Heligmosomoides polygyrus and Trypanosoma congolense infections in mice: effect of immunisation by abbreviated larval infection.

Concurrent African trypanosome and gastrointestinal helminth infections are prevalent in sub-humid savannah where they are endemic. However, acquired resistance in animals varies with their responder status and exposure. As a guide to study in the definitive hosts, the effects of Trypanosoma congolense infection on the development and maintenance of homologous Heligmosomoides polygyrus resistance were investigated in outbred TO mice. These mice were immunised by abbreviation of larval infection. Immune or naive mice were either infected with 500 infective larvae (L3) of H. polygyrus and/or 10(4) bloodstream forms of T. congolense or were not infected. The outcome of infection was monitored by routine parasitological and immunological techniques for 30 days after the day of the T. congolense infection. Significantly more immune mice concurrently infected with both parasites survived than did immune mice in which H. polygyrus was superimposed on a 10-day-old T. congolense infection. Although all the mice in this latter group died before the end of the experiment, larval immunisation prolonged their survival, relative to similarly treated naive mice. The antibody titres to H. polygyrus in the sera of immune mice challenged with H. polygyrus alone were significantly higher than those of immune mice concurrently infected with both parasites but the levels of protection obtained were comparable. It is concluded that T. congolense may not completely block the strong acquired resistance induced by abbreviated H. polygyrus larval infection in TO mice but is capable of interfering with protective responses, especially if the trypanosome infection occurs prior to H. polygyrus challenge infection.     

Regulation of DNA synthesis in Leydig cells obtained from neonatal pig testes.

Three distinct waves of Leydig cell development are found in the pig testes, which occur during fetal, perinatal, and prepubertal periods. Proliferation of Leydig cells is primarily regulated by luteinizing hormone (LH); however, effects of LH on proliferation of immature rat Leydig cells are mediated by specific growth factors and cytokines such as transforming growth factor-alpha (TGFalpha), insulin-like growth factor-1 (IGF-1), interleukin-1beta (IL-1beta), steroidogenesis-inducing protein (SIP), and TGFbeta. The objective of the present study was to identify growth factors that could possibly be involved in the proliferation of Leydig cells in the neonatal pig testis. Leydig cells were isolated from 3- to 5-d-old pig testes, cultured for 48 hr in serum-free media, washed, and treated with hCG and/or IGF-1, epidermal growth factor (EGF), IL-1beta, SIP, and TGFbeta for 18 hr. Tritiated thymidine incorporation into DNA was assessed over a subsequent 4-hr period. Incorporation of [3H]-thymidine was stimulated by hCG treatment with a 2.3-fold increase over control cultures. SIP also induced a significant increase (P < 0.0001) in the incorporation of [3H]thymidine into Leydig cell DNA. Similarly, EGF and IGF-1 also increased DNA synthesis in neonatal porcine Leydig cells, whereas IL-1beta had no effect. TGFbeta had very little, if any, effect on DNA synthesis when added alone, but inhibited the stimulatory effects of other mitogens (SIP, hCG, EGF/TGFalpha, and IGF-1). Our results indicate that these growth factors may play a role in the LH/hCG-dependent proliferation of Leydig cells during the perinatal period of development.     

Ultrastructure of porcine circovirus in persistently infected PK-15 cells.

The ultrastructure of porcine circovirus was examined in persistently infected porcine kidney (PK)-15 cells. Virus-infected PK-15 cells had large numbers of intracytoplasmic inclusions, and a few cells had intranuclear inclusions. Intracytoplasmic inclusions were dispersed throughout the cytoplasm but were most numerous in the perinuclear cytoplasm. Inclusion were of various sizes, round to oval, and electron dense and were of two general types. Inclusions of the first type were small (0.1-0.5 microm diameter), not surrounded by trilaminar membranes, and granular with indistinct margins that blended with surrounding cytoplasm. Some contained 12+/-2-nm-diameter icosahedral virions in loose aggregates or rarely forming paracrystalline arrays. Small inclusions could be sites of viral assembly or maturation. Intracytoplasmic inclusions of the second type were larger (0.5-5.0 microm diameter) and more numerous and had abrupt margins surrounded by trilaminar membranes. They were more electron dense than small inclusions and were heterogeneous, containing various proportions of aggregated virions, electron-dense crystalline lamellae of 5 nm periodicity, and/or whorls of myelinoid membranes. Virions usually formed paracrystalline arrays and occasionally were loosely aggregated. Larger inclusions were typical of autophagolysosomes. Intranuclear inclusions were not membrane bound and were often associated with reticulated nucleoli or aggregates of heterochromatin. Some inclusions were irregularly shaped aggregates of indistinct, circular 10-12-nm-diameter viruslike particles. Others were 0.1-1.0 microm in diameter, round or ring shaped, dense, and finely granular, with sharply demarcated margins.     

Survival of Salmonella in the crop contents of market-age broilers during feed withdrawal.

Recent studies have indicated that crop contamination increases during preslaughter feed withdrawal and that contaminated crop contents may serve as an important source of Salmonella entry into poultry processing plants. During the present study, we evaluated the effect of preslaughter feed withdrawal on crop pH and Salmonella crop contamination in broilers from three commercial broiler flocks. The effect of experimental feed withdrawal on crop pH, lactic acid concentration, and Salmonella crop contamination was also evaluated in market-age broilers challenged experimentally with Salmonella typhimurium. Crop pH increased significantly (P < 0.05) from 3.64 +/- 0.25 before feed removal to 5.14 +/- 0.72 after 8 hr of feed withdrawal in broilers from commercial flocks. The incidence of Salmonella crop contamination in the commercial broilers increased (P < 0.05) from 3.3% before feed removal to 12.6% after 8 hr of feed withdrawal. Similarly, crop pH increased (P < 0.05) by a magnitude of approximately 1 unit in broilers after 8 hr of experimental feed withdrawal. The population of S. typhimurium in the crops of the experimentally challenged broilers increased (P < 0.05) by approximately 1 log unit during the 8-hr experimental feed withdrawal. The concentration of lactic acid in the crop of the broilers during experimental feed withdrawal decreased (P < 0.01) from a range of 119-135 mumol/ml before feed removal to a range of 22-32 mumol/ml after 8 hr of feed withdrawal. The results indicated that feed withdrawal resulted in a decrease in lactic acid in the crop, accompanied by an increase in crop pH, and an increase in Salmonella crop contamination.     

Interbreed variation of DLA-DRB1, DQA1 alleles and haplotypes in the dog.

Although 36 DLA-DRB1 and 10 DLA-DQA1 allele sequences have been published to date, no data on individual allele frequencies exists, either for specific breeds or cross breeds, and the full extent of the polymorphism at each of these loci is still not known. We have used sequence-specific oligonucleotide probing (SSOP) to characterise a series of 367 dogs for their DRB1 and DQA1 alleles. These included individual animals from over 60 different breeds, with numbers per breed ranging from 1 to 39. DLA types were generated from 218 dogs for DRB1 and from 330 dogs for DQA1, while 181 dogs were characterised for both these loci. The frequency of individual DRB1 and DQA1 alleles showed considerable interbreed variation, e.g. 83% of West Highland White Terriers were DRB1*01 as opposed to 9% of Collies. No breed had >9 of the 22 DRB1 types defined in this study; several breeds had only two DRB1 types. DLA-DQA1 showed less variation in allele numbers per breed, but also showed considerable interbreed frequency variation. Haplotype analysis revealed over 44 different DRB1/DQA1 combinations. Of these, 25 were in a number of animals, and also in an animal that was homozygous for one or both of these loci. Some DRB1 alleles could be found in combination with several different DQA1 alleles, while others were only present in one haplotypic combination. DLA allele frequency data in normal dogs will be critical for disease association studies. It may also be possible to use haplotype data to establish the genetic relationships between different dog breeds.     

Evaluation of iodophor skin preparation techniques and factors influencing drainage from ventral midline incisions in horses.

OBJECTIVE: To document natural bacterial flora on the ventral aspect of the equine abdomen, to compare 2 preparation techniques, and to identify potential risk factors that may contribute to incisional drainage. DESIGN: Prospective study. ANIMALS: 53 horses undergoing exploratory celiotomy. PROCEDURE: Group-1 horses (n = 26) were prepared with povidone-iodine and alcohol. Group-2 horses (27) were prepared with a film-forming iodophor complex. Numbers of bacterial colony-forming units (CFU) were measured before and after surgical scrub, following skin closure, and after recovery from general anesthesia. Swab specimens to identify normal skin bacterial flora and potential pathogens were obtained by swabbing a 4 x 4-cm area. Variables that might affect incisional drainage were also investigated. RESULTS: For both techniques, there was a significant reduction in bacterial numbers after skin preparation. Incisional drainage was observed in 14 (26%) horses (8 group-1 and 6 group-2 horses). Preexisting dermatitis, poor intraoperative drape adherence, high number of bacterial CFU obtained after recovery from anesthesia, and high number of CFU obtained from the surgery room environment were the main risk factors associated with subsequent incisional drainage. Bacillus spp, nonhemolytic Staphylococcus spp, Micrococcus spp, Corynebacterium spp, Streptomyces spp, other nonenteric genera, and nonhemolytic Streptococcus spp were the most common isolates obtained before surgical scrub. CONCLUSIONS AND CLINICAL RELEVANCE: Both skin preparation techniques were equally effective in reducing numbers of bacterial CFU by 99%, and a significant difference was not found in incisional drainage rate between groups. Protection of the wound during recovery from anesthesia and the immediate postoperative period may reduce incisional drainage after abdominal surgery in horses.     

Coccygeal muscle injury in English Pointers (limber tail)

A condition colloquially referred to as "limber tail" and "cold tail" is familiar to people working with hunting dogs, primarily Pointers and Labrador Retrievers. The typical case consists of an adult dog that suddenly develops a flaccid tail. The tail either hangs down from the tail base or is held out horizontally for several inches from the tail base and then hangs straight down or at some degree below horizontal. Initially, the hair on the dorsal aspect of the proximal tail may be raised and dogs may resent palpation of the area 3-4 inches (8-10 cm) from the tail base. Most dogs recover spontaneously within a few days to weeks. Anecdotal reports suggest that anti-inflammatory drugs administered within 24 hours after onset hasten recovery. Less than one half of affected dogs experience a recurrence. Affected Pointers almost always have a history of prolonged cage transport, a hard workout the previous day, or exposure to cold or wet weather Most owners and trainers familiar with the condition do not seek veterinary assistance. In cases where people are not familiar with this disease, other conditions such as a fracture, spinal cord disease, impacted anal glands, or prostatic disease have been incorrectly diagnosed. We examined 4 affected Pointers and found evidence of coccygeal muscle damage, which included mild elevation of creatine kinase early after onset of clinical signs, needle electromyographic examination showing abnormal spontaneous discharges restricted to the coccygeal muscles several days after onset, and histopathologic evidence of muscle fiber damage. Specific muscle groups, namely the laterally positioned intertransversarius ventralis caudalis muscles, were affected most severely. Abnormal findings on thermography and scintigraphy further supported the diagnosis.     

Analysis of the mucosal microenvironment: factors determining successful responses to mucosal vaccines

The predominance of IgA antibodies in mucosal sites reflects a combination of high rate IgA isotype switching among precursor cells in induction sites, their selective localisation in mucosal effector tissues and vigorous proliferation of these cells after extravasation. Each of these steps leading to IgA expression at the mucosa is under cytokine control. This paper will address the role of cytokines in induction and expression of IgA responses, the contribution of various precursor cell subsets and their differential responses to cytokine signals and strategies for manipulating cytokine expression. With respect to IgA antibody production in the gut whereas IL-4 and TGF-beta have been implicated in isotype switching of precursor cells to IgA commitment, their subsequent localisation, proliferation and effector activity expression is dependent on IL-5 and IL-6 expression locally. Most IgA plasma cells in the intestine derive from cells of the B2 lineage in the Peyer's patch, but a subpopulation of cells derived from the peritoneal cavity (B1 cells) also contribute to the IgA plasma cell population in the intestinal lamina propria. Whereas IgA+ cells of the B2 lineage are IL-6 dependent but IL-5 independent, B1-derived IgA+ cells are IL-5 dependent and IL-6 independent. On the other hand, cell mediated immune responses in the gut are highly dependent on IFN-gamma production by both Th1 CD4 cells and CD8 cells and in enteric Salmonella infection IFN-gamma production is essential but antibody has little effect on this process.Therapeutic interventions based on the information emerging from these studies will lead to improved vaccination responses and correction of immunodeficiencies especially in young animals.     

A dermoid of the eye in a blue-fronted Amazon parrot (Amazona aestiva)

A corneo-conjunctival dermoid is reported in a blue-fronted Amazon parrot ( Amazona aestiva ). After laminar keratectomy, histology showed the epidermis with feather follicles and dermal connective tissue with lymph follicles and sebaceous glands.