Porphyrin Accumulation and Biliary Lithiasis Causing Diffusely Black Livers in Broiler Chickens.

Two 7-wk-old broiler chickens presented with uniformly black livers upon postslaughter examination, while all other organs as well as their carcasses were grossly normal. No clinical signs were reported by the field veterinarian prior to slaughter. Other broiler chickens within the same flock were unaffected. Microscopically, the liver exhibited variably sized, globoid concrements that were dark brown to green-brown and birefringent under polarized light. Ultrastructurally, concrements consisted of radially arranged electron-dense crystal spicules. Concrements were located in hepatocytes, within ecstatic bile canaliculi, or surrounded by small clusters of macrophages. Liquid chromatography assay determined the presence of protoporphyrin IX in the affected liver.Two 7-wk-old broiler chickens presented with uniformly black livers upon postslaughter examination, while all other organs as well as their carcasses were grossly normal. No clinical signs were reported by the field veterinarian prior to slaughter. Other broiler chickens within the same flock were unaffected. Microscopically, the liver exhibited variably sized, globoid concrements that were dark brown to green-brown and birefringent under polarized light. Ultrastructurally, concrements consisted of radially arranged electron-dense crystal spicules. Concrements were located in hepatocytes, within ecstatic bile canaliculi, or surrounded by small clusters of macrophages. Liquid chromatography assay determined the presence of protoporphyrin IX in the affected liver.

Intestinal Tropism of an Infectious Bronchitis Virus Isolate Not Explained by Spike Protein Binding Specificity.

An infectious bronchitis virus (IBV) with an unusual enteric tropism (CalEnt) was isolated from a California broiler flock exhibiting runting-stunting syndrome. IBV was detected in the small intestine, but not in the respiratory tract or kidney. During virus isolation in embryos, it did not replicate in chorioallantoic membrane (CAM) but could be recovered from intestines. Its S1 protein showed 93% amino acid sequence identity to a California variant isolated in 1999 (Cal99). Intestinal lesions were reproduced following ocular/nasal inoculation of specific-pathogen-free chickens, but respiratory signs and lesions were also present. The virus was detected in both respiratory and intestinal tissues. To determine whether the novel tropism of IBV CalEnt was due to an increased ability of its S1 protein to bind to the intestinal epithelium, we compared the binding of soluble trimeric recombinant S1 proteins derived from CalEnt and Cal99 to chicken tissues. Contrary to expectations, the CalEnt S1 protein did not bind to small intestine and, unlike Cal99 S1, did not bind to the respiratory epithelium or CAM. Using only the CalEnt S1 N-terminal domain or including the S2 ectodomain (lacking membrane and cytoplasmic domains), which have been shown to improve ArkDPI S1 protein binding, did not lead to detectable binding at the standard protein concentration to any tissue tested. Our results indicate no/poor binding of the CalEnt spike protein to both respiratory and intestinal tissues and thus do not support better attachment to intestinal epithelial cells as a reason for CalEnt's extended tropism. These results might reflect shortcomings of the assay, including that it does not detect potential contributions of the S1 C-terminal domain to attachment. We used bioinformatic approaches to explore the possibility that the unique tropism of CalEnt might be a result of functions of the S protein in cell-entry steps subsequent to attachment. These analyses suggest that CalEnt's S2 coding region was acquired through a recombination event and encodes a unique amino acid sequence at the putative recognition site for the protease that activates the S protein for fusion. Thus, S2 activation by tissue-specific proteases might facilitate CalEnt entry into intestinal epithelial cells and compensate for poor binding by its S1 protein.

Tropismo intestinal de un aislamiento del virus de la bronquitis infecciosa con una especificidad de unión a la proteína espícula inusual. Se aisló un virus de la bronquitis infecciosa (IBV) con un tropismo entérico inusual (CalEnt) de una parvada de pollos de engorde de California que presentaba síndrome de retraso en el crecimiento. Se detectó al virus de bronquitis en el intestino delgado, pero no en el tracto respiratorio o en el riñón. Durante el aislamiento del virus en huevos embrionados de pollo, no se replicó en la membrana corioalantoidea (CAM), pero pudo recuperarse de los intestinos. Su proteína S1 mostró una identidad de secuencia de aminoácidos del 93% con una variante de California aislada en el año 1999 (Cal99). Las lesiones intestinales se reprodujeron después de la inoculación ocular/nasal de pollos libres de patógenos específicos, pero también hubo signos y lesiones respiratorias. El virus se detectó en los tejidos respiratorios e intestinales. Para determinar si el nuevo tropismo de este virus de la bronquitis infecciosa CalEnt se ocasionaba por una mayor capacidad de su proteína S1 para unirse al epitelio intestinal, se comparó la unión a los tejidos de pollo de las proteínas S1 recombinantes triméricas solubles derivadas de los virus CalEnt y Cal99. Contrariamente a lo esperado, la proteína CalEnt S1 no se unió al intestino delgado y a diferencia del virus Cal99 S1, no se unió al epitelio respiratorio o CAM. Mediante el uso de solo el dominio N-terminal de la proteína S1 del virus CalEnt o por la inclusión del ectodominio S2 (que carece de dominios de membrana y citoplasmáticos), que se ha demostrado mejora la unión de la proteína S1 del serotipo Arkansas DPI, no se observó una unión detectable a ningún tejido analizado a la concentración de proteína estándar. Estos resultados indican una unión nula o deficiente de la proteína de la espícula del virus CalEnt a los tejidos respiratorios e intestinales y por lo tanto, no respaldan la preferencia de la unión a las células epiteliales intestinales como una razón para el tropismo extendido del virus CalEnt. Estos resultados pueden reflejar las deficiencias del ensayo, incluyendo el hecho de que no detecta posibles contribuciones del dominio C-terminal de la proteína S1 en la unión. Se utilizaron enfoques bioinformáticos para explorar la posibilidad de que el tropismo único del virus CalEnt podría ser el resultado de las funciones de la proteína S en los pasos de entrada a las células posteriores a la unión. Estos análisis sugieren que la región de codificación S2 del virus CalEnt se adquirió a través de un evento de recombinación y codifica una secuencia de aminoácidos única en el supuesto sitio de reconocimiento de la proteasa que activa la proteína S para la fusión. Por lo tanto, la activación de S2 por proteasas específicas de tejido podría facilitar la entrada del virus CalEnt en las células epiteliales intestinales y compensar la unión deficiente por su proteína S1.

Otitis and meningoencephalitis associated with infectious coryza ( Avibacterium paragallinarum) in commercial broiler chickens.

Infectious coryza, caused by Avibacterium paragallinarum, is an acute respiratory disease of poultry that can result in substantial morbidity, mortality, and economic losses. In March 2017, the Turlock branch of the California Animal Health and Food Safety laboratory system encountered an unusual clinical and pathologic presentation of infectious coryza in 6 live, 29-d-old, commercial broiler chickens that were submitted for diagnostic investigation. Antemortem evaluation revealed severe neurologic signs, including disorientation, torticollis, and opisthotonos. Swollen head-like syndrome and sinusitis were also present. Histologically, severe sinusitis, cranial osteomyelitis, otitis media and interna, and meningoencephalitis were noted, explaining the clinical signs described. A. paragallinarum was readily isolated from the upper and lower respiratory tract, brain, and cranial bones. Infectious bronchitis virus (IBV) was also detected by PCR, and IBV was isolated in embryonated chicken eggs. Based on sequencing analysis, the IBV appeared 99% homologous to strain CA1737. A synergistic effect between A. paragallinarum and IBV, resulting in exacerbation of clinical signs and increased mortality, may have occurred in this case. A. paragallinarum should be considered among the possible causes of neurologic signs in chickens. Appropriate media should be used for bacterial isolation, and the role of additional contributing factors and/or complicating agents should be investigated in cases of infectious coryza.

Bilateral malacia associated with sodium poisoning in turkey poults.

Improper cleaning of the water storage tank resulted in a toxic concentration of sodium in drinking water in a commercial turkey flock. Within the first week after placement 40% of the birds in the flock died. Clinically, poults were depressed and weak, huddled together, and reluctant to walk. At necropsy the birds had crops and gizzards filled with rice hulls, moderately swollen livers, distended gall bladders, and congested lungs. Neither ascites nor round heart was observed. The major microscopic lesion was multifocal symmetrical malacia of brain and spinal cord. Laboratory results revealed a high concentration of sodium in water (2340 mg/liter). The concentration of sodium in brain and liver ranged from 1870 to 2680 (mean = 2185; SD = 321.5) mg/liter wet weight and from 1810 to 2360 (mean = 2191.67; SD = 193.2) mg/liter wet weight, respectively, whereas the normal expected sodium concentration in the brain and liver tissues from young turkeys (< 7 days old) that were submitted for other causes averaged 1233 and 983 mg/liter wet weight, respectively. Based on the histological and toxicological results, a diagnosis of salt poisoning was made. This case investigation demonstrated that sodium analysis of brain and liver are diagnostically useful when confirming sodium poisoning in young turkeys.