Immune response to recombinant Escherichia coli Iss protein in poultry

Colibacillosis accounts for significant losses to the poultry industry, and control efforts are hampered by limited understanding of the mechanisms used by avian pathogenic Escherichia coli (APEC) to cause disease. We have found that the presence of the increased serum survival gene (iss) is strongly associated with APEC but not with commensal E. coli, making iss, and the protein it encodes (Iss), candidate targets of colibacillosis control procedures. To assess the potential of Iss to elicit a protective response in chickens against APEC challenge, Iss fusion proteins were produced and administered subcutaneously to four groups of 2-wk-old specific-pathogen-free leghorn chickens. At 4 wk postimmunization, birds were challenged with APEC from serogroups 02 and 078 via intramuscular injection. At 2 wk postchallenge, birds were necropsied, and lesions consistent with colibacillosis were scored. Also, sera were collected from the birds pre- and postimmunization, and antibody titers to Iss were determined. Immunized birds produced a humoral response to Iss, and they had significantly lower lesion scores than the unimmunized control birds following challenge with both APEC strains. Birds that received the smallest amount of immunogen had the lowest lesion scores. Although further study will be needed to confirm the value of Iss as an immunoprotective antigen, these preliminary data suggest that Iss may have the potential to elicit significant protection in birds against heterologous E. coli challenge.     

Cardiovascular dysfunction in dogs associated with critical illnesses

The records of 16 dogs with left ventricular dysfunction associated with severe systemic illness were reviewed. The most common diagnoses in affected dogs were sepsis and cancer. Despite left ventricular dysfunction, no dog presented with signs of congestive heart failure. Fifteen dogs were presented with generalized weakness as a part of their clinical complaint. Twelve (75%) of 16 dogs died or were euthanized within 15 days of admission to the hospital. The average time until death was 3.6 days.     

Recombinant Iss as a potential vaccine for avian colibacillosis

Avian pathogenic Escherichia coli (APEC) cause colibacillosis, a disease which is responsible for significant losses in poultry. Control of colibacillosis is problematic due to the restricted availability of relevant antimicrobial agents and to the frequent failure of vaccines to protect against the diverse range of APEC serogroups causing disease in birds. Previously, we reported that the increased serum survival gene (iss) is strongly associated with APEC strains, but not with fecal commensal E. coli in birds, making iss and the outer membrane protein it encodes (Iss) candidate targets for colibacillosis control procedures. Preliminary studies in birds showed that their immunization with Iss fusion proteins protected against challenge with two of the more-commonly occurring APEC serogroups (O2 and O78). Here, the potential of an Iss-based vaccine was further examined by assessing its effectiveness against an additional and widely occurring APEC serogroup (O1) and its ability to evoke both a serum and mucosal antibody response in immunized birds. In addition, tissues of selected birds were subjected to histopathologic examination in an effort to better characterize the protective response afforded by immunization with this vaccine. Iss fusion proteins were administered intramuscularly to four groups of 2-wk-old broiler chickens. At 2 wk postimmunization, chickens were challenged with APEC strains of the O1, O2, or O78 serogroups. One week after challenge, chickens were euthanatized, necropsied, any lesions consistent with colibacillosis were scored, and tissues from these birds were taken aseptically. Sera were collected pre-immunization, postimmunization, and post-challenge, and antibody titers to Iss were determined by enzyme-linked immunosorbent assay (ELISA). Also, air sac washings were collected to determine the mucosal antibody response to Iss by ELISA. During the observation period following challenge, 3/12 nonimmunized chickens, 1/12 chickens immunized with 10 microg of GST-Iss, and 1/12 chickens immunized with 50 microg of GST-Iss died when challenged with the O78 strain. No other deaths occurred. Immunized chickens produced a serum and mucosal antibody response to Iss and had significantly lower lesion scores than nonimmunized chickens following challenge, regardless of the challenge strain. This study expands on our previous report of the value of Iss as an immunoprotective antigen and demonstrates that immunization with Iss can provide significant protection of chickens against challenge with three different E. coli strains.     

A retrospective study of the clinical, histological, and immunohistochemical manifestations of 5 dogs originally diagnosed histologically as necrotizing scleritis

Purpose To describe the clinical, histological, and immunohistochemical manifestations of canine necrotizing scleritis. Methods A retrospective examination of the clinical records and samples of ocular tissues from five dogs with a histological diagnosis ‘necrotizing scleritis’ was completed. Archived, formalin‐fixed, paraffin‐embedded samples and two control globes were stained with hematoxylin and eosin, Gram, periodic acid–Schiff (PAS) and Masson trichrome stains, and they were immunohistochemically labeled for CD3, CD18, and CD20. Results Of the five cases reviewed, only two could be confirmed as idiopathic necrotizing scleritis. The other three cases were retrospectively diagnosed as unilateral focal, non‐necrotizing scleritis, one as episcleritis and the third was scleritis secondary to a proptosed globe based on our retrospective clinical, histological, and immunohistochemical evaluations. In these two cases, idiopathic necrotizing scleritis manifested as a bilateral, progressive, inflammatory disease of the sclera and cornea that induces significant uveitis. Light microscopic examination confirmed collagen degeneration and granulomatous inflammation. There was no evidence for an infectious etiology based on Gram’s and PAS stainings. Immunohistochemical labeling revealed a predominance of B cells in idiopathic, bilateral necrotizing scleritis. Tinctorial staining abnormalities with Masson’s trichrome stain were present in scleral collagen of the two cases with idiopathic necrotizing scleritis as well as a case of secondary traumatic scleritis. Conclusions Based on a limited number of cases, idiopathic canine necrotizing scleritis shares similar histopathological features with non‐necrotizing scleritis and episcleritis; however, necrotizing scleritis is B‐cell‐dominated and bilateral, and significant collagen alterations manifest with Masson’s trichrome stain.     

Clinical Anesthesia and Analgesia in Fish

Fish have become a popular experimental model and companion animal, and are also farmed and caught for food. Thus, surgical and invasive procedures in this animal group are common, and this review will focus on the anesthesia and analgesia of fish. A variety of anesthetic agents are commonly applied to fish via immersion. Correct dosing can result in effective anesthesia for acute procedures as well as loss of consciousness for surgical interventions. Dose and anesthetic agent vary between species of fish and are further confounded by a variety of physiological parameters (e.g., body weight, physiological stress) as well as environmental conditions (e.g., water temperature). Combination anesthesia, where 2 anesthetic agents are used, has been effective for fish but is not routinely used because of a lack of experimental validation. Analgesia is a relatively underexplored issue in regards to fish medicine. However, recent studies have investigated opioid agents, nonsteroidal antiinflammatory drugs, and local anesthetics to determine their efficacy in minimizing pain and discomfort. The opioid morphine and the local anesthetic lidocaine do have significant effectiveness in reducing pain-related responses in rainbow trout (Oncorhynchus mykiss). Studies aimed at developing reliable analgesic protocols should explore a wide range of analgesic drug classes in several fish species.