 7, 10, 14, and 21 postinoculation (PI). There were no clinical signs in any of the chickens after the inoculation. Focal gizzard lesions occurred macroscopically, however, in inoculated chickens at several experimental periods. FAV was recovered from tissue samples of the proventriculus, gizzard, pancreas, and rectum by day 10 or 7 PI but was not recovered from liver samples of any of the chickens. These results indicate that FAV isolated from gizzard erosion is able to reproduce gizzard lesions as necrosis and erosion in SPF white leghorn chickens and that it may have a greater degree of tissue tropism in gizzards and other digestive organs than in the liver.     

Megabacteria-associated proventriculitis in poultry in the state of Brandenburg, Germany]

During the second half of the year 2000, we have diagnosed a megabacterial-associated proventriculitis in 13 laying hens and 4 cocks from 14 different flocks and one turkey. All birds were submitted for necropsy because of progressive runting, increased mortality and poor laying performance in the herds. Routine diagnostic workup included necropsy, histology, bacteriology, parasitology and virology. At necropsy, the proventricular of the birds were enlarged. The walls were thickened and the mucosa covered with cloudy, grey-white mucus. Petechial haemorrhages and ulcerations predominantly at the proventricular-ventricular junction and sloughing of the necrotic koilin layer of the ventriculus were inconsistently present. Megabacteria (approximately 40-50 by 2-4 microns, gram-positive to gram-labile, rod-shaped organisms) were present in large numbers in touch preparations of the proventricular mucosal surface. In some of the preparations, the megabacteria showed a branching pattern similar to fungal hyphae. By histopathology, all birds showed moderate to marked, diffuse lympho-plasmacytic proventriculitis. Heterophilic exudation was present in the terminal portion of the proventriculus, where the greatest numbers of the organism were found. Megabacteria were present in the mucus covering the mucosal surface and the lumina of the superficial proventricular crypts, occasionally invading the luminal epithelium. Megabacterial infection was in general associated with other diseases such as avian tuberculosis, salmonellosis, coccidiosis, chlamydiosis and various other bacterial and parasitic infections. Only in one hen no other concurrent infectious organism was detected. The turkey had histomoniasis. Wild birds were regarded as probable source of infection, since all affected birds were kept under conditions allowing contact to wild birds and we have diagnosed megabacterial infections in wild-living green finches earlier.     

The influence of indigestible protein on broiler digestive tract morphology and caecal protein fermentation metabolites

Indigestible dietary protein fermentation products have been suggested to negatively influence broiler performance due to their impact on health and digestive tract morphology. This study evaluated the digestive tract morphology and caecal protein fermentation metabolites of broiler fed 3 dietary protein levels (24%, 26% and 28%) with low or high indigestible protein (LIP, HIP). Two completely randomized 3 × 2 factorial trials were conducted with protein level (PL) and indigestible protein (IDP) as the main factors. In both trials, birds received six diets (24-LIP, 24-HIP, 26-LIP, 26-HIP, 28-LIP and 28 HIP) formulated with no medication. On day 5, trial 1 birds were vaccinated with Coccivac-B52, while trial 2 received no vaccine. Tissue and caecal samples were collected and caecal contents analysed for fermentation metabolites. Differences were considered significant when p ≤ .05. The LIP treatment caecal content in trial 1 at 14 days had greater histamine, agmatine and cadaverine levels, while HIP diets resulted in increased serotonin, tryptamine and spermidine. Histamine, serotonin and tryptamine at day 28 were not affected by IDP, and ammonia was not affected by treatments at day 14 or day 28. At day 14, HIP birds had lower total short-chain fatty acids, higher caecal pH and heavier pancreas, proventriculus, gizzard, jejunum and ileum weights. The same effects of IDP found in trial 1 were observed for histamine, agmatine, cadaverine, serotonin, tryptamine and spermidine at day 21 in trial 2. Trial 2 had a PL-by-IDP interaction influencing tyramine, spermidine (28-LIP > 24-LIP) and spermine with values increasing with PL for LIP diets and remaining constant for HIP diets. An interaction between PL and IDP was found for ammonia level and was similar to interactions for biogenic amines. In conclusion, dietary PL and IDP influence broiler caecal protein fermentation metabolites and those effects varied with coccidiosis vaccination and rearing environment.     

Effects of rice husk diluted dietary switching on the phenotypic change of gastrointestinal tract in adult ganders

1. An experiment was conducted to test the directionality, scaling and reversibility of phenotypic responses of the gastrointestinal tract (GIT) of adult ganders to rice husk (RH) diluted dietary switching. 2. A total of 96 140-d-old ganders were acclimatised to a basal diet for 2 weeks. The birds were randomly assigned to 4 treatments. On d 1, diets in the experimental groups were switched from the basal diet to diets which contained 200, 400 or 600 g/kg RH by mass, with no RH in the basal diet. After 21 d, the diet of all the experimental birds was switched back to the basal diet until d 42. 3. Increasing RH content significantly increased feed intake, and a decreased trend appeared after diet-switching. The weights of geese fed on the 600 g/kg RH diet for 21 d reduced, and were significantly less than those of the other three groups, while body weights (BW) of the geese in all groups increased after diet-switching back to the basal diet. At d 21, significantly heavier relative weights of proventriculus, gizzard and all gut components, except duodenum, were observed in birds fed on a 600 g/kg RH diet, and significantly heavier relative weights of gizzard were observed in birds given a 400 g/kg RH diet. Thickness of the two gastric walls, gizzard length and all gut components lengths increased significantly in birds given a 600 g/kg RH diet compared with the other three groups. At d 42, no significant differences were noted in the relative weights or lengths of GIT, except for the caeca, which were significantly heavier in birds fed on 600 g/kg RH diet. 4. The results of the experiment were in accordance with the predictions of the hypothesis that there is matching between loads and capacities. The observed phenotypic responses were directional and scaled to the demands.     

鸡传染性腺胃炎病毒(暂定名)的致病性

用暂定为鸡传染性腺胃炎病毒（ＩＰＶ）的ＺＪ９７１株，经口服、腹腔、泄殖腔、口服－腹腔－泄殖腔联合不同途径接种于８日龄来航非免疫雏鸡，均可引起雏鸡发病；其中，以口服－腹腔－泄殖腔联合途径感染效果最佳，腹腔途径次之一。感染雏鸡生长阻滞、体重增长缓慢；剖析眼观病变主要以腺胃重量增加，腺胃指数增大，胸腺、法氏囊萎缩为特征；病理组织学变化主要以萎缩性胃炎、法氏囊炎、十二脂肠卡他性炎为特征。     

Effect of reticuloendotheliosis virus on the response of chickens to Salmonella typhimurium infection

Groups of 25 chickens free of maternal antibody to reticuloendotheliosis virus (REV) were inoculated with either third or seventh passage REV at either one or seven days of age. Some of the birds inoculated at day 1 with REV were inoculated with Salmonella typhimurium either concurrently or six or 13 days later while some of those inoculated with REV at day 7 were inoculated concurrently with S typhimurium. At day old, infection with S typhimurium alone caused the death of 12 of 25 chicks whereas in the dual infection, using the third passage REV, 18 of 25 birds died. Similarly no seven or 14 day old chickens died when challenged with S typhimurium alone, but previous day-old infection with REV caused a respective mortality of eight of 25 and five of 25 birds. With the seventh passage REV a similar pattern was seen. At day old S typhimurium infection alone killed seven of 25 birds whereas combined with virus the mortality was 14 of 25 and while S typhimurium alone killed none of 25 chicks infected at seven days old, the mortality in birds also infected with REV was 14 of 25. Combined virus and bacterial infections did not increase the proportion of feathering defects in birds surviving S typhimurium infections. There was a significantly higher proportion of feathering defects in birds infected with third passage virus compared with seventh passage virus. Although a higher proportion of birds had antibody responses to REV in the seventh than in the third passage group, there was no discernible difference in the effect the different viruses had on chickens' susceptibility to S typhimurium.     

Studies on orthoreoviruses isolated from young turkeys. II. Virus distribution in organs and serological response of poults inoculated orally

Day-old specific-antibody-negative turkey poults were inoculated orally with cloned turkey reovirus isolate 81-68. Virus reisolations from 11 different tissues revealed widespread distribution at 3, 5, and 7 days postinoculation (PI). Virus was isolated from the intestines until 21 days PI. Virus was isolated from tendons until day 7 PI and again at day 28 PI. Reovirus serum-neutralization antibodies appeared as early as 7 days PI. All inoculated birds showed positive VN serum titers (greater than or equal to 1:20) by day 21 PI. No reovirus was isolated from control poults, and they remained antibody-negative during the entire experiment.     

Experimental reproduction of transmissible viral proventriculitis by infection of chickens with a novel adenovirus-like virus (isolate R11/3)

Transmissible viral proventriculitis (TVP) was experimentally reproduced in 2-wk-old specific-pathogen-free chickens and commercial broiler chickens by eyedrop inoculation of adenovirus-like virus (AdLV), isolate R1 1/3. No clinical signs and no weight gain depression were observed in chickens inoculated with AdLV (R11/3); however, gross and microscopic lesions characteristic of TVP were present in proventriculi of inoculated chickens. Proventriculi of AdLV (R11/3)-inoculated chickens were markedly enlarged, compared with sham-inoculated controls, by day 7 postinoculation (PI). Microscopic lesions in proventriculi of inoculated chickens were detected beginning on day 3 PI and consisted of degeneration and necrosis of glandular epithelium, ductal epithelial hyperplasia, replacement of glandular epithelium with ductal epithelium, and diffuse interstitial lymphoid infiltration; no microscopic lesions were observed in other tissues. AdLV (R11/3) antigens were detected in proventriculi by immunohistochemistry on days 3-10 PI in inoculated SPF chickens and days 3-21 PI in inoculated commercial broiler chickens; no viral antigens were detected in other tissues. AdLV (R11/3) was reisolated from proventriculi of inoculated SPF and commercial broiler chickens on days 5 and 7 PI. No virus, viral antigens, or lesions were detected in proventriculi collected from sham-inoculated chickens. These findings indicate an etiologic role for AdLV (R11/3) in TVP.     

Pathogenicity of serotype 1 fowl adenovirus in commercial broiler chickens.

The pathogenicity of a serotype 1 fowl adenovirus (FAV-99ZH), isolated from broiler chickens exhibiting gizzard erosion, was investigated in commercial broiler chickens. Five-, 3-, and 1-wk-old commercial broiler chickens were inoculated with FAV-99ZH by both oral and ocular routes. In the 5-wk-old chickens (trial 1), none of which had the maternal antibody to FAV-99ZH, severe gizzard erosions were observed on days 5, 7, and 10 postinoculation (PI). Among the 3-wk-old chickens (trial 2), which were separated into a control group and three treatment groups according to their maternal antibody titer levels, some chickens showed clinical signs such as depression and anorexia. Compared with the control group, all the treatment groups showed decreased weight gain. One treatment group, moreover, showed significantly decreased (P < 0.05) weight gain on day 10 PI. Severe gizzard lesions, such as erosion or ulcers, were observed from day 4 PI in all treatment groups regardless of their maternal antibody levels. The 1-wk-old chickens (trial 3) were separated into a control group and two treatment groups according to their titer levels of the inoculated virus. In spite of high maternal antibody levels, severe gizzard lesions were observed in both treatment groups, which also showed decreased weight gain. One treatment group, inoculated with the higher dose, showed significantly decreased (P < 0.05) weight gain on days 10 and 14 PI compared with the control group. Fowl adenovirus was recovered mainly from gizzard and rectal (including feces) samples from inoculated chickens but was not recovered from liver samples in any of the trials or in any of the control chickens. Although the reproduced disease was similar to that described in a previous report of experimental infection of specific-pathogen-free (SPF) white leghorn chickens with fowl adenovirus, the pathogenicity of FAV-99ZH in commercial broiler chickens was more severe than that in the SPF white leghorn chickens. The results of the present study indicate that FAV-99ZH isolated from gizzard erosion had pathogenicity and produced severe lesions in the gizzards of broiler chickens and that FAV-99ZH could infect and produce illness in broiler chickens with maternal antibodies against this virus.     

Early pathogenesis in chicks of infection with an enterotropic strain of infectious bronchitis virus

One-day-old specific-pathogen-free chicks were inoculated intranasally and intraocularly with infectious bronchitis virus (strain G). At days 1, 3, 5, 7, 10, and 14 postinfection, three birds were euthanatized, and the virus contents of both enteric tissues and some non-enteric tissues were assayed. Immunofluorescence and histopathological studies were also conducted. Six of 30 chicks died of nephritis between days 5-10 postinfection. Gross kidney lesions were the major pathological abnormalities. Inflammation was observed histologically in trachea, kidney, and rectum. High virus titers were found at various times in trachea, kidney, and all enteric tissues except for the jejunum. Relatively high titers of virus were still detectable at day 14 postinfection in the kidney, proventriculus, cecal tonsil, ileum, rectum, and bursa of Fabricius. Immunofluorescence staining showed viral antigens in enterocytes at the tips of villi in the ileum and rectum, and in the bursa. Viral antigens were also demonstrated in the epithelial cells of the trachea and in kidney tubules.     

Immune dysfunction following infection with chicken anemia agent and infectious bursal disease virus. II. Alterations of in vitro lymphoproliferation and in vivo immune responses.

To determine the functional impact of alterations in lymphocyte concentrations and ratios following infection with chicken anemia agent (CAA) alone or in combination with infectious bursal disease virus (IBDV) on the immune system of young chickens, in vitro lymphoproliferation assays and in vivo responses to vaccination with several common viral agents were assessed at various time intervals post-inoculation (PI). Concanavalin A (Con A), phytohemagglutinin (PHA) and pokeweed mitogen (PWM) stimulation of splenic lymphocytes (SPL) collected from control birds could not be detected until 10-14 days PI. Infection with CAA was characterized by significantly higher PWM stimulation of SPL at 17 days PI and significantly lower PWM stimulation of peripheral blood lymphocytes (PBL) at 14 days PI, compared with uninfected controls. Concanavalin A and PWM stimulation of SPL was significantly increased in birds inoculated with IBDV alone. Lymphocytes harvested from birds inoculated simultaneously with CAA and IBDV had significantly lower responses. Effects on humoral and cell-mediated immunity following CAA and/or IBDV were determined by evaluating vaccination responses to Newcastle disease virus (NDV), fowl pox virus (FPV) and infectious laryngotracheitis virus (ILTV) during the acute phase of CAA infection (2 weeks PI). Vaccination of birds 2 weeks following CAA infection at 1 day of age resulted in decreased protection against NDV (85.7%) and ILTV (7.1%) challenge compared with protection rates in control birds (100% and 53.3% respectively). Infectious bursal disease virus infection was associated with decreased protection against NDV (60%) only. Concomitant infection at 1 day of age resulted in a greater reduction in NDV challenge protection (33.3%), slightly decreased FPV protection (87.5%), increased numbers of persistent FPV vaccination lesions and increased protection against ILTV challenge (71.4%). Vaccination of birds 2 weeks following CAA infection at 2 weeks of age resulted in slightly decreased NDV humoral antibody, development of persistent FPV vaccination lesions (17%) and increased immunity to ILTV challenge compared with control birds (83.3% vs. 66.7%). Chickens inoculated with IBDV alone displayed a more severe depression in NDV antibody titers and only a slight decrease in ILTV protection. Vaccination following concomitant infection at 2 weeks of age resulted in a higher percentage of FPV persistent vaccination lesions (39%) and greatly enhanced immunity to ILTV challenge (100%).     

A single vaccination of commercial broilers does not reduce transmission of H5N1 highly pathogenic avian influenza

ABSTRACT: Vaccination of chickens has become routine practice in Asian countries in which H5N1 highly pathogenic avian influenza (HPAI) is endemically present. This mainly applies to layer and breeder flocks, but broilers are usually left unvaccinated. Here we investigate whether vaccination is able to reduce HPAI H5N1 virus transmission among broiler chickens. Four sets of experiments were carried out, each consisting of 22 replicate trials containing a pair of birds. Experiments 1-3 were carried out with four-week-old birds that were unvaccinated, and vaccinated at day 1 or at day 10 of age. Experiment 4 was carried out with unvaccinated day-old broiler chicks. One chicken in each trial was inoculated with H5N1 HPAI virus. One chicken in each trial was inoculated with virus. The course of the infection chain was monitored by serological analysis, and by virus isolation performed on tracheal and cloacal swabs. The analyses were based on a stochastic SEIR model using a Bayesian inferential framework. When inoculation was carried out at the 28th day of life, transmission was efficient in unvaccinated birds, and in birds vaccinated at first or tenth day of life. In these experiments estimates of the latent period (~1.0 day), infectious period (~3.3 days), and transmission rate parameter (~1.4 per day) were similar, as were estimates of the reproduction number (~4) and generation interval (~1.4 day). Transmission was significantly less efficient in unvaccinated chickens when inoculation was carried out on the first day of life. These results show that vaccination of broiler chickens does not reduce transmission, and suggest that this may be due to the interference of maternal immunity.     

Pathogenesis of porcine reproductive and respiratory syndrome virus infection in mid-gestation sows and fetuses.

Two experiments were undertaken to evaluate whether porcine reproductive and respiratory syndrome (PRRS) virus was able to cross the placenta and infect midgestation fetuses following intranasal inoculation of sows and whether PRRS virus directly infected fetuses following in utero inoculation. In experiment 1, eight sows between 45 and 50 days of gestation were intranasally inoculated with PRRS virus (ATCC VR-2332), and four control sows were inoculated with uninfected cell culture lysate. Virus inoculated sows were viremic on postinoculation (PI) days 1, 3, 5, 7 and 9, shed virus in their feces and nasal secretions, and became leukopenic. Sixty-nine of 71 fetuses from principal sows euthanized on PI day 7, 14 or 21 were alive at necropsy and no virus was isolated from any of the fetuses. Two principal sows that farrowed 65 and 67 days PI delivered 25 live piglets and three stillborn fetuses. The PRRS virus was isolated from two live piglets in one litter. In experiment 2, laparotomies were performed on five sows between 40 and 45 days of gestation and fetuses were inoculated in utero with either PRRS virus alone, PRRS virus plus a swine serum containing PRRS antibodies, or uninfected cell culture lysate. Three sows were euthanized on PI day 4 and two sows on PI day 11. Viral replication occurred in fetuses inoculated with virus alone and was enhanced in fetuses inoculated with virus plus antibody. No virus was isolated from control fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)     

鸡传染性支气管炎病毒D971分离株与M41株、T株接种鸡的病理形态学比较研究

鸡传染性支气管炎病毒D971分离株感染SPF鸡后主要表现为消瘦、稀便、伴有轻微的呼吸症状；剖检可见腺胃乳头肿胀、充出血、或乳头凹陷，并附有大量黏液；组织学观察可见腺胃黏膜上皮和固有层有坏死、脱落或溃疡，个别病例见有淋巴样细胞浸润，肌胃黏膜有中度坏死，伴有少量淋巴样细胞浸润，实质器官细胞变性、坏死，脾、胸腺及法氏囊的淋巴细胞有较为明显的坏死。M41株和T株感染SPF鸡后，其腺胃变化不明显。     

Quantity of virulent fowl adenovirus serotype 1 correlates with clinical signs,macroscopical and pathohistological lesions in gizzards following experimental induction of gizzard erosion in broilers

In the present study day-old specific-pathogen-free (SPF) and commercial broilers with maternally derived fowl adenovirus serotype 1 (FAdV-1) antibodies were orally infected with a European “pathogenic” FAdV-1, isolated from broilers showing signs of gizzard erosion. During the experiment, broilers were observed and weighed daily up to 17 days post infection (dpi). Clinically, both infected groups showed significant decrease of weight compared to respective negative control groups. Birds were examined by necropsy at 3, 7, 10, 14 and 17 dpi. Pathological changes in the gizzards were noticed in both experimentally infected groups from 7 dpi onwards. Macroscopically, erosion of the koilin layer and inflammation or ulceration of the gizzard mucosa were observed. Histologically, presence of FAdV-1 in intranuclear inclusion bodies of degenerated glandular epithelial cells was demonstrated by in-situ hybridization and inflammatory cell infiltration of the lamina propria, submucosa and muscle layer was detected. Tissue samples were investigated by a recently developed real-time PCR and the viral DNA load was calculated from gizzard, liver, spleen and cloacal swabs with the highest amounts of FAdV-1 DNA found in the gizzard. For the first time, successful reproduction of clinical signs in broilers as well as pathological lesions in the gizzard were achieved with a European FAdV-1 isolate displaying some genetic differences to so far reported virulent FAdV-1 from Japan. Furthermore, highest viral load in gizzards could be linked with macroscopical and histological lesions. Therefore, the conducted analyses provide important insights into the pathogenesis of adenoviral gizzard erosion.