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.     

Scanning electron microscopic study of the lower respiratory tract in calves and adult cattle

The surface characteristics of the lower respiratory tract of two groups of cattle were studied with the scanning electron microscope. Group A comprised six one-week-old calves and group B four adult cows. None of the animals had overt respiratory disease or gross morphological evidence of pulmonary lesions. The trachea, bronchi, bronchioles and alveoli of the cranial and the caudal lobes of the right lung were examined. In both groups the luminal surface of the trachea and large bronchi were completely covered by cilia, apparently forming an efficient mucociliary escalator. In the adult animals there were some patchy areas in the trachea and large bronchi devoid of ciliated cells; these were considered abnormal. In the bronchi, non-ciliated cells, mainly mucus-secreting, were not easily identified unless they were discharging secretion. In small bronchi, non-ciliated cells were more evident and easily seen. The bronchioles had many non-ciliated cells and very few ciliated cells capable of forming a complete carpet for a mucociliary escalator. Types 1 and 2 alveolar epithelial cells and alveolar macrophages were identified in both groups. Pores of Kohn were found in the alveolar walls in all animals.     

Scanning electron microscopic studies of Mycoplasma gallisepticum infection in embryonic tracheae

Mycoplasma gallisepticum (MG) was used to infect chicken embryos, and scanning electron microscopy was used to examine the morphologic changes in the tracheae. Tracheae harvested from embryos infected with MG for 5 days showed extensive deciliation, surface erosion, and inflammatory cell infiltration. Embryonic tracheal explants infected with MG for 6 hr showed the same deciliation and surface erosion. The damage to the tracheal surface caused by MG at the embryonic stage might play a role in the pathogenesis of MG infection.     

Pathologic changes caused by transplacental infection with an adenovirus-like agent in pigs

Five hysterectomy-derived colostrum-deprived pigs housed in individual cages with positive ventilation developed severe skin cyanosis and edema of the subcutaneous tissues in the submandibular, thoracic, and abdominal regions. The 5 pigs were killed 7 to 10 days after birth. Eosinophilic intranuclear inclusion bodies were found in endothelial cells of capillary and small blood vessels throughout the body. Ultrastructurally, nuclei of these affected endothelial cells contained small crystalline arrays of virus particles, which were considered to belong to the adenovirus-like group from their size and structure. The present results indicated that the porcine adenovirus-like agent might also have the ability to produce transplacental infection.     

Scanning electron microscopy of the respiratory epithelium of chicks fumigated with formaldehyde vapour

1. Hatching chicks were exposed to 10.9 ppm of formaldehyde vapour during the last 3 d of incubation in a commercial situation.

2. Samples from pre‐selected regions of the entire respiratory tract, taken at 0, 6, 30 and 54 h post‐vaporisation of formaldehyde, were examined by scanning electron microscopy for surface morphological features and associated pathological changes.

3. Clumping of cilia, blebs on the cilial wall, deciliation and exfoliation of the epithelium were all observed under the scanning electron microscope.

4. Lesions were more severe in chicks exposed for 54 h as compared to those exposed for 6 and 30 h. There were no regional differences in the lesions throughout the respiratory tract of all the chicks.

5. Limited observations suggest that the passage of formaldehyde vapour across the egg shell wall may influence the morphology of the respiratory lining of the developing embryo.     

鸡呼吸型传染性支气管炎的诊治

鸡呼吸型传染性支气管炎是由冠状病毒引起的一种急性高度接触传染性的呼吸道疾病。近两年来在我地区传播较为迅速,危害极其严重。因临床与非典型鸡新城疫、鸡败血型支原体感染症状颇为相似,往往易被误诊,给养鸡业带来了很大影响,笔者根据多年来的门诊实践,现将鸡呼吸型传染性支气管炎的诊断和防治对策浅谈如下:一、发病情况:2001年10月中旬,海安镇村风理村二组某养鸡户饲养的2300羽高产蛋鸡在230日龄时,突然出现呼吸症状,气喘和微咳,同时伴有少食、精神萎蘼等症状,产蛋率由93%下降至70%左右,无鸡只死亡。二、临床症状:病鸡食欲不振,采食量明…     

A scanning electron microscopic study of the equine upper respiratory tract

The surface features of the upper respiratory tract of 20 clinically normal horses of various ages and types were studied with scanning electron microscopy. In the rostral part of the nasal cavity, there was a wide zone of non-ciliated epithelium whereas, caudally, the surface was well ciliated. This latter type of epithelium extended into the nasopharynx and guttural pouches although scattered areas of non-ciliated microvillous cells were also found.     

Scanning and transmission electron microscopic study of equine infectious anemia virus.

Scanning and transmission electron microscopy were used to study in detail the morphogenesis and replication of equine infectious anemia virus (EIAV) in cultured, persistently infected equine fetal kidney fibroblasts. The EIAV was shown by thin-section electron microscopy to resemble morphologically more closely the members of the genus Lenti-virus in the family Retroviridae than other genera. Scanning electron microscopy demonstrated budding virus on only about 5% of the equine fetal kidney fibroblasts; however, the entire surface of these cells was involved in viral replication. Except where virus budding was observed, EIAV-infected cells were smooth and free of the topographic surface alterations characteristic of cells transformed by type C retroviruses. The morphologic relationship of EIAV and pathologic manifestations of EIAV infection to those of other Retroviridae are discussed.     

Light and electron microscopic studies on liver histology in chicks fed aflatoxin

This study was carried out under both light and electron microscopy to investigate the effects on liver carbohydrate and lipid metabolism caused by aflatoxin (AF) fed to chicks. Twenty broiler chicks were used. The birds were housed in electrically heated battery cages and exposed to light for 24 h. Feed and water were provided ad libitum. The animals were allocated to two groups each made up of 10 broilers. Total aflatoxin levels of zero (0) and 5 mg of AF/kg feed (81.05% AFB1, 8.79% AFG1, 6.06% AFB2, and 4.10% AFG2) added to a commercial diet, were fed to chicks from hatching up to 3 weeks of age, when the experiment was terminated. The chicks were executed by cervical dislocation and liver samples were obtained for light and electron microscopy. Oil red 'O', Sudan Black B, periodic acid Schiff (PAS) and Best's carmine stains were used to reveal fat and glycogen in the liver. Histological changes in hepatocytes included increased lipid droplets, high glycogen content, and mild mononuclear cell infiltration in the portal areas. Ultrastructural findings were destruction of rough endoplasmic reticulum (rER), reduction in mitochondrial size, enlargement of bile canaliculi, and cisternal dilatation of the smooth endoplasmic reticulum (sER).     

Scanning electron microscopic studies on the red pulp of the mink spleen

In order to obtain three-dimensional information on the fine architecture of the red pulp of the mink spleen, especially the circulation pattern in the red pulp, perfusion-fixed and freeze-cracked specimens were examined with a scanning electron microscope. A latticework was formed by elongated endothelial cells (rod cells) with side processes and the spongy reticular tissue. The outer surface of the sinus was covered with fine processes of reticular cells. Numerous sheathed arteries were found in the splenic cord. The sheath was composed of a few layers of flat reticular cells. The arterial capillaries of the red pulp opened directly into the cordal space. No evidence could be detected to prove or suggest any direct continuity between arterial capillaries and splenic sinuses. These results strongly support the concept of "open circulation", at least in the red pulp of the mink spleen, with the possibility of a "functionally closed circulation" under some physiological conditions.     

山东省传染性支气管炎病毒分离株的电镜观察

从山东省分离到4株病毒株，经病理剖检、鸡胚传代，血凝检测、动物回归、电镜和免疫电镜观察确证为传染性支气管炎病毒。将分离毒分别接种SPF鸡胚，制备各自的阳性血情，经磷钨酸负染，电镜和免疫电镜观察。可见到典型的冠状病毒粒子，病毒的直径界于60－200mm之间，呈多形性，有囊膜，个别有纤突。病毒大量聚集，各株病毒在形态上无差异。     

Scanning electron microscopic studies of megakaryocytes and platelet formation in the dog and rat

Megakaryocyte morphology and platelet formation in canine and murine bone marrows were studied by scanning electron microscopy. In situ-fixed bone marrow preparations and cell suspensions of bone marrow provided complementary information for the 2 species (dogs and rats). Cylindrical processes (proplatelets) of variable length and thickness, originating from the megakaryocyte surface, were in the larger marrow sinusoids and the central vein. Regional constrictions along the length of proplatelets, particularly near their apical region, and the presence of fragments of such processes supported the concept of platelet formation through segmentation of proplatelets. Megakaryocytes presented varied morphology. Surface features resembling platelets were observed on megakaryocytes, indicating that platelets may have been released through surface budding. In conclusion, megakaryocytes formed long proplatelet processes that actively migrated to venous sinusoids to release platelets by fragmentation. Scanning electron microscopy analysis revealed a complex and variable megakaryocyte surface topography. The platelet-like structures on megakaryocyte surfaces may represent platelet release by a budding mechanism. The similarity between murine platelet release and canine platelet release demonstrates that data from rodent models may be applicable to nonrodents.     

Experimental caprine coccidiosis caused by Eimeria arloingi: Morphopathologic and electron microscopic studies

The progressive morphohistopathologic changes, distribution pattern of lesions and ultrastructural characteristics in Eimeria arloingi infection were investigated in experimentally infected kids. The 18 newborn animals allocated to 3 equal groups. Two of groups, A, B were inoculated with a single dose of 1 × 10³ and1 × 10⁵ sporulated oocysts of E. arloingi, respectively. At 7, 14, 21, 28, 35, and 42 days postinoculation (DPI), 1 kid from each group was necropsied for pathologic and ultrastructural studies. Progressive lesions were present at 21, 28, 35 and 42 DPI in the jejunum, ileum, cecum with fewer in the duodenum and proximal colon. The oocysts shedding begin between 16 to 18 DPI. Grossly, minimal changes were observed at 21 DPI as few whitish plaques or nodules and advanced lesions at 42 DPI as pseudoadenomatous pattern in the mucosa and a cerebriform pattern on the serosal surface of jejunum and ileum. Early histopathologic lesions due to schizogony phase were including presence of intracytoplasmic developmental stages of the parasite such as trophozoites, immature to mature schizonts and mild infiltration of inflammatory cells. In late lesions due to various stages of gametogony, the histological pattern was mainly remarkable hyperplasia of the villi and crypts epithelial cells, eventually developed into papillary projections of reactive epithelium. The mesenteric lymph nodes showed a few numbers of large schizonts in the cortical lacteals. This study showed E. arloingi as a highly pathogenic species for kids, the incubation period was 16–18 days and the main target organ was jejunum with characteristic morphohistopathologic lesions.     

Investigations of an enteric infection of cockatoos caused by an enterovirus-like agent

An enteric infection in cockatoos associated with a 30 nm diameter enterovirus-like agent seen in faeces and intestinal epithelial cells is described. The disease is characterised by intractable, profuse, mucoid diarrhoea, weight loss, dehydration and death. Lesions in the intestine consist of villous atrophy, villous fusion, enterocyte hyperplasia and, in some cases, chronic inflammation. Affected birds so far examined have concurrent psittacine beak and feather disease.     

Strain specific antibodies revealed by immunoabsorption studies with avian infectious bronchitis virus

Rabbit antisera prepared against the Massachusetts 41 (M41) strain of avian infectious bronchitis virus (IBV) and absorbed with chick embryo immunoabsorbent produced multiple precipitin lines in immunodouble-diffusion (IDD) tests with homologous or heterologous strains of virus. These precipitin lines were all removed by absorption with concentrated M41 virus preparations, but repeated absorption with concentrated, purified preparations of IBV strains: T, Holte, Connecticut, Beaudette or H120 failed to remove all precipitin lines produced to M41 virus, although all those to the heterologous viruses were removed. The remaining line(s) produced with M41 virus by sera absorbed with different heterologous viruses showed identity in IDD tests and was associated with the surface projections of the virus.