Histophilus somni host-parasite relationships

Histophilus somni (Haemophilus somnus) is one of the key bacterial pathogens involved in the multifactorial etiology of the Bovine Respiratory Disease Complex. This Gram negative pleomorphic rod also causes bovine septicemia, thrombotic meningencephalitis, myocarditis, arthritis, abortion and infertility, as well as disease in sheep, bison and bighorn sheep. Virulence factors include lipooligosaccharide, immunoglobulin binding proteins (as a surface fibrillar network), a major outer membrane protein (MOMP), other outer membrane proteins (OMPs) and exopolysaccharide. Histamine production, biofilm formation and quorum sensing may also contribute to pathogenesis. Antibodies are very important in protection as shown in passive protection studies. The lack of long-term survival of the organism in macrophages, unlike facultative intracellular bacteria, also suggests that antibodies should be critical in protection. Of the immunoglobulin classes, IgG2 antibodies are most implicated in protection and IgE antibodies in immunopathogenesis. The immunodominant antigen recognized by IgE is the MOMP and by IgG2 is a 40 kDa OMP. Pathogenetic synergy of bovine respiratory syncytial virus (BRSV) and H. somni in calves can be attributed, in part at least, to the higher IgE anti-MOMP antibody responses in dually infected calves. Other antigens are probably involved in stimulating host defense or immunopathology as well.     

A pleomorphic adenoma of the lacrimal gland in a dog

A 13-year-old female mongrel dog had a pleomorphic adenoma of the lacrimal gland in the right upper orbit. The tumor measured 3.8 x 3.0 x 3.3 cm, appeared white, round, and firm, and pressed the right globe and surrounding tissues. Histopathologically, the tumor had a thin connective tissue capsule and was composed of tubules with two cell types, some resembling luminal epithelial cells making up the tubular structures and the other of myoepithelial cells. Epithelial tubules were disposed in an adenomatous fashion and separated from each other by proliferating pleomorphic myoepithelial cells. Immunohistochemically, large numbers of the luminal epithelial cells revealed an immunopositive reaction against keratin/cytokeratin (AE1/AE3), and some epithelial cells reacted against cytokeratin 14. Spindle-shaped myoepithelial cells revealed an immunopositive reaction against cytokeratin 14, alpha-smooth muscle actin, and vimentin. A small number of myoepithelial cells reacted against desmin. S-100 protein immunopositivity was frequently found in luminal epithelial cells and rarely in the pleomorphic myoepithelial cells. Glial fibrillary acidic protein positivity was commonly found in myoepithelial cells, myxoid matrices, and intracystic materials, but not in luminal epithelial cells.     

Ultrastructural pathology of Bordetella avium infection in turkeys

One-day-old turkeys were infected intranasally with Bordetella avium, and tracheas were examined by scanning and transmission electron microscopy at 1 to 5 weeks post-inoculation (PI). The predominant ultrastructural lesions were progressive loss of ciliated epithelium with replacement by nonciliated cells, bacterial colonization of ciliated cells, membrane-bound crystalline inclusions in cytoplasma of epithelial cells, depletion of mucous granules, and distortion of tracheal rings and the mucosal surface. Tracheal surface exudates consisted of mucus, necrotic cells, heterophils, and fibrin. Ciliated cells were replaced by immature cuboidal cells characterized by abundant rough endoplasmic reticulum with small numbers of electron-dense mucous granules in the apical cytoplasm. Bacterial surfaces were rough and contained numerous pleomorphic, knob-like structures, 20-50 nm in diameter. Other changes included enlarged mucosal gland openings, cell extrusion marks, pleomorphic microvilli, and cells with small numbers of short cilia.     

Lesions in Brangus cattle with Chediak-Higashi syndrome

Hair, peripheral blood leukocytes, and other tissues from two related Brangus calves with phenotypic characteristics of Chediak-Higashi syndrome were examined by light and electron microscopy. Enlarged, pleomorphic, cytoplasmic granules, morphologically compatible with lysosomes, were seen in several neutrophils, many eosinophils, renal tubular epithelial cells, and Kupffer cells. Hair shafts of the calves showed irregular distribution and clumping of melanin granules. Severe infection and a possible hemorrhagic tendency were recognized. These Brangus calves represent the third breed of cattle affected with this genetic disease.     

Evidence of existence of infectious hypodermal and hematopoietic necrosis virus in penaeid shrimp cultured in China

Infectious hypodermal and hematopoietic necrosis virus is the causative agent of a shrimp disease which causes economic losses on a global scale. A pair of primers, I2814F/I3516R, was designed from the IHHNV genomic sequence (GenBank) that encodes for structural protein corresponding to nucleotides 2814-3516, which amplifies a 703 base pair (bp) region from the virus genome. PCR amplification with the primers generated a product of the expected size from the purified IHHNV DNA of Litopenaeus vannamei and IHHNV-infected penaeid populations but not from the IHHNV-free shrimp, white spot syndrome virus (WSSV) and hepatopancreatic parvovirus (HPV). The PCR amplicon described above was labeled with digoxigenin (DIG)-11-dUTP as a probe used for dot blot hybridization and in situ hybridization test. Under the optimized PCR conditions, the primers were detected by as little as 20 fg of purified IHHNV DNA, which contained only 8.83 x 10(3) copies of IHHNV, a 1000-fold greater than using dot blot hybridization. Sections of histopathology showed eosinophilic intranuclear inclusions (Cowdry type A inclusions or CAIs) in infected tissues while in situ hybridization, cells displayed an intense reaction with the DIG-labeled probe. PCR assay was developed to detect IHHNV in penaeid shrimp and other crustaceans from the rearing ponds of China (March 2001-June 2004). The positive rate was 51.5% (154 out of 299) and 8.3% (2 out of 24) for penaeid shrimp and crab samples, respectively. The survey demonstrated the presence of IHHNV in China.     

Unique Physicochemical Properties of the Occluded Penaeid Shrimp Baculoviruses and Their Use in Diagnosis of Infections

Abstract

Occlusion bodies in wet mounts of phloxine-stained tissue squashes and paraffin sections of penaeid shrimp infected with Baculovirus penaei and Penaeus monodon-type baculovirus fluoresced when viewed with an epifluorescent microscope. Inclusions of hepatopancreatic parvo-like virus, infectious hypodermal and hematopoietic necrosis virus, and Autographa californica nuclear polyhedrosis virus did not fluoresce. The use of phloxine stain (alone or as a component of an eosin preparation) and fluorescent microscopy may enhance detection of lowgrade infections by these disease-causing agents.     

Thromboembolic meningocephalitis caused by Haemophilus somnus infection in a bull calf-a new disease in New Zealand

Thromboembolic meningoencephalitis (TEME) caused by Huemophilus somnus infection was diagnosed for the first time in New Zealand in an eight month old bull calf. Clinical signs included pyrexia, excessive salivation, recumbency, opisthotonus and rigidity of the front legs. Multiple red, malacic foci (1-10 mm in diameter) were visible grossly on the surface of the cerebrum and cerebellum, and were scattered throughout the brain parenchyma. Histologically these lesions consisted of focal haemorrhage, necrosis and neutrophilic infiltration. Fibrin thrombi and colonies of gram negative bacteria were present in many small blood vessels within necrotic foci. An organism with the morphological and biochemical characteristics of Haemophilus somnus was cultured from the brain. Although TEME is an important disease of feedlot cattle in North America and Europe it is relatively uncommon in cattle grazing pasture and is therefore unlikely to become a major problem in New Zealand.     

Cytologic diagnosis of Lawsonia intracellularis proliferative ileitis in a Japanese snow macaque (Macaca fuscata)

Diffuse ileal thickening and ileocecocolic lymphadenomegaly were observed during exploratory laparotomy in a 2-year-old male Japanese snow macaque (Macaca fuscata) that had flu-like signs and diarrhea. Cytologic examination of ileal biopsy imprints revealed many mature, mildly karyolytic neutrophils and fewer well-differentiated lymphocytes, eosinophils, macrophages, and plasma cells in a background containing amorphous, necrotic material. Tightly cohesive sheets of moderately pleomorphic epithelial cells also were seen. The cytologic diagnosis was chronic, active, mixed inflammation with atypical epithelial cells and necrosis. Histologically, the mucosal and crypt epithelium was moderately hyperplastic with a loss of goblet cells, increased mitoses, and frequent crypt abscesses. Within the lamina propria and extending into the submucosa was a marked neutrophilic infiltrate, with low numbers of lymphocytes, histiocytes, plasma cells, and eosinophils. The histologic diagnosis was chronic, diffuse, marked suppurative and lymphocytic ileitis. Warthin-Starry silver staining of the ileal biopsy and imprint specimens demonstrated numerous pleomorphic, curved bacilli consistent with Lawsonia intracellularis. Polymerase chain reaction (PCR) and immunohistochemistry confirmed the identity of the infectious agent. L intracellularis infection may be underdiagnosed because silver stain is required to visualize the organism with light microscopy and because the pathognomonic crypt hyperplasia may be complicated by secondary pathologic changes. Application of silver stain to cytologic specimens should be considered when distal intestinal lesions associated with hyperplastic epithelium, with or without inflammation, hemorrhage, or necrosis, are identified in animals with clinical signs of enteritis, especially in frequently affected species or in stressed or young animals.     

Experimentally induced parainfluenza type 3 virus infection in young lambs: pathologic response

Pulmonary changes in five 1-week-old, colostrum-deprived lambs transtracheally inoculated with parainfluenza type 3 virus were studied by immunofluorescent, microscopic, and ultrastructural techniques. The lambs were killed at postinoculation days (PID) 3, 5, and 7. Immunofluorescence specific for parainfluenza type 3 virus was first seen in small airways and alveolar epithelium and later in the lumens of airways and alveoli and, to a lesser extent, in the interstitium of the lungs. Grossly, there were multifocal areas of consolidation in all lobes of the lungs. These areas were characterized microscopically by bronchiolitis and interstitial pneumonitis. The bronchiolitis involved the terminal airways and consisted of necrosis and sloughing of epithelial cells followed by hyperplasia of the epithelium. The interstitial lesion comprised extensive infiltration of alveolar septa and alveoli with macrophages and the necrosis of alveolar epithelium. This was followed by hyperplasia of the epithelium. Degenerated bronchiolar and alveolar epithelium contained numerous intracytoplasmic inclusions early in the infection, but such inclusions were not seen in the lambs killed at PID 7. The degenerated changes were also seen with the electron microscope, as were numerous inclusions of viral nucleoprotein and a few viral buds at PID 3 and 5. Viral inclusions and buds were seen in ciliated and nonciliated bronchial epithelial cells and type I and type II alveolar epithelial cells.     

Sarcocystis encephalitis in a cockatiel

A sporozoan organism was considered to be the causative agent of central nervous system disease in a cockatiel. The ultrastructural characteristics were typical of the coccidian group Apicomplexa, and the fact that organisms were free within the cytoplasm of infected cells and not within a vacuole, indicated they were Sarcocystis. Light and electron microscopic evaluation of brain tissue demonstrated protozoal organisms associated with areas of necrosis. Differential diagnosis of central nervous system disease in pet birds should include protozoal encephalitis.     

对虾白斑综合症病毒变性高效液相色谱检测方法的建立与应用

据对虾白斑综合症病毒(WSSV)的基因保守序列,使用Primer Explorer V3软件设计了2条引物,利用PCR的扩增产物,结合变性高效液相色谱(DHPLC)技术,建立了一种对虾白斑综合症病毒的DHPLC快速检测方法。该检测方法特异性好,与传染性皮下和造血器官坏死病毒、斑节对虾杆状病毒、肝胰腺细小病毒、对虾杆状病毒以及对虾基因组DNA无交叉反应;检测灵敏度较高,约为10-5ng/μL,高于常规PCR及荧光定量PCR的灵敏度。用建立的DHPLC方法对100尾对虾样品进行了临床检测,结果与荧光定量PCR检测结果一致。WSSV的DHPLC检测方法,特异性强、灵敏度高,是对WSSV进行有效检测的一种新方法。     

Ochratoxin A and citrinin induced nephrosis in Beagle dogs. III. Terminal renal ultrastructural alterations

The extent and type of renal ultrastructural changes in Beagle dogs varied with the administration of ochratoxin A and citrinin alone and in the two dosage combinations. The three predominant changes were cytoplasmic vacuolation, myelin figure formation and lesions designated as cytoplasmic disarray. These changes were mainly of the endomembane system of the tubular epithelial cells. Cytoplasmic vacuoles were within proximal and distal tubules and collecting ducts and were most numerous in dogs given 10 mg/kg critrinin. Vacuolation of similar distribution, but less severe, was seen in renal tubular cells of dogs given the higher dose of the combined mycotoxins (0.2 mg/kg ochratoxin A + 10 mg/kg citrinin). This damage was limited to the proximal tubular cells in dogs given only ochratoxin A (0.1 or 0.2 mg/kg). Myelin figures were in proximal epithelial cells of dogs given ochratoxin A alone or combined with citrinin. There was cytoplasmic disarray in dogs of all groups except for dogs given 5 mg/kg citrinin. This lesions was usually limited to the proximal tubules. The lesions, however, was found in cells of the distal tubules of dogs given 10 mg/kg citrinin alone.     

Epitheliocystis disease in cultured pacu (Piaractus mesopotamicus) in Brazil.

Epitheliocystis disease was diagnosed in a cultured pacu (Piaractus mesopotamicus Holmberg, 1893) stock on the basis of gross pathological (greyish-white, pinpoint- or pinhead-sized focal areas, connected strongly to the gill lamellae) and histopathological examinations (hypertrophic cells 10-40 microns in size, having a well-defined wall and a central inclusion or characteristic granular content stained with Giemsa). The disease did not occur among fishes (Cyprinus carpio L., Ctenopharyngodon idella Cuv. and Val., Sarotherodon mosambicus Peters, Hoplias malabaricus Bloch) kept together with the affected pacus. About 30-40% of the pacu stock succumbed. Since branchial lesions and heavy mortality were observed in this pacu population, the aetiological role of the epitheliocystis agent could be suspected. Based upon ultrastructural examinations this agent is considered to be a chlamydia or a chlamydia-like organism.     

The emergence of Clostridium difficile as a pathogen of food animals

Clostridium difficile causes pseudomembranous colitis in humans, usually after disruption of the bowel flora by antibiotic therapy. Factors mediating the frank disease include the dose and toxigenicity of the colonizing strain, its ability to adhere to colonic epithelium, the concurrent presence of organisms that affect multiplication and toxin production or activity, and the susceptibility of the host. Toxins A (an enterotoxin) and B (a cytotoxin) play the major role in pathogenesis and the detection of toxins in gut contents is the gold standard for diagnosis. Disease in horses takes the form of often-fatal foal hemorrhagic enteritis. Nosocomial, antibiotic-associated, disease is increasingly common in adult horses. Enteric clinical signs are reported in ostriches, companion animals and recently calves. Clostridium difficile colitis is now a common diagnosis in neonatal pigs in the USA and elsewhere. Clinical features include onset at 1-5 days of age, sometimes with dyspnea, mild abdominal distension and scrotal edema, and commonly with yellow, pasty diarrhea. There is mesocolonic edema grossly, with microscopic diffuse colitis, mucosal edema, crypt distension, epithelial necrosis and superficial mucosal erosion. Neutrophil infiltration of the lamina propria is common, and fibrin and numerous rod-shaped bacteria are observed on the surface. About two-thirds of litters and one-third of piglets will be affected (based upon positive toxin tests), although this appears to vary with the season. The case fatality rate is probably low if considering only direct effects of C. difficile infection. The significance of toxin-positive non-diarrheic pigs and the nature of the interaction of toxins A and B with enterocytes are unknown. Given the widespread occurrence of the disease, there is substantial effort to develop immunoprophylactic products.     

Lythrum hyssopifolia (lesser loosestrife) poisoning of sheep in Victoria

Objective To document an ovine disease attributed to the consumption of Lythrum hyssopifolia (lesser loosestrife). Procedures Historical and histological review of field and experimental cases. Results 1–20% mortality occurred in sheep flocks grazing paddocks where L. hyssopifolia was the predominant green vegetation. Well‐documented disease outbreaks occurred in summer on nine farms across Victoria between 1974 and 2002. Liver damage occurred in all nine outbreaks, with kidney damage in at least eight. Hepatocyte necrosis was usually zonal to midzonal (zone 2) in the liver samples from four farms and periacinar (zone 3) in those from three farms, but some livers showed only single‐cell necrosis. Multinucleate hepatocytes near necrotic areas were a feature in six cases. Proximal tubular epithelium appeared to be the primary renal target and brown granules were often present in renal tubules. Biochemical and histological evidence of liver and kidney damage was obtained from two sheep experimentally pen‐fed harvested L. hyssopifolia. Conclusion Chemicals in L. hyssopifolia are toxic to ovine hepatocytes and renal tubular epithelial cells.     

Prevalence and causes of ram epididymitis in Utah

Palpation of the testicles and epididymides was used to determine the prevalence of ram epididymitis (RE) in Utah range flocks over a 5-year period. Of 62 range flocks examined, 58 had rams with palpable lesions. A comparison was made of prevalence by right vs left testicle involvement, but no significant difference was found. Culling all rams with palpable lesions from the flock progressively reduced the annual incidence, but did not eliminate RE from any flock. Semen and specimens of reproductive tract tissue were obtained from representative flocks for bacterial culture. Brucella ovis was found commonly in range flocks, but was not isolated from RE-affected rams in virgin, ram-producing flocks. In the ram-producing flocks, a gram-negative, pleomorphic rod-type organism was found. It was concluded that RE should be considered as 2 disease entities, based on the finding of 2 causative organisms and the management systems under which those organisms are found. Brucella ovis was the major cause in persistently infected range flocks, whereas the gram-negative pleomorphic rod-type organism is the apparent cause of RE in virgin, ram-producing flocks.     

Escherichia coli associated endotoxemia in dogs with parvovirus infection

Escherichia coli bacteremia and endotoxemia were observed in 3 adult mongrel dogs which had been prediagnosed as canine parvoviral disease. The endotoxin level was 46.5 pg/ml in the plasma of clinical cases, while 2.3 pg/ml in healthy controls. The microflora of the feces was confused in the clinical cases. The percentage of E. coli was major in the feces. Serologically similar strains were isolated from the blood. These strains did not produce enterotoxins such as heat-stable enterotoxin (ST) and heat-labile enterotoxin (LT). Histopathologically, the lesions in the small intestine consisted of epithelial degeneration and necrosis. Viral inclusion bodies were frequently observed in the epithelial cells. Disseminated intravascular coagulation was observed in various tissues including the liver and small intestinal submucosa. After experimental infection with CPV, all dogs showed various clinical signs. CPV was positive in the feces. Endotoxin level in the plasma gradually increased and high level continued for long period from 10 to 30 days. Mean maximum level of endotoxin in the experimental dogs was 73.6 pg/ml. These results indicate that intestinal flora plays a important role in the pathogenesis of CPV infection and that endotoxin is one of the factors which predispose to severe disease after the infection.     

Gastric spirillosis in beagles

Light microscopic, ultrastructural, and microbiologic evaluations were performed on stomachs from 30 healthy laboratory-reared Beagles. Spiral-shaped microorganisms were seen in the gastric glands and parietal cell canaliculi of all the dogs. Organisms were most numerous in the cardia and in the region of the fundic-pyloric junction. Lymphoreticular hyperplasia, dilatation of parietal cell canaliculi, and degeneration of individual parietal cells (rarely seen) were the only morphologic alterations seen. Organisms were helical, had tufts of flagella at each end, and were approximately 0.5 X 7.0 micron; some had a distinct axial fibril (indicating two distinct forms of the organism). Attempts to propagate a viable culture of the organism were not successful. The organism most closely resembled those of the genus Spirillum. Because the organism was commonly found in the gastric mucosa of healthy Beagles, it probably should be considered part of the natural gastric flora of dogs.     

光合细菌对动物的营养作用及对动物疾病的防治作用

光合细菌是一类有益的微生物,它在动物的营养及疾病防治方面可以发挥重要作用。本文综述了我们试验的光合细菌对家畜动物如牛、猪、羊、肉狗、兔的增重和水产动物如淡水鱼、对虾的增产作用,对哺乳期动物的采食和泌乳的影响及对动物疾病尤其是胃肠道疾病的防治作用。光合细菌可以作为一种优质安全的营养保健型饲料添加剂进行推广,预计可具有可观的经济效益和社会效益。     

Pasteurella multocida infection in Japanese quail (Coturnix coturnix japonica)

Three flocks of Japanese quail, approximately 75,000 birds each, experienced acute high mortality beginning at 24 to 28 days of age. Gross lesions were absent or were composed of either multifocal small pale areas on livers and spleens or lungs slightly darker in color than normal. Histopathology revealed multifocal splenic and hepatic necrosis and interstitial pneumonia. Pasteurella multocida, serotype 3,4, was isolated from affected tissues. The quail were successfully treated with chlortetracycline, and the organism was apparently eliminated from the premises by thorough cleaning, disinfection, and insect and rodent control. Experimental studies showed Japanese quail to be highly susceptible to disease caused by the P. multocida isolated from the affected flocks.