Ultrastructural morphology of Cowdria ruminantium in midgut epithelial cells of adult Amblyomma hebraeum female ticks

Amblyomma hebraeum male and female ticks, experimentally infected as larvae with the Ball 3 stock of Cowdria ruminantium, were fed on a heartwater susceptible sheep. The initial attachment of the males was required as a pre-requisite for female attachment. Reticulate bodies were the predominant morphologic form of Cowdria observed in gut epithelial cells after 1-3 days of feeding. Single intermediate bodies and no elementary bodies were observed. Organisms were found within a membrane-bound vacuole and each organism had a double-unit membrane. Infrequently colonies contained homogeneous electron-dense inclusions. Groups of Cowdria organisms within a haemocyte suggested a possible dissemination of organisms from the gut to various other tissues by haemocytes.     

Renal Tubular Cyst Formation in Newborn Rats Treated with p-Cumylphenol

In this study, we investigated the sequential changes in the development of renal tubular cysts in newborn rats treated with p-cumylphenol (PCP). Fifteen animals per sex were treated orally with 300 mg/kg/day of PCP for up to 18 days from postnatal day (PND) 4 and were sacrificed on PNDs 8, 12, 19 and 22 and after a 7 day recovery period. On PNDs 8 and 12, slight dilatation of the collecting ducts was frequently observed in the medulla and slight papillary necrosis was also noted in some cases. These dilated collecting ducts were lined with slightly hyperplastic epithelial cells. On PNDs 19 and 22, multiple large cystic changes arising from the collecting ducts in the outer medulla were seen. These cystically dilated ducts were also lined with hyperplastic epithelial cells. During the dosing period, the labeling index of proliferating cell nuclear antigen in the collecting duct epithelium was higher in the PCP-treated group than in the control group at all time points. After a 7 day recovery period, the cystic change still remained, although the cell density was decreased and the epithelial cells became flattened. On the other hand, basophilic tubules with peritubular lymphoid cell infiltration were multifocally observed in the cortex. In conclusion, PCP induced multiple renal cysts that developed in the collecting ducts of the outer medulla in neonatal rats, and it is suggested that epithelial cell proliferation may play some roles in the induction of cystic lesions.     

Experimental reproduction of porcine proliferative enteritis

Conventional crossbred pigs from different sources and of different weights were examined for susceptibility to porcine proliferative enteritis. The ileal mucosa of pigs with the disease was emulsified and suspended in Mueller-Hinton broth. Pigs weighing 15, 120 and 200 lb (6.8, 54.5 and 91 kg) (four pigs per group) were stressed and inoculated orally with 80 ml of emulsified proliferative ilea. Severe lesions of porcine proliferative enteritis were detected in three of the four pigs weighing 6.8 kg. Mild lesions were detected in two of the four pigs in each of the other two groups. Gross lesions consisted of reticulation of the serosa, and hyperaemia and thickening of the mucosa with either fibrin or blood clots adherent to the mucosal surface. Inflammation, numerous mitotic figures and epithelial cell proliferation were observed microscopically in the crypts. Silver stained sections revealed numerous comma-shaped organisms in the crypts of infected epithelial cells. Using this method, serial reproduction of the disease was accomplished through the passage of fresh and previously frozen inocula. The virulence of the freshly prepared inoculum increased with passage through the host, whereas the inoculum prepared from tissue that had previously been frozen showed a decrease in infectivity and virulence. These data provide strong evidence for the infectious nature of this disease.     

Intestinal trichomonads (Tritrichomonas mobilensis) in the natural host Saimiri sciureus and Saimiri boliviensis

A retrospective study of cecal and colonic tissues from 28 squirrel monkeys (Saimiri sciureus and Saimiri boliviensis) demonstrated enteric trichomonads within luminal crypts. Twenty-one of 28 (75%) had trichomonads in the mucosal epithelium either in cup-like depressions or intraepithelial vacuoles. Organisms were also beneath the superficial luminal mucosal epithelium and between the basement membrane and crypt epithelial cells. Immunoperoxidase staining also identified organisms within the lamina propria and submucosa. Additional histologic changes included mucosal ulceration, multifocal cryptitis, and focal epithelial necrosis. Most areas containing trichomonads did not have an associated inflammatory response.     

Enterocecocolitis associated with intraepithelial Campylobacter-like bacteria in rabbits (Oryctolagus cuniculus)

We examined 28 suckling, weanling, and young adult rabbits with lethargy, inappetence, and mucinous, semifluid feces. Sixteen of the rabbits had intestinal lesions. In eight of these rabbits, the primary changes were multifocal to diffuse epithelial proliferation and accumulation of lymphocytes, macrophages, or both in the lamina propria of the small intestine, cecum, and sacculated colon. In two of these rabbits, the accumulation of macrophages in the lamina propria was extensive. The other eight rabbits had erosive and suppurative cecocolitis, and four of the rabbits with proliferative lesions also had suppurative cecocolitis. In Warthin-Starry-stained sections of affected intestine, curved or spiral bacteria were visible within degenerated or hyperplastic epithelium, in luminal exudate, or in both. Such organisms were sparse or not found in the other 12 rabbits, which did not have intestinal lesions. The bacteria ultrastructurally resembled intraepithelial Campylobacter-like bacteria previously observed in proliferative enteritis in a variety of species and in acute typhlitis in young rabbits. In immunofluorescence tests, Campylobacter-like bacteria in epithelial cells, crypt lumina, and in luminal exudates in both proliferative and erosive lesions bound monoclonal antibodies and polyclonal antisera prepared against intracellular bacteria found in proliferative enteritis in pigs, hamsters, and ferrets. These observations indicate that a condition similar to proliferative enteritis of swine, hamsters, and other species also occurs in laboratory rabbits.     

Immunohistochemical detection of avian pneumovirus in formalin-fixed tissues.

An immunohistochemical staining technique (IHC) was developed to detect avian pneumovirus (APV) antigen in formalin-fixed, paraffin-embedded tissue sections using streptavidin-biotin immunoperoxidase staining. Samples of nasal turbinates and infraorbital sinuses were collected from 4-week-old poults experimentally inoculated with APV and from older turkeys infected during naturally occurring outbreaks of avian pneumovirus. Tissue was fixed in 10% buffered neutral formalin, embedded in paraffin, sectioned and stained. Inflammatory changes were observed microscopically in the mucosa and submucosa of the nasal turbinates and infraorbital sinuses of both experimentally inoculated poults and naturally infected birds. Viral antigen was detected by IHC in the ciliated epithelial cells of nasal turbinates and infraorbital sinuses.     

Microscopic and ultrastructural lesions of the ureter and renal pelvis in sows with regard to Actinobaculum suis infection

Tissues from ureter and renal pelvis of 18 sows naturally (n = 15) and experimentally (n = 3) infected with Actinobaculum suis (former Actinomyces, Eubacterium suis) were studied using light and scanning as well as transmission electron microscopy. The results were compared with the findings from 11 clinically healthy sows as controls. The lesions in both the ureter and renal pelvis of naturally and experimentally infected animals were similar. In severe cases there were necrotizing ureteritis and pyelitis with accumulation of bacterial colonies in some cases. Several superficial epithelial cells were found phagocytosing necrotic debris. In mild cases the main lesions included epithelial cell hyperplasia, desquamation of the superficial epithelial cells and goblet cell metaplasia with intraepithelial cyst formation. The goblet cells were found in the superficial as well as in the intermediate cell layers. Generally, it was observed that severe purulent ureteritis and pyelitis/ pyelonephritis in sows were to be expected only in mixed infection of A. suis with other bacteria. The findings were compared and discussed with the changes in the infected urinary bladder of sows and the alterations induced by urinary tract infection in man.     

Possible relationship of proliferative enteritis in pigs and hamsters

Three- to six-week-old hamsters were orally inoculated with broths containing one of the following cultures: Campylobacter mucosalis; C. hyointestinalis; C. coli; C. jejuni, all of porcine proliferative enteritis origin, or else C. jejuni of hamster origin. Hamsters given the last of those organisms were shown to have colonisation of their intestines by C. jejuni and 36 of 40 developed an acute enteritis. Mild hyperplasia of enterocytes in ileal crypts was evident in one hamster 2 days after it was given C. coli. No other lesions were detected. Further 3-week-old hamsters were orally inoculated with homogenised intestinal mucosa collected from 4 pigs (A-D) affected by proliferative enteritis. Lesions of proliferative enteritis were detected in 7 of 41 hamsters necropsied 10-21 days after being dosed with mucosas B or D. Marked hyperplasia of ileal enterocytes, associated with numerous intracellular Campylobacter-like organisms, were invariably detected in experimentally affected hamsters. No particular Campylobacter sp. was consistently isolated. None of the controls had demonstrable lesions. The results suggested that cross-species transmission of proliferative enteritis was possible from pigs to hamsters. Therefore a common initiating or aetiological agent may be present. No specific organism was identified as filling this role by inoculation of hamsters with pure cultures.     

Proliferative enteropathy involving Lawsonia intracellularis infection in rabbits (Oryctlagus cuniculus)

Five rabbits suffering from diarrhea were diagnosed with proliferative enteropathy (PE). Histopathology revealed a thickened mucosa consisting of hyperplastic intestinal epithelium and infiltration of inflammatory cells mainly consisted of macrophages. In the affected epithelial cytoplasm, numerous curved bacillus-like organisms were observed in the Warthin-Starry silver stain and electron microscopy observation. In polymerase chain reactions, Lawsonia intracellularis-specific DNA fragment were amplified from affected ileal tissue extracted DNA in each case and present 5 cases were confirmed to be L. intracellularis infection. Serum collected from the affected rabbit was immunohistochemically reactive with L. intracellularis in tissue sections from pigs with porcine proliferative enteropathy, as well as with tissue sections from the five affected rabbits. Thus, serum obtained from the affected rabbit may be applicable to immunohistochemical detection for L. intracellularis infection in other species.     

Demonstration of colonies of Cowdria ruminantium in midgut epithelial cells of Amblyomma variegatum

The development of colonies of Cowdria ruminantium was studied in midgut epithelial cells of adult Amblyomma variegatum that had become infected by feeding as nymphs on cattle with experimentally induced heart-water disease. Colonies were not observed in gut tissues obtained from nymphs during the feeding period, but were present in midgut epithelial cells of ticks obtained at 15 days after they were replete through molting to the adult stage. Colonies were small (1 to 10 micron) initially, but as tick development progressed, their diameter increased to as much as 60 micron. With electron microscopy, colonies were observed to be membrane bound and contained pleomorphic organisms that were reticulated. The organisms seemed to be dividing by binary fission. Many colonies contained a large, electron-dense inclusion that was morphologically similar to hemoglobin deposits found in the cytoplasm of midgut epithelial cells of recently fed ticks. Cowdria ruminantium was often observed adhered to these inclusions.     

Field studies: pseudomonas pneumonia of mink

Epizootics of pneumonia in mink caused by Pseudomonas aeruginosa were investigated to characterize the serotype of organisms and to identify possible predisposing factors. Most epizootics were associated with P aeruginosa Fisher serotype 1, and a few were associated with 3 other serotypes. There were no predisposing factors identified that could be used to differentiate farms affected and those not affected with pseudomonas pneumonia. Cultural studies indicated that P aeruginosa was present in mink from affected and nonaffected herds. Organisms isolated included serotypes associated with naturally occurring disease. Serostudy results were similar among herds. A prospective field vaccination trial did not yield definitive results, since only slight losses occurred in both vaccinated and nonvaccinated mink. Significant levels of antibody were detected in mink 15 to 17 weeks after they were given a single dose of P aeruginosa lipopolysaccharide vaccine.     

用原位杂交技术对牛组织中FMDV RNA检测和定位

采用原位杂交技术对6头试验牛易感染组织中的FMDVRNA进行了检测和定位。结果显示，接毒后7～28d4头牛舌上皮组织、7～21d的喉咽部有强阳性染色；接毒后35d的牛及正常对照牛舌上皮没有阳性染色；接毒牛及对照牛的扁桃体、淋巴结和蹄叉等其他组织中均没有阳性染色，表明牛舌上皮和喉咽部上皮组织中感染了FMDV，本研究为进一步阐明FMDV在宿主体内的持续感染机理提供极有价值的线索。     

Ocular lesions of bovine malignant catarrhal fever

The ocular lesions of bovine malignant catarrhal fever were characterized in 15 naturally occurring and eight experimentally induced cases of the disease. Consistent findings included: lymphocytic vasculitis of retinal, scleral, posterior ciliary, and uveal vessels; uveitis, especially involving ciliary processes, ciliary body, and iris; and keratitis with corneal edema, neovascularization, and epithelial and endothelial degeneration. Lymphocytic ciliary neuritis and optic meningitis were found less frequently. Ultrastructural examination of the ciliary body and iris from one experimental calf confirmed that most infiltrating mononuclear cells were lymphocytes. The uveitis, vasculitis, and keratitis of malignant catarrhal fever were probably immune-mediated.     

Gastritis and intestinal metaplasia in Syrian hamsters infected with Helicobacter aurati and two other microaerobes

Chronic gastritis and intestinal metaplasia associated with naturally occurring colonization by Helicobacter aurati and two other microaerobic species were observed in Syrian hamsters. Thirty-five hamsters, between 7 and 12 months of age, were evaluated from two research and three commercial facilities. Microaerobic bacteria were cultured from the hamster stomachs. These bacteria included H. aurati, a fusiform, urease-positive species; a second novel helical, urease-negative Helicobacter sp.; as well as a smaller, urease-negative Campylobacter sp. Southern blot analysis detected Helicobacter spp. DNA in the gastric tissues of all 35 hamsters; 15 hamsters also had Campylobacter sp. DNA in their gastric tissues. When examined by light microscopy, argyrophilic bacteria consistent with H. aurati or the second Helicobacter sp. were present in antral sections of 12 out of the 15 hamsters where bacteria were seen, while 9 out of the 15 hamsters had bacteria resembling the Campylobacter sp. The presence of Helicobacter spp. but not the presence of Campylobacter sp. was significantly correlated to gastritis severity (P < 0.0001 for Helicobacter spp., P = 0.6025 for Campylobacter sp.) and intestinal metaplasia, as measured by numbers of goblet cells (P = 0.0239 for Helicobacter spp., P = 0.5525 for Campylobacter sp.). Severely affected hamsters also had Giardia sp. within their metaplastic gastric pits. Hamsters with naturally occurring helicobacter-associated gastritis provide a model for studying the development of intestinal metaplasia and gastric giardiasis in H. pylori-infected humans.     

Immunohistochemical and histopathological findings of ovine pulmonary adenocarcinoma (Jaagsiekte) in Egyptian sheep

Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring retrovirus-induced transmissible lung cancer in sheep. Lungs and associated (bronchial and mediastinal) lymph nodes of seven sheep with OPA were examined. Lungs had few multifocal consolidated slightly elevated gray to white masses ranging from 0.5 to 3 cm in diameter. Histopathologically, these masses appeared as well-differentiated acinar adenocarcinoma with little evidence of anaplasia. The acini composed of well-differentiated cuboidal to low columnar epithelium with clear or vacuolated cytoplasm and low mitotic index. No metastases were observed in the bronchial and mediastinal lymph nodes of any animal. The presence of Jaagsiekte sheep retrovirus (JSRV) was demonstrated in the lungs by immunohistochemistry. JSRV protein was detected in all tumor epithelial cells, histologically normal alveolar type II cells, and few bronchiolar epithelial cells, alveolar macrophages, lymphocytes, and plasma cells. This study is the first to confirm the presence of natural OPA in Egypt.     

Detection of disease-specific PrP in the distal ileum of cattle exposed orally to the agent of bovine spongiform encephalopathy

The immunohistochemical localisation of the disease-specific protein, PrP(Sc), was examined in the distal ileum of cattle up to 40 months after they had been exposed orally to the agent of bovine spongiform encephalopathy (BSE), in the intestines and mesenteric lymph nodes of an additional group of cattle, killed six months after a similar exposure, and in the distal ileum of naturally occurring clinical cases of BSE. PrP(Sc) was detected, mainly in macrophages, in a small proportion of the follicles of Peyer's patches in the distal ileum of the experimentally exposed cattle throughout much of the course of the disease. The observations are in agreement with the infectivity data derived from mouse bioassays of the distal ileum. At the later stages of the disease, the proportion of immunostained follicles increased as the total number of follicles decreased with age. In the additional experimental group of cattle, PrP(Sc) was confined to the Peyer's patches in the distal ileum. No immunostaining was detected in the lymphoid tissue of the distal ileum of naturally occurring clinical cases of BSE. In some of the clinically affected experimentally induced and naturally occurring cases of BSE there was sparse immunostaining of the neurons of the distal ileal myenteric plexus.     

A freeze-etching study on experimental murine mastitis.

Streptococcal mastitis was produced experimentally in mice inoculated by the intramammary route; freeze-etched preparations from the affected mammary glands were studied by electron microscopy. The inoculated cocci were seen free in the acinar lumen, within luminal phagocytes and within cells of the epithelium. No significant pathological changes were noted in the junctional complexes between secretory epithelial cells. The results were comparable to those obtained by ultrathin sectioning and indicated that, while cocci can transfer from the acinar lumen into the substance of the epithelium and towards a subepithelial location, the junctional complexes between epithelial cells present a potential barrier to movement through the intercellular spaces.     

Immunohistochemical evaluation of inflammatory infiltrate in the skin and lung of lambs naturally infected with sheeppox virus

The present study describes immunophenotypic characteristics of inflammatory infiltrate in the skin and lung of lambs naturally infected with sheeppox virus (SPV). Three lambs revealed typical cutaneous and pulmonary lesions of sheeppox. Histologically, cutaneous and pulmonary lesions consisted of hyperplastic and/or degenerative changes in the epithelium with mononuclear cells, neutrophils, and typical sheeppox cells (SPCs), which had a vacuolated nucleus and marginated chromatin with occasional granular intracytoplasmic inclusions. The inflammatory infiltrate in pox lesions in both skin and lung was characterized by the presence of MHC II+ dendritic cells, CD4+, CD8+, gammadelta+ T cells, IgM+ cells, and CD21+ cells. Loss of expression of MHC I and MHC II antigens was observed in the affected areas of skin and lung. SPCs, stained with anti-SPV antibody, were also positive for CD14 and CD172A, antigens expressed on monocytes and macrophages. CD14 and CD172A negative SPCs were considered to be SPV infected degenerated epithelial cells or fibroblasts.     

A case of equine abortion caused by Encephalitozoon sp

A Lippizan mare aborted a male fetus a few days before the expected foaling date without showing any clinical sings. Focal lympho-histiocytic hepatitis in the foal and multiplex focal lympho-histiocytic villitis accompanied by villus necroses and marked hypertrophy of chorionic epithelial cells in the arcades were observed. Elongated nucleated organisms were seen in groups in vacuoles or solitarily located in the cytoplasm of the chorionic epithelial cells. The organisms were in large numbers and often extracellularly in areas of villitis and villus necroses. They were Gram-positive, stained with haematoxylin and eosin (HE), periodic acid-Schiff (PAS) and Giemsa, weakly with Warthin-Starry silver stain but not with G?m?ri's methenamine-silver stain. By ultrastructural and immunohistochemical examinations, the organisms were identified as microsporidia belonging to the genus Encephalitozoon. No Encephalitozoon organisms were detected in the fetal organs. This is the first reported case of equine abortion induced by Encephalitozoon sp. in Europe. Although abortion induced by Encephalitozoon is rare, microsporidia should be considered a differential diagnosis for intracellular organisms observed in the chorionic epithelial cells of horses.