MAGNETIC RESONANCE IMAGING OF CEREBRAL CORTICAL NECROSIS (POLIOENCEPHALOMALACIA) IN A DOG

A 3-year-old neutered female mixed breed dog was examined because of severe, generalized seizure activity, tetraparesis, and encephalopathic signs. Cerebrospinal fluid (CSF) evaluation was unremarkable except for a mild increase in protein. Serum and CSF titers for infectious diseases were negative. Magnetic resonance (MR) imaging examination of the brain was performed and lesions were found within the cerebral gray matter of the temporal and parietal lobes. The lesions had increased signal intensity on T1, T2, and proton density-weighted images. There was mild inhomogeneous enhancement following intravenous contrast medium administration. Neurologic status improved and the seizures were well controlled, but the dog never regained normal mentation and euthanasia was performed 10 weeks after initial evaluation. At necropsy, severe cerebral cortical necrosis was found in the regions corresponding to the lesions seen on MR imaging examination. Large numbers of fat-containing macrophages (gitter cells) were found within these areas, and are thought to be responsible for the characteristic hyperintensity seen on the MR images.     

North American veterinary pathology residency training programs: an overview of where they are today and where they were five years ago, with an analysis of trends

An e-mail/telephone survey of all active North American residency training programs in veterinary pathology was conducted in September 2005. The purpose of this survey was to determine current numbers of trainees, their program length and type, and salaries; to compare current numbers to five years earlier; and, finally, to gauge interest in expanding current programs. All 41 training institutions contacted responded to the survey. Briefly, the survey found that there are currently 235 veterinary pathology residents, for a mean of 5.7 residents per training program. The number of residents currently in training programs and the number of applicants for these programs has increased compared to five years earlier. There is widespread interest in further expanding capacity in these programs, and the coalition of the American College of Veterinary Pathologists and the Society of Toxicologic Pathology is a well-known source of possible funding for additional residents. This survey report further documents the numbers of combined residency/PhD programs, average starting salaries for new residents, outside sponsorship effects on pathology training programs, and some of the common concerns regarding veterinary pathology training programs voiced by the respondents. While residency training capacity has expanded in the last five years, and there is widespread desire to further expand these training programs, a shortage of veterinary pathologists for future market needs will need to be addressed by increased funding from as yet unspecified sources.     

Effect of immunosuppressive doses of cyclosporine on pancreatic beta cell function in pigs

OBJECTIVE: To evaluate whether immunosuppressive doses of cyclosporine (CsA) have an adverse effect on the liver, kidney, and pancreatic beta cells of pigs. ANIMALS: 8 juvenile 8-week-old Landrace X Large White crossbred pigs. PROCEDURE: CsA (100 to 140 mg/kg) was administered orally to euglycemic pigs to reach whole blood trough concentrations of approximately 1500 ng/mL. To determine pancreatic beta cell function, plasma C-peptide and insulin concentrations were measured in response to i.v. administration of glucose, glucagon, arginine, and oral administration of glucose. Effects on liver and kidney were determined by monitoring serum measurements of liver function and serum creatinine concentrations, respectively. RESULTS: Plasma concentrations of C-peptide were significantly lower in euglycemic CsA-treated pigs, compared with control pigs, following i.v. administration of glucose, glucagon, arginine, and oral administration of glucose. Furthermore, the glucose clearance rate was decreased in euglycemic CsA-treated pigs, compared with control pigs. Serum creatinine concentrations and 4 of 7 serum measurements of liver function were not adversely affected by CsA administration. Serum concentrations of bilirubin and albumin were significantly increased, and serum alanine aminotransferase activity was significantly decreased in CsA-treated pigs, compared with control pigs. Histologic evaluation of liver and kidney sections revealed no pathologic findings in CsA-treated or control pigs. CONCLUSIONS AND CLINICAL RELEVANCE: In our study, immunosuppressive doses of CsA caused an impairment of porcine pancreatic beta cell function, but did not have toxic effects on the kidney. However, on the basis of changes in serum bilirubin and albumin concentrations and alanine aminotransferase activity, subclinical toxic effects on the liver did occur when immunosuppressive doses of CsA were administered.     

Mechanical transmission of porcine reproductive and respiratory syndrome virus throughout a coordinated sequence of events during cold weather

Using a field-based model, mechanical transmission of porcine reproductive and respiratory syndrome virus (PRRSV) was assessed throughout a coordinated sequence of events that replicated common farm worker behavior during cold weather (< 0°C). The model involved fomites (boots and containers), vehicle sanitation, transport, and the movement of personnel. A field strain of PRRSV was inoculated into carriers consisting of snow and water, and carriers were adhered to the undercarriage of a vehicle. The vehicle was driven approximately 50 km to a commercial truck washing facility where the driver's boots contacted the carriers during washing, introducing the virus to the vehicle interior. The vehicle was then driven 50 km to a simulated farm site, and the driver's boots mechanically spread virus into the farm anteroom. Types of containers frequently employed in swine farms (styrofoam semen cooler, metal toolbox, plastic lunch pail, and cardboard animal health product shipping parcel) contacted drippings from footwear on the anteroom floor. The truck wash floor, vehicle cab floor mats, boot soles, anteroom floor, and the ventral surface of containers were sampled to track the virus throughout the model. Ten replicates were conducted, along with sham-inoculated controls. At multiple sampling points PRRSV nucleic acid was detected in 8 of 10 replicates. In each of the 8 PCR-positive replicates, infectious PRRSV was detected on the surfaces of containers by virus isolation or swine bioassay. All sham-inoculated controls were negative. These results indicate that mechanical transmission of PRRSV can occur during coordinated sequence of events in cold weather.     

DNA Vaccination Partially Protects Muskellunge against Viral Hemorrhagic Septicemia Virus (VHSV-IVb)

Abstract

A DNA vaccine containing the glycoprotein (G) gene of the North American viral hemorrhagic septicemia virus (VHSV) genotype IVb was developed to evaluate the immune response of fish following vaccination and evaluate its efficacy in protecting a susceptible species, the Muskellunge Esox masquinongy, against VHSV-IVb challenge. Seven weeks (539 degree-days) following vaccination with 10 μg of either pVHSivb-G or a control plasmid, Muskellunge were challenged by immersion with 10⁵ plaque-forming units (pfu)/mL of VHSV-IVb. Fish vaccinated with pVHSivb-G had a relative percent survival (RPS) of 45%. Vaccinated fish also had significantly lower mean viral titers in tissues (4.2 × 10² pfu/g) and viral prevalence (4%) than fish receiving the plasmid control vaccine (3.3 × 10⁵ pfu/g; 82%). Neutralizing antibodies were detected 28 d (308 degree-days) postchallenge (11 weeks postvaccination) in 100% of Muskellunge vaccinated with pVHSivb-G compared with only 12% of plasmid-control-vaccinated Muskellunge, suggesting robust induction of a secondary, adaptive immune response. In addition, pVHSivb-G–vaccinated Rainbow Trout Oncorhynchus mykiss challenged 7 d (100 degree-days) postvaccination with the heterologous novirhabdovirus, infectious hematopoietic necrosis virus (IHNV), experienced an RPS of 61%, compared to control fish, suggesting induction of an early and transient nonspecific antiviral immune response. This study provides an important starting point for VHSV-IVb vaccine development and useful information about the antiviral immune response elicited by DNA vaccination in a nondomesticated fish species.

Received May 1, 2016; accepted September 1, 2016     

Chromosome and plasmid-encoded N-acyl homoserine lactones produced by Agrobacterium vitis wildtype and mutants that differ in their interactions with grape and tobacco

Agrobacterium vitis causes crown gall disease on grapevines. It also induces a specific necrosis on grape roots and a hypersensitive response (HR) on tobacco that are regulated by a complex quorum-sensing regulatory system. Strain F2/5 produces at least six N-acyl-homoserine lactones (AHLs) that function as signal molecules in quorum-sensing. The AHLs differ in acyl side chain length (8–16 carbons) as determined by gas chromatography/mass spectrometry and electrospray ionization tandem mass spectrometry. Mutant derivatives of F2/5 differ in ability to cause necrosis and the HR and show variable AHL profiles as determined by a thin-layer chromatography/biosensor assay. All wildtype A. vitis strains revealed the presence of long-chain AHLs regardless of tumorigenicity or ability to cause the HR. Whereas genes encoding long-chain AHLs are predicted to reside on the F2/5 chromosome, the determinants for short-chain AHLs were shown to be located on conjugal plasmids.     

Mineralisation of atrazine, metolachlor and their respective metabolites in vegetated filter strip and cultivated soil

In vegetated filter strips (VFS) the presence of perennial vegetation, rhizodeposition of labile organic substrates and the accumulation of an organic residue thatch layer may enhance microbial numbers and activity, thereby increasing the potential for mineralisation of herbicides and herbicide metabolites retained during run-off events. The objective of this laboratory experiment was to compare the mineralisation of atrazine and metolachlor with that of their respective metabolites in VFS and cultivated soil. With the exception of total bacteria, propagule density of the microbial groups, endogenous soil enzymes and microbial diversity were higher in the VFS soil. This correlated with increased mineralisation of metolachlor and its metabolites in the VFS soil and indicates potential for VFS to curtail the subsequent transport of these compounds. In contrast, the mineralisation of atrazine and the majority of its metabolites was substantially reduced in VFS soil relative to cultivated soil. Consequently, the potential for subsequent transport of atrazine and many of its metabolites may be greater in VFS soil than in cultivated soil if reduced mineralisation is not offset by increased sorption in the VFS.     

The coat proteins and putative movement proteins of isolates of Prunus necrotic ringspot virus from different host species and geographic origins are extensively conserved

A complete sequence for the RNA 3 of Prunus necrotic ringspot virus (PNRSV) is described (Genbank Accession U57046). Primers from this sequence were used to amplify both the movement protein and coat protein genes of 3 other isolates of PNRSV originating from different host species and geographic locations. Comparisons of these sequences with those of other published sequences for PNRSV and the closely related apple mosaic virus (ApMV) showed that both the movement proteins and coat proteins of isolates of PNRSV are extensively conserved irrespective of either the original host or the geographic origin. The movement protein and coat protein of ApMV and PNRSV are sufficiently conserved to suggest that these two viruses may have evolved from a common ancestor. The amino acid sequence of the two coat proteins shows areas of similarity and difference that would explain the serological continuum reported to occur among isolates of these two viruses. Nevertheless, the movement protein and coat protein of the two viruses are sufficiently different so that ApMV and PNRSV should be considered to be distinct viruses.