Molecular characterization of reticuloendotheliosis virus insertions in the genome of field and vaccine strains of fowl poxvirus

Evidence of the widespread occurrence of reticuloendotheliosis virus (REV) sequence insertions in fowl poxvirus (FPV) genome of field isolates and vaccine strains has increased in recent years. However, only those strains carrying a near intact REV provirus are more likely to cause problems in the field. Detection of the intact provirus or REV protein expression from FPV stocks has proven to be technically difficult. The objective of the present study was to evaluate current and newly developed REV and FPV polymerase chain reaction (PCR) assays to detect the presence of REV provirus in FPV samples. The second objective was to characterize REV insertions among recent "variant" FPV field isolates and vaccine strains. With REV, FPV, and heterologous REV-FPV primers, five FPV field isolates and four commercial vaccines were analyzed by PCR and nucleotide sequence analysis. Intact and truncated REV 5' long terminal repeat (LTR) sequences were detected in all FPV field isolates and vaccine strains, indicating heterogeneous REV genome populations. However only truncated 3' LTR and envelope sequences were detected among field isolates and in one vaccine strain. Amplifications of the REV envelope and 3' LTR provided strong evidence to indicate that these isolates carry a near intact REV genome. Three of the four FPV vaccine strains analyzed carried a solo complete or truncated 5' LTR sequence, indicating that intact REV provirus was not present. Comparison of PCR assays indicated that assays amplifying REV envelope and REV 3' LTR sequences provided a more accurate assessment of REV provirus than PCR assays that amplify the REV 5' LTR region. Therefore, to differentiate FPV strains that carry intact REV provirus from those that carry solo 5' LTR sequences, positive PCR results with primers that amplify the 5' LTR should be confirmed with more specific PCR assays, such as the envelope, or the REV 3' LTR PCR.     

An epidemic of salmonellosis caused by Salmonella Typhimurium DT160 in wild birds and humans in New Zealand

AIM: This study reports an outbreak of salmonellosis due to S. Typhimurium DT160 which caused extensive mortality in wild birds and enteric disease in humans in New Zealand during the winter and spring months of the year 2000. METHODS: Necropsies were performed and microbiological examinations undertaken on wild birds from populations in which mass mortality was reported, and on captive indigenous birds which died suddenly during the winter and spring of 2000. Affected tissues were examined histologically and isolates of S. Typhimurium were phage typed and examined using pulsedfield gel electrophoresis (PFGE). Isolates of S. Typhimurium obtained from cases of human enteric disease which occurred during these months were phage typed, examined using PFGE and compared with the bird isolates. RESULTS: Central and northern areas of the South Island and the southern North Island were worst affected with die-offs of several hundreds of sparrows and other birds reported in rural areas. Mortalities reached a peak in winter (July-August) 2000 and decreased to small numbers during the spring and early summer. The birds usually died of an acute septicaemia with multifocal necrotising lesions in the liver and spleen. Human cases throughout the country increased gradually over the same period. Isolates from birds, livestock and humans examined using PFGE were indistinguishable from one another. CONCLUSION: This strain of Salmonellahas emerged as a major cause of septicaemia in wild birds in New Zealand. Because of the close association between house sparrows (Passer domesticus) and humans, the organism also poses a serious zoonotic risk. The possibility that the infection may spread to involve indigenous species needs investigation.     

Effect of dam and sire qualitative hip conformation scores on progeny hip conformation

OBJECTIVE: To determine in dogs what effect using hip conformation scores assigned by the Orthopedic Foundation for Animals (OFA) as a criterion for breeding selections would have on hip conformation scores of the progeny. DESIGN: Longitudinal study. ANIMALS: English Setters, Portuguese Water Dogs, Chinese Shar-peis, and Bernese Mountain Dogs for which OFA hip conformation scores were known. PROCEDURE: Pedigree data were obtained from the national breed clubs and the American Kennel Club and merged with data from the OFA hip conformation score database. An ANOVA was used to evaluate the effects of sex, age at the time of radiographic evaluation, and year of birth on the variation in hip conformation scores among the progeny. Heritability was estimated by use of within-year midparent offspring regression analyses. RESULTS: Significant differences in progeny hip conformation scores between sexes were not detected, but age at the time of radiographic evaluation and year of birth had a significant effect on hip joint conformation of the progeny. Estimated heritability (mean +/- SE) was 0.26 +/- 0.03, and dam and sire hip conformation scores had a significant effect on progeny hip conformation scores. Annual decreases in percentage of dysplastic progeny and increases in percentages of progeny and breeding dogs with phenotypically normal hip joint conformation were detected. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that hip conformation scores have moderate heritability in dogs and selection of breeding stock with better hip conformation scores will increase the percentage of progeny with phenotypically normal hip joint conformation.     

Diagnosis of eastern equine encephalitis by immunohistochemistry in two flocks of Michigan ring-neck pheasants

The diagnosis of eastern equine encephalitis (EEE) virus infection in avian species is relatively difficult when compared with other species. There are no characteristic histologic lesions in the avian brain that would serve to distinguish EEE from infections with, for example, Newcastle disease or highly pathogenic avian influenza virus. Traditionally, virus isolation (VI) and/or hemagglutination inhibition (HI) has been used for a definitive diagnosis of EEE in birds. Recently, we developed an immunohistochemistry (IHC) technique for confirmatory diagnosis of EEE infection in equine brain. This test also detected EEE virus in formalin-fixed avian brain. VI confirmed IHC finding in two cases of EEE in ring-neck pheasants. IHC is a rapid, sensitive test for confirming and differentiating a histopathologic diagnosis of EEE in avian species and should be considered as an alternative test to VI or HI.     

Immune status of PIC Camborough-15 sows, 25% Meishan sows, and their offspring kept indoors and outdoors

Newer genetic lines of pigs are being used in indoor and outdoor production systems. The objectives of Exp. 1 were to describe the effects of the maternal sow line genotype, environment (indoor vs outdoor), and the genotype x environment interactions on blood hemoglobin (Hb), immunoglobulin G (IgG) concentrations, white blood cell (WBC) numbers, lymphocyte transformation/blastogenesis (LTA), natural killer (NK) cell activity, neutrophil chemotaxis, cortisol concentrations, and leukocyte differentials. Studies were performed using two genotypes: PIC Experimental-94 (Exp-94, an experimental line containing 25% Meishan) and PIC Camborough-15 (C-15). The Exp-94 sows had lower LTA at 0.2 microg/mL mitogen than the C-15 sows, whereas Exp-94 sows had higher NK cytotoxicity than the C-15 sows. When indoors, the two genotypes showed similar neutrophil chemotaxis. When outdoors, the C-15 genotype had higher (P < .01) neutrophil chemotaxis than the Exp-94 sows. The other immune measures were statistically similar for the two genotypes for each environment and for the genotype x environment interaction of sows. Experiment 2 sought to determine the effects of genotype on the immune system of nursery-age offspring of the experimental lines. Each sow line was bred to a common PIC 405 boar line. The Exp-94 x 405 pigs had elevated WBC numbers than C-15 x 405 pigs. The social status of the Exp-94 x 405 or the C-15 x 405 pigs showed no effect on any of the immune measures studied. The other immune measures were statistically similar for the two lines of pigs. The Exp-94 line had marginally increased NK activity but reduced lymphocyte blastogenesis and neutrophil chemotaxis compared with the C-15 line.     

Intracerebroventricular Infusion of Leptin into Mature Merino Rams of Different Metabolic Status: Effects on Blood Concentrations of Glucose and Reproductive and Metabolic Hormones

In mature Merino rams, nutrition is one of the external cues that most strongly affects the reproductive centres of the preoptic-hypothalamic continuum. The signalling pathways that link dietary status and the activity of the neurones that produce gonadotrophin-releasing hormone signals are thought to be partly hormonal in nature to reflect the amount of body reserves. Among the hormones thought to be involved are insulin and leptin. This study tested whether recombinant bovine leptin infused (0.4 microg/h) into the third cerebral ventricle would stimulate pulsatile luteinizing hormone (LH) secretion in mature Merino rams when their energy status was low or decreasing, during both chronic (fasting) and acute reductions of energy balance. Leptin may interact with other hormones that depend on energy availability, so we also monitored changes in circulating concentrations of insulin, thyroid hormones, growth hormone, prolactin and adrenocorticotrophin. Overall, our data do not support this hypothesis. The dietary regimes induced clear responses in the metabolic profiles of the animals but there was no clear effect of central leptin administration on LH pulse frequency. The relationships between the hormonal systems measured in the present study add weight to the contention that leptin plays only a permissive role in the nutritional control of the reproductive axis and that other hormonal signals (particularly insulin) or pathways are acting in concert with leptin to stimulate the reproductive axis.     

Semitendinosus tenotomy for treatment of fibrotic myopathy in the horse

The medical records and follow-up data for 4 horses with fibrotic myopathy of the semitendinosus muscle treated by semitendinosus tenotomy were reviewed. The gait deficit for each of the 4 horses was typical of fibrotic myopathy. Two of the horses had the gait deficit since birth. The efficacy of semitendinosus tenotomy was compared with the traditional treatment of partial myotenectomy of the affected muscle. The functional results in the 4 horses appeared to be equal to partial myotenectomy in returning the horses to athletic function and, compared with what has been reported, was cosmetically superior.     

Identification of bovine herpesvirus-1 polypeptides involved in serum neutralization

Bovine herpesvirus (infectious bovine rhinotracheitis virus)-infected cell antigens were solubilized with Nonidet P-40. The crude antigen extract was separated by reaction with bovine hyperimmune serum in line immunoelectrophoresis; individual immunoprecipitates were used to immunize rabbits. Rabbit sera possessing serum neutralizing activity were analyzed by reaction with crude antigen extract in immunoprecipitation sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot. Four virus-specified glycopeptides, with molecular weights of 69-75K, 77-81K, 82-92K and 108-115K, appeared to be involved in inducing serum neutralizing antibody.     

Antibodies to Aujeszky's disease virus in pigs immunized with purified virus glycoproteins

Antibodies to Aujeszky's disease virus (ADV) glycoproteins gII, gIII, and gp50 were compared using four in vitro tests. Antibodies generated by vaccination with a modified-live vaccine (MLV) were also compared. The serological assays employed were: serum neutralization test (SNT), complement facilitated serum neutralization test (C'SNT), complement-mediated cytolysis and antibody dependent cellular cytotoxicity (ADCC). Pigs were immunized with single glycoproteins twice 14 days apart, or once with the modified-live vaccine. Fourteen days after the second immunization, sera were collected. Virus neutralizing activity (SNT) was demonstrated in the sera from all pigs immunized with gp50 and in one out of three immunized with gIII. Sera from the MLV group all had neutralization titers higher than animals immunized with single glycoproteins. Addition of guinea pig complement to the serum neutralization test (i.e., C'SNT) produced an enhancement of antibody titers in all groups except the pigs immunized with gIII. The complement-mediated cytolysis test rendered antibody titers similar in magnitude for all pigs immunized with single glycoproteins, but slightly lower than values for MLV vaccinated pigs. ADCC activity was clearly displayed in sera from pigs immunized with gIII or vaccinated with MLV, whereas sera from pigs immunized with gII or gp50 had a minimal response. The results indicate that the relative efficiency of antibodies against ADV glycoproteins in protection should be considered for selecting or producing gene-deleted strains for use in vaccine production.