The outbreak of chlamydiosis in one of the western provinces of Poland, was diagnosed accidentally as a concurrent infection in a commercial laying hen flock during an outbreak of fowl pox. For histological examination, skin and subcutaneous tissue samples from lesions on heads of the birds were collected. Swabs from throat and trachea have been examined by nested PCR, real-time PCR, and partial ompA sequencing. Detailed electron microscopy analysis revealed fowl pox intracytoplasmic inclusions, called Bollinger bodies, and the presence of other intracytoplasmic inclusions; specific for Chlamydia sp. Results of nested PCR confirmed the presence of Chlamydiaceae sp. in two tested samples. Surprisingly, one of the two Chlamydiaceae-positive cases turned out to be infected with a non-classified strain. Results of real-time PCR and sequencing confirmed the presence of a new Chlamydia species that has not been found in Poland to date. Partial sequencing and BLAST analysis of ompA gene sequence confirmed the highest homology to non-classified poultry strains of Chlamydia sp. that were previously detected in Germany and France. The zoonotic potential and the exact taxonomic status of this atypical strain have yet to be defined.

Introduction: There is still lack of morphological and phylogenetic information on the pathogenic nematode of the camel Haemonchus longistipes. In the present study, this parasite was isolated in Saudi Arabia and described. Material and Methods: The abomasa of two Arabian camels were collected from a slaughterhouse in Abha province and examined for nematode infection. Worms were described morphologically and morphometrically by electron microscopy. Multiple sequence alignment and the phylogenetic tree of the parasite were constructed from maximum likelihood analysis of its ITS-2 rDNA sequences. Results: These nematodes had a slender body terminating anteriorly at a conspicuous dorsal lancet. A pair of lateral cervical papillae distant from the anterior end was observed. The buccal aperture was hexagonal and surrounded by two amphids, six externo-labial papillae, and four cephalic papillae. Males terminated posteriorly at a bursa supported by spicules and lateral and dorsal rays. Females were linguiform and knobbed morphotypes with distinct ovijectors and a dorsal rim covering the anal pore. The taxonomy was confirmed by the morphology and number of the longitudinal cuticular ridges in a 43–46 range. The sequence alignment and phylogeny revealed 92% homology with H. longistipes (AJ577461.1), and the sequence was deposited into GenBank. Conclusion: The present study describes H. longistipes morphologically and molecularly which facilitates further discrimination of this species worldwide.

Two cytopathic agents were isolated on porcine alveolar macrophages following inoculation with homogenates of lung tissues from pigs showing respiratory problems. These isolates were identified as porcine reproductive and respiratory syndrome (PRRS) virus isolates by indirect immunofluorescence using a PRRS virus (PRRSV) specific monoclonal antibody (MAb) and were designated as LHVA-92-1 and LHVA-92-2. Immunogold electron microscopy using a porcine PRRS positive serum pool and protein A-gold resulted in an intense labelling of aggregates of viral particles. Dark specific cytoplasmic staining of porcine alveolar macrophages infected with both virus isolates could be observed by immunogold silver staining (IGSS) using the specific MAb. This method proved effective in detecting PRRSV antigens in several ethanol-fixed tissues of piglets intranasally inoculated with the supernatants of macrophages infected with each isolate. Immunogold silver staining was also successfully used for the detection of PRRSV antigens on sections of formalin-fixed paraffin-embedded lung tissues and on frozen sections of lungs. The present results indicate that colloidal gold may be useful for the identification and immunohistochemical detection of PRRSV in tissues.

A double-antibody ELISA for the detection of coronaviruses in intestinal contents from turkey poults with diarrhea was developed. Antibodies were raised in rabbits and guinea pigs against a Minnesota isolate of turkey enteric coronavirus (TCV) propagated in embryonating turkey eggs and were purified by density-gradient centrifugation. The specificity of antisera was confirmed by hemagglutination-inhibition and immunoelectron microscopy. Absorption of anti-TCV hyperimmune sera with egg extracts or egg ovalbumin and the use of different dilution and blocking buffers influenced the sensitivity and specificity of the ELISA. Reciprocal cross-reactivity was detected among turkey, chicken, bovine, and murine coronaviruses. Antisera to the transmissible gastroenteritis virus of swine, the rabbit enteric coronavirus, or the human coronavirus strain 299E failed to react with TCV. The TCV cross-related only moderately with the avian infectious bronchitis virus and the hemagglutinating encephalomyelitis virus of swine. Investigations with samples from 47 commercial turkey flocks in Quebec with episodes of transmissible enteritis revealed that the ELISA was more sensitive than was electron microscopy for dectection of TCV.

Electron microscopy revealed several unique features in canine bone marrow, compared with that of other species. The marrow was fatty and extensively trabeculated and was enclosed by a complete layer of endosteal bone-lining cells. Branched reticular cells were closely associated with each other and, occasionally covered part of the sinus wall as an adventitial layer. The extent of adventitial coverage varied markedly and was less extensive, compared with that of other species. On average, only 23% of the sinus wall was covered by adventitial layer, in contrast to 65% reported in laboratory animals. Unilaminar sinuses, with no adventitial coverage, accounted for greater than 38% of all sinuses. Quantitative analysis indicated that 60% of the latter sinuses contained apertures, as opposed to 35% of sinuses with adventitial coverage (P less than 0.05). Moreover, the number of apertures in unilaminar sinuses was significantly (P less than 0.009) greater than that in multilaminar sinuses. Apertures were observed every 59 micromoles in unilaminar sinuses, in contrast to every 109 micromoles in multilaminar sinuses. Approximately 75% of the apertures were occupied by cells in transit, and only 25% were free of cells. Macrophages were distributed throughout the marrow and were closely associated with all blood cell lines. Occasionally, cells that entered the lumen were not fully mature. Erythroblasts were seen migrating across the wall and within the lumen of sinuses. The less-extensive adventitial coverage in canine bone marrow might indicate that the rate of cell delivery from the marrow into the circulation was relatively high in this species. The prevalence of unilaminar sinuses, along with the larger number of apertures, suggested that these sinuses were more accessible to the migrating cells and that the cellular traffic across them was intense.

Streptococcus suis is an important swine pathogen and a zoonotic agent causing meningitis and septicemia. Although serotype 2 is the most virulent type, serotype 14 is emerging, and understanding of its pathogenesis is limited. To study the role of the capsular polysaccharide (CPS) of serotype 14 as a virulence factor, we constructed knockout mutants devoid of either cps14B, a highly conserved regulatory gene, or neu14C, a gene coding for uridine diphospho-N-acetylglucosamine 2-epimerase, which is involved in sialic acid synthesis. The mutants showed total loss of the CPS with coagglutination assays and electron microscopy. Phagocytosis assays showed high susceptibility of mutant Δcps14B. An in vivo murine model was used to demonstrate attenuated virulence of this non-encapsulated mutant. Despite the difference in the CPS composition of different serotypes, this study has demonstrated for the first time that the CPS of a serotype other than 2 is also an important antiphagocytic factor and a critical virulence factor.

When large numbers of crocodile skins were downgraded because of the presence of small pin pricklike holes, collapsed epidermal cysts were found deep in the dermis of juvenile crocodiles while forming cysts were observed in hatchlings. Histopathology of these forming cysts showed the presence of intracytoplasmic inclusions in proliferating and ballooning epidermal cells. Pox virions were seen in electron microscope preparations made from the scabs of such early lesions. The partial sequencing of virus material from scrapings of these lesions and comparison of it with the published sequence of crocodile poxvirus showed the virus associated with the deep lesions to be closely related, but different. To differentiate between the two forms of crocodile pox infection it is suggested that the previously known form should be called "classical crocodile pox" and the newly discovered form "atypical crocodile pox". The application of strict hygiene measures brought about a decline in the percentage of downgraded skins.

Eighteen strains of Escherichia coli serogroup O115:K"V165" isolated from 1- to 8-week-old pigs with diarrhea were tested for toxigenicity, pathogenicity in pigs and mice, serum resistance, mannose-resistant hemagglutination (MRHA), F165 and other surface antigens, colicin V (Col V), aerobactin, and biotype. Twelve strains were positive for heat-stable enterotoxin (STb), MRHA-negative, and F165-negative; 5 strains were enterotoxin-negative, MRHA-positive, and F165-positive; and 1 strain was MRHA-positive, but F165- and enterotoxin-negative. Six of the 12 STb-positive strains moderately colonized the ileum of newborn colostrum-deprived pigs within 24 hours after inoculation. Two of the colonizing strains were able to induce watery diarrhea. All 12 STb-positive strains were nonpathogenic for adult mice and were serum-sensitive; 11 of 12 were Col V-negative, 9 of 12 did not produce aerobactin, and 10 of 12 belonged to biotypes other than 1 or 2. All 6 enterotoxin-negative strains colonized the small and large intestines, associated with peritoneal serosal surfaces, and induced septicemia and polyserositis in newborn colostrum-deprived pigs 1 to 2 days after inoculation. In contrast, 3 STb-positive strains poorly colonized the intestines and did not induce septicemia in pigs at 3 days after inoculation. All 6 enterotoxin-negative strains were Col V-positive, produced aerobactin, and belonged to biotype 1 or 2. Of the 5 enterotoxin-negative, F165-positive strains, only 4 were pathogenic for intraperitoneally inoculated adult mice and were serum-resistant. The enterotoxin-negative, F165-negative strain was neither serum-resistant nor mouse-pathogenic. O-agglutinable mutants of the mouse-pathogenic strains were, for the most part, no longer pathogenic for adult mice, although these strains remained unchanged for biotype and production of MRHA, F165, and Col V, and 3 of 4 mutant strains were serum-resistant. Thus, E coli strains of the same serogroup isolated from diarrheic pigs may cause either intestinal or extraintestinal disease upon reinoculation of pigs, depending on the virulence attributes produced by the strains.

The lung is a complex organ, and its physiology and immunology are regulated by various immune molecules and cells. Lung surfactant, a mixture of phospholipids and proteins produced by the bronchiolar and type II alveolar epithelial cells, is one such important player in lung physiology. Compared to knowledge about the biology of the surfactant in rodents and humans, only limited data are available on the surfactant in the horse. Although there are data linking levels of surfactant proteins with respiratory disease in the horse, there are no data on the cellular localization of surfactant protein A (SP-A) and surfactant protein D (SP-D). A member of the tetraspanin family of proteins, CD9 is a cell-signaling and adhesion protein and its expression has been detected in both normal and cancer cells, including those in the lung. Because there are no immunolocalization data on SP-A, SP-D, and CD9 in the normal lungs of the horse, our objective was to conduct a light and electron microscopic immunocytochemical study on normal lungs of the horse. The data showed SP-A and SP-D in bronchiolar epithelial and type II alveolar epithelial cells. These proteins were also localized in type I alveolar epithelial cells, pulmonary intravascular macrophages, and neutrophils, which is likely an outcome of endocytosis of the proteins by these cells. CD9 was present in the airway and vascular smooth muscle cells, endothelium, and blood cells, but not in the airway epithelium. These new data provide a baseline to further examine the expression and functions of SP-A, SP-D, and CD9 proteins in inflammation associated with respiratory diseases in the horse.

Retinoids play an important role in lung development and immune response. The effects of retinoids are mediated through 2 families of retinoid receptors: retinoic acid receptors (RARs) and retinoid X receptors (RXRs), with alpha (α), beta (β), and gamma (γ) subtypes in each family. To date, no data exist on the expression pattern of retinoid receptors in lungs of cattle, dogs, and pigs. Because of the biomedical importance of retinoid receptors in inflammation and immune responses, Western blot, immunohistology, and immunoelectron microscopy were used to determine the expression of retinoid receptors in normal lungs of cattle, dogs, and pigs (n = 2 for each species). Western blot showed expression of all 6 retinoid receptor subtypes in pig lungs. Immunohistology data indicated differential expression of retinoid receptors in airway epithelium, vascular endothelium, alveolar/septal macrophages, and alveolar septum in all 3 species. Electron microscopy showed nuclear localization of retinoid receptors in neutrophils and pulmonary intravascular macrophages. Retinoic acid receptors (RAR) α subtype were localized in cytoplasmic vacuoles of pig monocytes. These data indicate constitutive expression of retinoid receptors in the lungs of cattle, dogs, and pigs.