Lawsonia intracellularis ELISA: A New Test at the ISU-VDL

Porcine Proliferative Enteropathy (PPE) is a common disease of swine which is caused by the intracellular bacterium, Lawsonia intracellularis. The performance of a recently available commercial ELISA for L. intracellularis was evaluated by comparison with an immuno-peroxidase monolayer assay (IPMA) and found to have at least 97% correlation. The same assay when conducted at different laboratories showed 100% agreement in results. Examination of serum samples from various cases submitted to the Iowa State University Veterinary Diagnostic laboratory indicated that 87% of the herds examined were sero-positive for L. intracellularis. Therefore, the Enzyme-Linked Immunosorbent Assay (ELISA) for Lawsonia intracellularis is a useful and reliable test which allows veterinary practitioners and producers to obtain same day results on swine serum samples submitted

Serological Cross-Reactivity of the Novel H1N1 and Implications for Protection with a Commerical Vaccine

The recent emergence of the pandemic H1N1 viruses and their being labeled as ‘swine flu’ has had several detrimental effects on the pork industry. Novel H1N1 strains have been recently detected in swine populations in the United States and in other parts of the world. While the public health significance of these findings is unknown, it is important to determine whether existing vaccines or exposure to previously circulating strains of swine influenza will protect pigs against the novel H1N1. Using a partial two-way cross-hemagglutination inhibition (HI) assay, we have determined a swine H1N1 strain present in a commercial vaccine cross-reacted with antiserum specific to the novel H1N1. We have also shown that a field serum sample with a HI high titer to a ’99 H1N1 strain crossreacted strongly with the novel H1N1. Anti-sera which were specific to the non-pandemic H1N1 strains also crossreacted with the novel H1N1. Therefore, we conclude that current vaccines and circulating non-pandemic H1N1 field strains will provide at least partial protection against the novel H1N1 virus in pigs

Evaluation and use of a serological assay for the detection of antibodies to Lawsonia intracellularis in swine

Porcine proliferative enteropathy (PPE) is a common and economically important gastro-intestinal disease of swine caused by the intracellular bacterium, Lawsonia intracellularis. Conventional tests to detect antibody responses to L. intracellularisinclude the immuno-peroxidase monolayer assay (IPMA), immuno-fluorescent antibody test (IFAT) and a lipopolysaccharide ELISA (LPS-ELISA). These tests are not commercially available. Therefore, objective of this study is to evaluate the performance of a commercial L. intracellularis blocking ELISA. Performance of the commercial ELISA was compared to the IPMA and LPS-ELISA using serum from experimentally infected animals (N = 40). The prevalence of L. intracellularis sero-positive animals was assessed by comparing suspect and randomly selected sera (N = 394). The commercial ELISA, IPMA and a non-commercial lipopolysaccharide (LPS) LPS-ELISA showed a 95% correlation when tested using experimentally derived known status samples. When compared to the IPMA the sensitivity of the commercial ELISA was 91% while the specificity was 100%. Therefore, the diagnostic sensitivity and specificity of the commercial L. intracellularis ELISA was comparable to the LPS-ELISA and IPMA. A comparison of suspect and randomly selected field samples with the commercial ELISA indicated that L. intracellularis sero-positivity is widespread and does not correlate with possible disease status

Infectivity of porcine circovirus type 2 DNA in semen from experimentally-infected boars

Porcine circovirus type 2 (PCV2) is an economically important pathogen. It has been demonstrated that PCV2 DNA can be detected in boar semen by PCR; however, the biological relevance of this is unknown. The objectives of this study were to determine if semen positive for PCV2 DNA is infectious (1) in a swine bioassay, or (2) when used for artificial insemination. For the first objective, 4-week-old pigs were inoculated intraperitoneally with PCV2 DNA-negative (bioassay-control; n = 3), PCV2a DNA-positive (bioassay-PCV2a; n = 3), or PCV2b DNA-positive (bioassay-PCV2b; n = 3) raw semen, or PCV2 live virus (bioassay-positive; n = 3), respectively. Pigs inoculated with PCV2 DNA-positive semen and PCV2 live virus became viremic and developed anti-PCV2 antibodies indicating that the PCV2 DNA present in semen was infectious. For the second objective, three Landrace gilts were inseminated with PCV2 DNA-negative semen (gilts-controls) from experimentally-infected boars, and six gilts were artificially inseminated with semen positive for PCV2a DNA (gilts-PCV2a; n = 3) or PCV2b DNA (gilts-PCV2b; n = 3). Serum samples collected from the gilts in all groups remained negative for anti-PCV2 antibodies for the duration of the experiment. In addition, fetal serum samples from all 105-day-gestation fetuses were negative for anti-PCV2 antibodies or PCV2 DNA. Under the conditions of this study, PCV2 DNA-positive semen was not infectious when used to artificially inseminate gilts; however, it was demonstrated to be infectious in a swine bioassay model and therefore is a potential means of PCV2 transmission amongst swine herds

Molecular targets for rapid identification of Brucella spp

BACKGROUND: Brucella is an intracellular pathogen capable of infecting animals and humans. There are six recognized species of Brucella that differ in their host preference. The genomes of the three Brucella species have been recently sequenced. Comparison of the three revealed over 98% sequence similarity at the protein level and enabled computational identification of common and differentiating genes. We validated these computational predictions and examined the expression patterns of the putative unique and differentiating genes, using genomic and reverse transcription PCR. We then screened a set of differentiating genes against classical Brucella biovars and showed the applicability of these regions in the design of diagnostic tests. RESULTS: We have identified and tested set of molecular targets that are associated in unique patterns with each of the sequenced Brucella spp. A comprehensive comparison was made among the published genome sequences of B. abortus, B. melitensis and B. suis. The comparison confirmed published differences between the three Brucella genomes, and identified subsets of features that were predicted to be of interest in a functional comparison of B. melitensis and B. suis to B. abortus. Differentiating sequence regions from B. abortus, B. melitensis and B. suis were used to develop PCR primers to test for the existence and in vitro transcription of these genes in these species. Only B. suis is found to have a significant number of unique genes, but combinations of genes and regions that exist in only two out of three genomes and are therefore useful for diagnostics were identified and confirmed. CONCLUSION: Although not all of the differentiating genes identified were transcribed under steady state conditions, a group of genes sufficient to discriminate unambiguously between B. suis, B. melitensis, and B. abortus was identified. We present an overview of these genomic differences and the use of these features to discriminate among a number of Brucella biovars

Swift A New constrained optimization technique

In this paper a new technique for constrained optimization called SWIFT (Sequential weightage increasing factor technique)is rature. This method uses the improved flexible polyhedron method of Ref. 1 as the basic algorithm for unconstrained optimization SWIFT singificantly differs from the existing constrained optimization techniques including SUMT, in the way it penalizes the objective function this in effect has brought about extreme simplipication elegance and fast convergence ti the problem of constrained optimization

SWIFT - A new constrained optimization technique (Sequential Weight Increasing Factor Technique for nonlinear programming)

A new technique for constrained optimization called SWIFT (Sequential Weight Increasing Factor Technique) is presented and compared with some test problems available in the literature. This procedure uses an improved flexible polyhedron method as the basic algorithm for unconstrained optimization. SWIFT significantly differs from existing constrained optimization techniques in the way it penalizes the objective function. This has brought about extreme simplification, elegance and fast convergence to the problem of constrained optimization

Modification of the flexible polyhydron method for function minimisation

In this paper, the Flexible Polyhedron Method for function minimization is improved by incorporating a new idea. This nethod, henceforth to be called the Improved Flexible Polyhedron Method (IFPM), accelerates the search for the minimum. by way of of reducing the number of function evaluations to attain a required accuracy

Lawsonia intracellularis ELISA: A New Test at the ISU-VDL

Porcine Proliferative Enteropathy (PPE) is a common disease of swine which is caused by the intracellular bacterium, Lawsonia intracellularis. The performance of a recently available commercial ELISA for L. intracellularis was evaluated by comparison with an immuno-peroxidase monolayer assay (IPMA) and found to have at least 97% correlation. The same assay when conducted at different laboratories showed 100% agreement in results. Examination of serum samples from various cases submitted to the Iowa State University Veterinary Diagnostic laboratory indicated that 87% of the herds examined were sero-positive for L. intracellularis. Therefore, the Enzyme-Linked Immunosorbent Assay (ELISA) for Lawsonia intracellularis is a useful and reliable test which allows veterinary practitioners and producers to obtain same day results on swine serum samples submitted.</p