Presumed Spontaneous Astrocytoma in a Domestic Backyard Chicken.

A cerebral tumor was identified in an adult female domestic chicken (Gallus domesticus). On gross examination, the cut surface of the cerebrum revealed a poorly circumscribed, pale tan soft mass within the thalamus and midbrain. On histologic examination, there was an unencapsulated, multilobulated neoplasm composed of spindle cells on a loose fibrovascular stroma. Neoplastic cells had variably distinct cell borders, abundant fibrillar eosinophilic cytoplasm, oval nuclei with finely stippled chromatin, and 1-2 distinct nucleoli. There was moderate anisocytosis and anisokaryosis with <1 mitoses per 2.37 mm2. The morphologic features of the neoplastic cells were consistent with an astrocytic neoplasm. PCR was performed on formalin-fixed paraffin-embedded sections of brain tissue, which was negative for subgroup A avian leukosis virus. Based on these findings, the tumor was diagnosed as a presumed spontaneous astrocytoma.

Reporte de caso - Presunto astrocitoma espontáneo en un pollo doméstico de traspatio. Se identificó un tumor cerebral en una gallina doméstica adulta (Gallus domesticus). En el examen macroscópico, la superficie de corte del cerebro reveló una masa blanda de color canela pálido mal delimitada dentro del tálamo y el mesencéfalo. En el examen histológico, había una neoplasia multilobulada no encapsulada compuesta de células fusiformes sobre un estroma fibrovascular laxo. Las células neoplásicas tenían bordes celulares diferenciados de forma variable, abundante citoplasma eosinofílico fibrilar, núcleos ovalados con cromatina finamente punteada y 1 o 2 nucléolos distintos. Había anisocitosis moderada y anisocariosis con <1 mitosis por 2.37 mm2. Las características morfológicas de las células neoplásicas eran compatibles con una neoplasia astrocítica. Se realizó una PCR en secciones de tejido cerebral incluidas en parafina y fijadas con formalina, que resultó negativa para el virus de la leucosis aviar del subgrupo A. Con base en estos hallazgos, el tumor se diagnosticó como un presunto astrocitoma espontáneo.

Hemorrhagic Hepatopathy in Broiler Breeder Pullets: Gross and Microscopic Pathology and Factors Associated with Incidence.

Hemorrhagic hepatopathy is a syndrome reported in layer pullets resulting in mortality and lesions including hepatic, splenic, and intestinal necrosis; hepatic and splenic enlargement; hemorrhages; amyloidosis of the muscle, spleen, and liver; accumulation of noncoagulated hemorrhagic fluid in the coelom; and frequently, granulomatous myositis at bacterin injection sites. The syndrome is characterized in the literature in table egg layer pullets and is thought to be associated with the administration of bacterin vaccines, namely, frequently Salmonella enterica subsp. enterica bacterins. Hemorrhagic hepatopathy is recognized by industry veterinarians as also occurring infrequently in broiler breeder pullets in the United States. As the condition is likely due to an inflammatory process in response to bacterial lipopolysaccharide inoculation, it is important to characterize both the pathologic changes and predisposing factors for the condition in broiler breeds, which are immunologically different from table egg layer breeds. In this study, we characterize the gross and microscopic lesions observed in a series of diagnostic laboratory cases of hemorrhagic hepatopathy in broiler breeder pullets and suggest a possible pathophysiology for the condition. Additionally, we report results from a case survey of the United States broiler industry that suggest that the condition is due to a reaction to bacterin vaccination and that certain bacterin products may predispose pullet flocks to develop the condition. Although further research is indicated, these findings establish hemorrhagic hepatopathy as a pathologic condition of broiler breeder pullets and may aid in the diagnosis and prevention of the syndrome.

Artículo regular­La hepatopatía hemorrágica en pollitas reproductoras pesadas: Patología macroscópica y microscópica y factores asociados con la incidencia La hepatopatía hemorrágica es un síndrome reportado en pollitas ponedoras que resulta en mortalidad y lesiones, incluyendo necrosis hepática, esplénica e intestinal; agrandamiento hepático y esplénico; hemorragias; amiloidosis del músculo, bazo e hígado; acumulación de líquido hemorrágico no coagulado en la cavidad celómica; y con frecuencia, miositis granulomatosa en los lugares de inyección de bacterina. El síndrome se ha caracterizado en la bibliografía en pollitas ponedoras de huevo comercial y se cree que está asociado con la administración de vacunas de bacterianas, con frecuencia bacterinas de Salmonella. Los veterinarios de la industria reconocen que la hepatopatía hemorrágica también ocurre con poca frecuencia en pollitas de reproductoras pesadas en los Estados Unidos. Como es probable que esta condición se deba a un proceso inflamatorio en respuesta a la inoculación de lipopolisacáridos bacterianos, es importante caracterizar tanto los cambios patológicos como los factores predisponentes para la afección en las líneas de pollos de engorde, que son inmunológicamente diferentes de las líneas ponedoras de huevo comercial. En este estudio, se caracterizaron las lesiones macroscópicas y microscópicas observadas en una serie de casos de laboratorio de diagnóstico de hepatopatía hemorrágica en pollitas reproductoras de pollos de engorde y sugerimos una posible fisiopatología de esta condición. Además, se reportan los resultados de una encuesta de casos de la industria de pollos de engorde en los Estados Unidos que sugiere que la condición se debe a una reacción a la vacunación con bacterinas y que ciertos productos de las bacterinas pueden predisponer a las parvadas de pollitas a desarrollar la afección. Aunque se requieren más investigaciones, estos hallazgos establecen la hepatopatía hemorrágica como una condición patológica de las pollitas reproductoras pesadas y pueden ayudar en el diagnóstico y a la prevención del síndrome.

Modulation of folliculogenesis in adult laying chickens by bisphenol A and bisphenol S: Perspectives on ovarian morphology and gene expression.

Both bisphenol A (BPA) and its analog bisphenol S (BPS) are industrial chemicals that have been used to make certain plastic products applied in chicken farms, including food and water containers. They are endocrine disrupting chemicals (EDCs) with xenoestrogenic activities and affect reproductive success in many ways. It was hypothesized that BPA and BPS could adversely affect the folliculogenesis in chickens due to their disruption of the estrogen responses, using either genomic or non-genomic mechanisms. This study investigated the deleterious effects of BPA and BPS on the ovaries when adult layer chickens were orally treated with these EDCs at 50 µg/kg body weight, the reference dose for chronic oral exposure of BPA established by the U.S. EPA. The chickens in both BPA and BPS-treated groups showed a decreased number of the preovulatory follicles. BPA-treated chickens showed a significant decrease in the diameter of F1. Additionally, both BPA and BPS treatments increased the infiltrations of lymphocytes and plasma cells in ovaries. Moreover, it was found that the ovaries of BPS-treated chickens weighed the most among the groups. RNA sequencing and subsequent pathway enrichment analysis of differentially expressed genes revealed that both BPA- and BPS-treatment groups showed significant changes in gene expression and pathways related to reproduction, immune function and carcinogenesis. Taken together, both BPA and BPS are potentially carcinogenic and have deleterious effects on the fertility of laying chickens by inducing inflammation, suggesting that BPS may not be a safe replacement for BPA.

Dietary methionine level alters growth, digestibility, and gene expression of amino acid transporters in meat-type chickens.

Imbalance in nutrients can affect digestibility of amino acids by altering gene expression of amino acid transporters. We investigated digestibility and molecular transporters of essential amino acids in chickens fed a methionine-deficient diet. A total of 40 chicks (23 D old) were randomly assigned to either a control (0.49% methionine) or a deficient (0.28%) diet until 41 D when they were sampled for Pectoralis (P.) major, kidney, ileum, and hypothalamus for mRNA expression analysis. The ileal content was collected for apparent ileal digestibility (AID) analysis. Birds fed the deficient diet had reduced growth and worse feed efficiency compared to control. The AID of methionine was similar between both groups. The AID of other essential amino acids was higher in the deficient group than control. mRNA expression of b0,+ AT and LAT4 were upregulated in the ileum and kidney but LAT1 was downregulated only in kidney of the deficient group compared to control. In the P. major, SNAT1, SNAT2, and CAT1 were upregulated in the deficient group compared to control. A diet deficiency in methionine affects digestibility of essential amino acids and cysteine, but not the digestibility of methionine. The change in digestibility is reflected in the mRNA expression of amino acid transporters across different tissues.

Acute Lameness in a Roller Pigeon ( Columba livia ) with Multicentric Lymphosarcoma.

A 3-yr-old adult female roller pigeon ( Columba livia ) used as part of a breeding pair for an ongoing research study presented with acute left limb lameness. Palpation of the left leg and region revealed a large lump near the coxofemoral joint. The bird was able to ambulate in the cage, but would not brood her hatchling. The bird was humanely euthanized and necropsy was performed. Grossly, multiple large white to pale tan nodules were noted in the pancreas, lung, rib cage, intestines, and unilaterally in the left kidney. Microscopic examination of the various organs revealed neoplastic proliferation of round cells consistent with lymphoblasts. Immunohistochemistry was performed with the use of antibodies to CD3, CD79a, CD20, and CD21 to phenotype the cells. The results indicated that the neoplastic infiltrating cells were predominantly of T-cell origin.

Molecular characterization of Marek's disease virus in a poultry layer farm from Colombia.

Marek's disease (MD) is a lymphoproliferative disease caused by an Alphaherpesvirus, genus Mardivirus, serotype 1 (Gallid Herpesvirus 2, GaHV-2) that includes all known pathogenic strains. In addition to Marek's disease virus (MDV) serotype 1, the genus includes 2 distinct nonpathogenic serotypes: serotype 2 (GaHV-3) and serotype 3 (Meleagridis Herpesvirus 1, MeHV-1) which are used in commercially available vaccines against MD. As a result of vaccination, clinical signs are not commonly observed, and new cases are usually associated with emerging variant strains against which the vaccines are less effective. In this study, a commercial layer farm showing clinical signs compatible with MDV infection was evaluated. Histological lesions and positive immunohistochemistry in the sciatic nerve and thymus were compatible with cytolytic phase of MD. GaHV-2, GaHV-3 and MeHV-1 were identified by PCR and qPCR in blood samples from 17 birds with suspected MD. Analysis of the Meq gene of the Colombian GaHV-2 isolate revealed a 99% sequence identity with Asian strains, and in the phylogenetic analysis clustered with vv+ MDV. The analysis of amino acid alignments demonstrated an interruption of the proline rich region in P176A, P217A and P233L positions, which are generally associated with vv+ strains. Some of these changes, such as P233L and L258S positions have not been reported previously. In addition, primary cell cultures inoculated with lymphocytes isolated from the spleen showed typical cytopathic effect of GaHV-2 at 5 d post infection. Based on the molecular analysis, the results from this study indicate the presence of vv+ MDV infection in commercial birds for the first time in Colombia. It is recommended to perform further assays in order to demonstrate the pathotype characteristics in vivo.

Improved clinicopathologic assessments of acute liver damage due to trauma in Indian ring-necked parakeets (Psittacula krameri manillensis).

Increased activities of certain biochemical enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], lactate dehydrogenase [LDH], alkaline phosphatase [ALP]) have been associated with blunt liver injury in many species. To evaluate changes in plasma hepatic biochemical parameters in acute avian liver disease caused by trauma and to compare biochemical changes with histologic lesions in hepatic parenchyma, 30 healthy fasted Indian ring-necked parakeets (Psittacula krameri manillensis) were divided into 2 groups, and traumatic liver injury was caused by endoscopic liver biopsy (group 1) or by liver biopsy and crushing injury to the hepatic parenchyma with endoscopic forceps (group 2) in anesthetized birds. Blood samples were collected at baseline and at 12, 24, 36, 48, 60, 72, 84, 96, 108, and 120 hours in alternate groups to compare analyte values after injury with those at baseline. Results showed consistently decreased plasma ALP activity (excluding 1 time point) throughout the study, which was thought to be associated with isoflurane administration. Plasma glutamate dehydrogenase activity initially increased but rapidly declined thereafter and was attributed to acute focal hepatocellular injury. In both groups, increases in plasma AST, ALT, and LDH activities was most likely caused by muscle injury because creatine kinase activity was concurrently increased. Compared with baseline values, bile acid concentration and y-glutamyl transferase activity were not affected by liver biopsy or crush injury. Plasma sorbitol dehydrogenase activity was the most specific indicator of liver injury in both groups. Histologic changes correlated poorly with biochemical results, possibly because the small area of hepatic parenchyma that was damaged did not affect enzyme values substantially.

Response of white leghorn chickens to infection with avian leukosis virus subgroup J and infectious bursal disease virus.

The effects of viral-induced immunosuppression on the infectious status (viremia and antibody) and shedding of avian leukosis virus (ALV) were studied. Experimental white leghorn chickens were inoculated with ALV subgroup J (ALV-J) and infectious bursal disease virus (IBDV) at day of hatch with the ALV-J ADOL prototype strain Hcl, the Lukert strain of IBDV, or both. Appropriate groups were exposed a second time with the Lukert strain at 2 wk of age. Serum samples were collected at 2 and 4 wk of age for IBDV antibody detection. Samples for ALV-J viremia, antibody detection, and cloacal shedding were collected at 4, 10, 18, and 30 wk of age. The experiment was terminated at 30 wk of age, and birds were necropsied and examined grossly for tumor development. Neoplasias detected included hemangiomas, bile duct carcinoma, and anaplastic sarcoma of the nerve. Control birds and IBDV-infected birds were negative for ALV-J-induced viremia, antibodies, and cloacal shedding throughout experiment. By 10 wk, ALV-J-infected groups began to develop antibodies to ALV-J. However, at 18 wk the incidence of virus isolation increased in both groups, with a simultaneous decrease in antibody levels. At 30 wk, 97% of birds in the ALV-J group were virus positive and 41% were antibody positive. In the ALV-J/IDBV group, 96% of the birds were virus positive at 30 wk, and 27% had antibodies to ALV-J. In this study, infection with a mild classic strain of IBDV did not influence ALV-J infection or antibody production.

Myxosarcomas associated with avian leukosis virus subgroup A infection in fancy breed chickens.

Formalin-fixed suspect tumors were submitted to the Poultry Diagnostic and Research Center at the University of Georgia (Athens, GA) for diagnosis. Samples were from fancy breed chickens with a history of increased tumor prevalence in both hens and roosters. Microscopically, in all the samples, there were neoplastic proliferations of spindle-shaped cells. The matrix surrounding tumor cells stained positively with Alcian blue at pH 2.5, but neoplastic cells did not stain with periodic acid-Schiff. Immunohistochemistry stains were positive for vimentin and neuron-specific enolase and negative for desmin, smooth muscle actin, and S-100 protein. Tumors were determined to be myxosarcomas. All samples were positive for PCR targeting the gp85 avian leukosis virus (ALV) envelope protein. However, analysis of the predicted amino acid sequences in the envelope gene from three separate samples showed high similarity between them and to ALV subgroup A.

Peer support telephone calls for improving health.

BACKGROUND: Peer support telephone calls have been used for a wide range of health-related concerns. However, little is known about their effects. OBJECTIVES: To assess the effects of peer support telephone calls in terms of physical (e.g. blood pressure), psychological (e.g. depressive symptoms), and behavioural health outcomes (e.g. uptake of mammography) and other outcomes. SEARCH STRATEGY: We searched: The Cochrane Library databases (CENTRAL, DARE, CDSR) (issue 4 2007); MEDLINE (OVID) (January 1966 to December 2007); EMBASE (OVID) (January 1985 to December 2007); CINAHL (Athens) (January 1966 to December 2007), trials registers and reference lists of articles, with no language restrictions. SELECTION CRITERIA: Randomised controlled trials of peer support interventions delivered by telephone call. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data. We present results narratively and in tabular format. Meta-analysis was not possible due to heterogeneity between studies. MAIN RESULTS: We included seven studies involving 2492 participants.Peer support telephone calls were associated with an increase in mammography screening, with 49% of women in the intervention group and 34% of women in the control group receiving a mammogram since the start of the intervention (P 12). The peer support intervention significantly decreased depressive symptomatology at the 4-week assessment (odds ratio (OR) 6.23 (95% confidence interval (CI) 1.15 to 33.77; P = 0.02)) and 8-week assessment (OR 6.23 (95% CI 1.40 to 27.84; P = 0.01). One study investigated the use of peer support for patients with poorly controlled diabetes. There were no significant differences between groups for self-efficacy, HbA1C, cholesterol level and body mass index. AUTHORS' CONCLUSIONS: Whilst this review provides some evidence that peer support telephone calls can be effective for certain health-related concerns, few of the studies were of high quality and so results should be interpreted cautiously. There were many methodological limitations thus limiting the generalisability of findings. Overall, there is a need for further well designed randomised controlled studies to clarify the cost and clinical effectiveness of peer support telephone calls for improvement in health and health-related behaviour.

Detection of reticuloendotheliosis virus by immunohistochemistry and in situ hybridization in experimentally infected Japanese quail embryos and archived formalin-fixed and paraffin-embedded tumours.

Reticuloendotheliosis virus (REV) infection can result in immunosuppression, a runting syndrome, high mortality, acute reticulum cell neoplasia, or T-cell and/or B-cell lymphomas, in a variety of domestic and wild birds. Histopathological changes in REV infection are not sufficient to differentiate it from avian lymphoid leukosis and Marek's disease, and currently there are no available in situ diagnostic methods for detection of active REV presence in pathologic specimens. To develop immunohistochemistry and in situ hybridization assays for detection of REV active infections, experimentally inoculated Japanese quail embryos, and archived formalin-fixed paraffin-embedded tissues from natural and experimental reticuloendotheliosis cases in chickens and turkeys, were examined. The in situ hybridization and immunohistochemistry assays proved to be efficient for the detection of several REV strains in Japanese quail embryos during active infection, whereas these assays were much less sensitive when applied to archived tissue samples from chronically infected birds with lymphoid tumours. The diagnostic assays developed in this study have potential as diagnostic tools for detection of active REV infections.

Management of venous thromboembolism in patients with advanced cancer: a systematic review and meta-analysis.

Venous thromboembolism is common in patients with cancer. However, no management guidelines exist for venous thromboembolism specific to patients with advanced progressive cancer. To help develop recommendations for practice, we have done a comprehensive review of anticoagulation treatment in patients with cancer, with particular focus on studies that included patients with advanced disease. Data from 19 publications, including randomised, prospective, and retrospective studies suggest that: long-term full-dose low-molecular-weight heparin (LMWH) is more effective than warfarin in the secondary prophylaxis of venous thromboembolism in patients with cancer of any stage, performance status, or prognosis; warfarin should not be used in patients with advancing progressive disease; and in patients at high risk of bleeding, full-dose LMWH for 7 days followed by a long-term decreased fixed dose long term can be considered. The optimum treatment duration is unclear, but because the prothrombotic tendency will persist in patients with advanced cancer, indefinite treatment is generally recommended. For patients with contraindications to anticoagulation, inferior-vena-caval filters can be considered, but their use needs careful patient selection. Ultimately, the decision to initiate, continue, and stop anticoagulation will need to be made on an individual basis, guided by the available evidence, the patient's circumstances, and their informed preferences.

Liver granulomas due to Eubacterium tortuosum in a seven-week-old Bobwhite quail.

Three 7-wk-old Bobwhite quail were submitted for necropsy to the Douglas branch of the Georgia Poultry Laboratory Network. Grossly, one bird had multiple white foci in the liver and a mild airsacculitis. In this quail there were multiple hepatic granulomas that contained mats of filamentous bacteria easily seen in hematoxylin- and eosin-stained histologic sections. These bacteria were negative with period acid-Schiff and were not acid fast. Bacteria were gram-positive but were most evident on Warthin-Starry silver-stained sections. The appearance and histochemical characteristics of these bacteria are most consistent with Eubacterium tortuosum.

Retroviral inclusions in the enteric smooth muscle of a tumor-bearing young chicken.

A 15-cm segment of small intestine from a 7-wk-old broiler chicken presented for slaughter was encased by a firm, white mass. Other tissues were grossly unremarkable. Microscopically, the enteric serosa and peripheral muscularis of this segment of small intestine were replaced by a fibrosarcoma. Numerous linear, intracytoplasmic, eosinophilic inclusion bodies were present in smooth muscle cells of the muscularis of the small intestine, and a few similar inclusions were present in the muscularis of the proventriculus. In the heart, there were rare intracytoplasmic inclusions typical of viral matrix inclusions. Ultrastructurally, inclusion bodies in enteric smooth muscle were viral matrix inclusions, and virions resembling avian retroviruses were present in adjacent intercellular spaces. Polymerase chain reaction (PCR) of the deoxyribonucleic acid (DNA) extracted from tumor tissues indicated the presence of proviral DNA of subgroup J avian leukosis virus. This is the first description of the light microscopic appearance of these viral matrix inclusions in enteric smooth muscle.

Chemotaxis plays multiple roles during Helicobacter pylori animal infection.

Helicobacter pylori is a human gastric pathogen associated with gastric and duodenal ulcers as well as specific gastric cancers. H. pylori infects approximately 50% of the world's population, and infections can persist throughout the lifetime of the host. Motility and chemotaxis have been shown to be important in the infection process of H. pylori. We sought to address the specific roles of chemotaxis in infection of a mouse model system. We found that mutants lacking cheW, cheA, or cheY are all nonchemotactic and infect FVB/N mice with an attenuated phenotype after 2 weeks of infection. If infections proceeded for 6 months, however, this attenuation disappeared. Histological and culture analysis revealed that nonchemotactic mutants were found only in the corpus of the stomach, while the wild type occupied both the corpus and the antrum. Further analysis showed that nonchemotactic H. pylori isolates had an increased 50% infectious dose and were greatly outcompeted when coinfected with the wild type. If nonchemotactic mutants were allowed to establish an infection, subsequent infection with the wild type partially displaced the nonchemotactic mutants, indicating a role for chemotaxis in maintenance of infection. The data presented here support four roles for chemotaxis in H. pylori mouse infections: (i) establishing infection, (ii) achieving high-level infection, (iii) maintaining an infection when there are competing H. pylori present, and (iv) colonizing all regions of the stomach.

Response of white leghorn chickens of various genetic lines to infection with avian leukosis virus subgroup J.

In Experiment 1, chickens from various white leghorn experimental lines were inoculated with strain ADOL-Hcl of subgroup J avian leukosis virus (ALV-J) either as embryos or at 1 day of age. At various ages, chickens were tested for ALV-J induced viremia, antibody, and packed cell volume (PCV). Also, at 4 and 10 wk of age, bursal tissues were examined for avian leukosis virus (ALV)-induced preneoplastic lesions with the methyl green-pyronine (MGP) stain. In Experiment 2, chickens harboring or lacking endogenous virus 21 (EV21) were inoculated with strain ADOL-Hcl of ALV-J at hatch. All embryo-inoculated chickens in Experiment 1 tested positive for ALV-J and lacked antibody throughout the experimental period of 30 wk and were considered viremic tolerant, regardless of line of chickens. By 10 wk of age, the incidence of ALV-J viremia in chickens inoculated with virus at hatch varied from 0 (line 0 chickens) to 97% (line 1515); no influence of ALV-J infection was noted on PCV. Results from microscopic examination of MGP-stained bursal tissues indicate that ALV-J can induce typical ALV-induced transformation in bursal follicles of white leghorn chickens. Lymphoid leukosis and hemangiomas were the most common ALV-J-induced tumors noted in chickens in Experiment 1. At termination of Experiment 2 (31 wk of age), 54% of chickens harboring EV21 were viremic tolerant compared with 5% of chickens lacking EV21 after inoculation with ALV-J at hatch. The data indicate that genetic differences among lines of white leghorn chickens, including the presence or absence of EV21, can influence response of chickens to infection with ALV-J.

Tissue tropism and bursal transformation ability of subgroup J avian leukosis virus in White Leghorn chickens.

In Experiment 1, a monoclonal antibody against the envelope glycoprotein (gp85) of subgroup J avian leukosis virus (ALV-J) was used to study the distribution of ALV-J in various tissues of White Leghorn chickens inoculated as embryos with the strain ADOL-Hcl of ALV-J. At 2 and 6 wk of age, various tissues from infected and control uninfected chickens were tested for the presence of ALV-J gp85 by immunohistochemistry. In Experiment 2, using the methyl green-pyronine (MGP) stain, sections of bursa of Fabricius (BF) from chickens of line 15I5 x 7(1), inoculated with ALV-J or Rous-associated virus-1 (RAV-1), a subgroup A ALV, at hatch were examined for transformation of bursal follicles at 4 and 10 wk of age. In Experiment 1, specific staining indicative of the presence of ALV-J gp85 was noted at both 2 and 6 wk of age in the adrenal gland, bursa, gonads, heart, kidney, liver, bone marrow, nerve, pancreas, proventriculus, spleen, and thymus. In Experiment 2, by 10 wk of age, transformed bursal follicles were detected in MGP-stained sections of BF in only one of five (20%) chickens inoculated with ALV-J at hatch, compared with five of five (100%) chickens inoculated with RAV-1. The data demonstrate distribution of ALV-J gp85 in various tissues of White Leghorn chickens experimentally inoculated as embryos with the virus. The data also confirm our previous observation that ALV-J is capable of inducing transformation of bursal follicles, albeit the incidence is less frequent than that induced by subgroup A ALV.

Pathogenicity of two recombinant avian leukosis viruses.

We have recently described the isolation and molecular characteristics of two recombinant avian leukosis subgroup J viruses (ALV J) with an avian leukosis virus subgroup A envelope (r5701A and r6803A). In the present study, we examined the role of the subgroup A envelope in the pathogenesis of these recombinant viruses. Chickens of line 151(5) x 7(1) were inoculated at 1 day of age with r5701A, r6803A, Rous-associated virus type 1 (RAV-1), or strain ADOL-Hcl of ALV-J. At 2, 4, 10, 18, and 32 wk postinoculation (PI), chickens were tested for avian leukosis virus (ALV)-induced viremia, shedding, and neutralizing antibodies. All except one chicken inoculated with the recombinant viruses (98%) developed neutralizing antibodies by 10 wk PI compared with only 16% and 46% of the ADOL-Hcl and RAV-1-inoculated birds, respectively. ALV-induced tumors and mortality in the two groups inoculated with recombinant viruses were different. The incidence of tumors in groups inoculated with r5701A or RAV-1 was 100% compared with only 9% in the groups inoculated with r6803A or ADOL-Hcl. The data suggest that differences in pathogenicity between the two recombinant viruses might be due to differences in the sequence of the 3' untranslated region (presence or absence of the E element), and, therefore, not only the envelope but also other elements of the viral genome play an important role in the pathogenesis of ALV.