Effects of dietary supplementation of meat-type quail breeders with guanidinoacetic acid on their reproductive parameters and progeny performance.

This study was conducted to assess the effect of dietary supplementation of meat-type quail breeders with guanidinoacetic acid (GAA) on their reproductive parameters and progeny performance. Two hundred forty meat-type quails at 25 wk of age were distributed in a completely randomized design with 5 treatments and 8 replicates of 6 birds each. The treatments consisted of 5 dietary levels of GAA (0.00, 0.06, 0.12, 0.18, and 0.24%). The progenies from quail breeders were housed according to breeder treatments and fed a conventional diet based on corn and soybean meal without GAA supplementation. Dietary GAA levels did not affect (P > 0.05) the productivity of meat-type quail breeders, although the concentration of guanidinic compounds (creatine, GAA, and creatinine) in the eggs from the breeders increased linearly (P < 0.05) according to the increase in dietary GAA levels. The number of spermatozoa present in the vitelline membrane was not affected (P > 0.05) by the treatments, but there was a quadratic effect (P < 0.05) of the levels of GAA on fertility, embryonic mortality, and egg hatchability, with the best results estimated at 0.13, 0.15, and 0.14% GAA, respectively. The creatine levels of the pectoral muscle in newborn quails showed a quadratic effect (P ≤ 0.07), and the dietary GAA level of 0.11% was estimated to maximize the muscular creatine level in the progeny. There was a quadratic effect (P < 0.05) of GAA levels on weight gain and feed conversion of progeny at 35 d of age with an optimization point of 0.14% GAA for these variables. Dietary GAA supplementation of meat-type quail breeders increases the availability of creatine in eggs and muscle of progeny, which results in better reproductive parameters and better postnatal progeny performance.

Chondroitin sulphate distribution in broiler chicken carcasses.

1. The content of chondroitin sulphate (CS), known as a nutraceutical, was estimated in broiler chicken carcasses by analysing sulphated glycosaminoglycan uronic acid in posterior sternum (keel) cartilage and bones from 4 parts (wing, leg, front and hind) of carcasses. 2. The results of the present study suggested that approximately 0.63 g CS uronic acid (or 1.9 g as CS) can be extracted from a 1.66 kg whole broiler chicken carcass. The amount of extractable CS from keel cartilage, which has been reported as a valuable source of CS in broiler chicken carcasses, was surprisingly low (<10% of total CS).

Genotype and fetal size affect maternal-fetal amino acid status and fetal endocrinology in Large White × Landrace and Meishan pigs.

This study compared maternal plasma amino acid concentrations, placental protein secretion in vitro and fetal body composition and plasma amino acid and hormone concentrations in feto-placental units from the smallest and a normally-sized fetus carried by Large White × Landrace or Meishan gilts on Day 100 of pregnancy. Compared with Large White × Landrace, Meishan placental tissue secreted more protein and Meishan fetuses contained relatively more fat and protein, but less moisture. Fetal plasma concentrations of insulin, triiodothryonine, thyroxine and insulin-like growth factor (IGF)-II were higher in Meishan than Large White × Landrace fetuses. In both breeds, fetal cortisol concentrations were inversely related to fetal size, whereas concentrations of IGF-I were higher in average-sized fetuses. Concentrations of 10 amino acids were higher in Large White × Landrace than Meishan gilts, while glutamine concentrations were higher in Meishan gilts. Concentrations of alanine, aspartic acid, glutamic acid and threonine were higher in Meishan than Large White × Landrace fetuses. Average-sized fetuses had higher concentrations of asparagine, leucine, lysine, phenylalanine, threonine, tyrosine and valine than the smallest fetus. This study revealed novel genotype and fetal size differences in porcine maternal-fetal amino acid status and fetal hormone and metabolite concentrations.

Antigenic components, isolation and partial characterization of excretion-secretion fraction of Paramphistomum cervi.

The immunogenic components of adult Paramphistomum cervi excretion-secretion (ES) fraction were revealed by SDS-PAGE and immunoblotting technique using sera from cattle naturally infected with P. cervi, Fasciola gigantica, strongylids, Trichuris sp., and Strongyloides sp. By SDS-PAGE, it was found that the ES fraction comprised 13 distinct protein bands. Immunoblotting analysis of these proteins exhibited nine prominent antigenic bands which were recognized by paramphistomosis antisera. These antigenic proteins had molecular weights ranging from 10-170 kDa. One antigenic protein band of 40 kDa was found to give a consistent reaction with sera from all infected cattle. Its diagnostic sensitivity, specificity and accuracy using this test were 100%, 98.9% and 99.3%, respectively. The positive and negative predictive values were 98% and 100%, respectively. The 40 kDa antigen was partially purified by gel filtration and ion-exchange chromatography. The antigenicity of 40 kDa protein for diagnosis of P. cervi infection was confirmed by immunoblotting and indirect ELISA (at 1:78,125 dilution) using a pool of sera and individual serum samples from infected cattle. The present findings suggest that the 40 kDa protein may be used as a diagnostic antigen for paramphistomosis.

Comparative amino acid digestibility for broiler chickens and White Pekin ducks.

A total of 608 three-week-old male broiler chickens and White Pekin ducks were used in a 5-d trial to compare ileal amino acid (AA) digestibility of soybean meal (SBM) and canola meal (CM) using the regression method. A corn-casein-cornstarch-based diet was mixed to contain 15% CP. Cornstarch was replaced with test ingredient (SBM or CM) to contain 18 or 21% of CP in 4 other diets. A nitrogen-free diet (NFD) was used for standardization of apparent digestibility. Birds received a standard starter diet (23% CP) from d 0 to 14 posthatch and then 6 experimental diets for 5 d. On d 19 posthatch, birds were asphyxiated with CO(2), and digesta from the distal section of ileum was collected. The ileal digestibility of AA from the test ingredients was assessed by multiple linear regression analysis using data on daily apparent ileal digestible AA and total AA intakes. The basal endogenous losses of N and all AA for ducks were significantly higher than those for broilers. For ileal AA digestibility by regression of apparent digestible AA intake against AA intake, there was a higher (P < 0.05) digestibility for Cys and Pro in ducks compared with broilers (P < 0.05). Within species, digestibility was not different between SBM and CM except for Lys of ducks, and Lys and Pro of broilers (P < 0.05). The results of this study showed that ducks have higher basal endogenous AA losses compared with broiler chickens as well as higher ileal Cys and Pro digestibility estimates derived from regression approach, indicating that data obtained from broilers should not be used to formulate diets for ducks.

Quantifying phytate in dairy digesta and feces: alkaline extraction and high-performance ion chromatography.

Development of an analytical method with appropriate combination of extraction and quantification approaches for undigested phytate in ruminant feces and digesta will advance knowledge of phytate degradation in ruminants and help to reduce phosphorus excretion. Established quantification methods give satisfactory results for feedstuffs and nonruminant manure but recovery of phytate is incomplete for ruminant feces and digesta because of their complex sample matrix and low ratio of phytate to inorganic P. The objective was to develop a robust, accurate, sensitive, and inexpensive method to extract and quantify phytate in feeds, ruminant feces, and digesta. Diets varying in phytate content were fed to dairy heifers, dry cows, and lactating cows to generate digesta and fecal samples of varying composition to challenge extraction and quantification methods. Samples were extracted with 0.5 M HCl or 0.25 M NaOH + 0.05 M EDTA. Acid extracts were mixed with 20% NaCl, alkaline extracts were acidified to final pH < 2, and then both extracts were clarified with C18 cartridges and 0.2-µm filters. High-performance ion chromatography (HPIC) was used to quantify phytate. In feed samples, the measured phytate was comparable in alkaline and acid extracts (2,965 vs. 3,085 µg/g of DM). In digesta and fecal samples, alkaline extraction yielded greater estimates of phytate content than did acid extraction (40.7 vs. 33.6 and 202.9 vs. 144.4 µg/g of DM for digesta and fecal samples, respectively). Analysis of alkaline extracts by HPIC is usually not possible because of sample matrix interferences; acidification and C(18)-cartridge elution of alkaline extracts prevented this interference. Pure phytate added to dry samples before extraction was almost completely recovered (88 to 105%), indicating high extraction efficiency, no adverse effect of extract clean-up procedures, and accurate quantification of phytate. The proposed method is rapid, inexpensive, robust, and combines the extraction power of NaOH-EDTA with the precision and sensitivity of HPIC quantification, allowing accurate quantification of phytate in feeds, ruminant digesta, and fecal samples.

Erratum: Purification of a toxic cysteine protease produced by pathogenic Aeromonas hydrophila isolated from rainbow trout.

An extracellular lethal toxin produced by Aeromonas hydrophila strain RT860715K originally isolated from diseased rainbow trout (Oncorhynchus mykiss) was purified by using Fast Protein Liquid Chromatography system with hydrophobic interaction chromatography and anion exchange columns. The toxin was a cysteine protease, inhibited by L-cysteine, iodoacetic acid, N-ethylamleimide, P-chloromercuibenzene-sulfonic acid and N-α-p-tosyl-1-lysine-chloromethyl ketone (TLCK), and showed maximal activity at pH 6.0. The molecular weight of the purified enzyme proved to be 94 kDa as estimated by SDS-PAGE. In addition, the toxin was also completely inhibited by HgCl2 but partially inhibited by ethylenediamine tetraacetic acid (EDTA) and CuCl2. Both the extracellular products of Aeromonas hydrophila RT860715K and the purified protease were lethal to rainbow trout (weighing 18 g) with LD50 values of 2.87 and 0.93 µg protein g-1 fish body weight, respectively. The addition of L-cysteine completely inhibited the lethal toxicity of the purified protease, indicating that this cysteine protease was a lethal toxin produced by the bacterium.

Proteomic profile of uterine luminal fluid from early pregnant ewes.

Embryonic development is a time-sensitive period that requires a synchronized uterine environment, which is created by the secretion of proteins from both the embryo and uterus. Numerous studies have identified uterine luminal proteins and related these to specific adaptations during early pregnancy (EP). However, no study has yet utilized LC-MS/MS to identify the signature profile of proteins in the uterine lumen during EP. In this study, uterine luminal fluid from nonpregnant (NP; n = 3) and EP (n = 3; gestational day 16) ewes were analyzed by LC-MS/MS and validated by Western immunoblotting. We identified a unique signature profile for EP luminal fluid; 15 proteins related to specific aspects of embryonic development including growth and remodeling, immune system regulation, oxidative stress balance, and nutrition were significantly altered (up to 65-fold of NP) in EP profile. Specific uterine remodeling proteins such as transgelin (P = 0.008) and placental proteins like PP9 (P = 0.02) were present in EP luminal fluid but were barely detectable in the NP flushings. Direct correlations (R(2) = 0.84, P = 0.01) were observed between proteomics and immunoblotting. These data provide information on dynamic physiological processes associated with EP at the level of the uterus and conceptus and may potentially demonstrate a signature profile associated with embryonic well-being.

Effects of matrix filtration of low-quality boar semen doses on sperm quality.

The aim of this work was to develop a method to enhance the sperm parameters of ejaculates with low sperm quality from Piétrain boars. Seminal doses were filtered through columns of DEAE Sephadex (length 2.5 +/- 0.5 cm), CM Sephadex (length 5 +/- 0.5 cm), glass wool (length 2 +/- 0.5 cm) or glass bead (length 10 +/- 0.5 cm), with an exit flow rate of 1 ml/40 s in all cases. For each male, 10 ml of the sperm cell-rich fraction diluted at 1 : 6 were filtered. Sperm quality was assessed before and after filtration. Sperm morphology, sperm motility and sperm concentration were determined using the computer program sca((R)) 2002 Production, and sperm viability was evaluated by fluorescence multistaining. Osmotic resistance test and hyperosmotic resistance test were used to determine the osmotic resistance of spermatozoa, whereas l-lactate production estimated the metabolic activity. Results showed a decrease of sperm concentration and osmotic resistance of spermatozoa after filtration in the four matrixes. However, an increase in the frequency of viable spermatozoa with intact acrosome after filtration in glass bead columns and an increase of morphologically normal spermatozoa after filtration in Sephadex CM-50, glass wool and glass bead columns were observed. Despite the decrease in the frequency of progressive motile spermatozoa, l-lactate production and mitochondrial sheath integrity maintained constant after filtration. Our findings indicate that column filtration is an effective method to enhance the sperm quality by selecting viable and morphologically normal spermatozoa without altering DNA, plasma membrane, mitochondrial sheath integrity or inducing premature acrosome reaction.

Progesterone and the distribution of pituitary gonadotropin isoforms in cattle.

The objective of the present study was to determine the relative proportion of gonadotropin isoforms in bovine pituitary glands affected by progesterone. Twelve postpubertal heifers (Swiss-Zebu) were assigned to three groups (n=4): intact animals in the luteal phase of the estrous cycle (diestrus group); ovariectomized heifers with (OVXP) or without progesterone treatment (OVX). Prior to pituitary gland collection, a blood sample was taken from each animal to determine the circulating progesterone concentration. Pituitary protein extractions processed by chromatofocusing were eluted with a pH gradient ranging from 10.5 to 3.5. The LH and FSH eluent was grouped on the basis of the following three criteria: (1) as either a basic (pH>or=7.5), neutral (pH 7.4-6.5) and acid (pHor=10.5-3.5); (3) on the basis of distinct isoforms 12 peaks of which (A-L) were identified for LH and 11 (I-XI) for FSH. The analysis by range of pH and by pH of elution in the OVX and OVXP groups showed no difference in the LH and FSH isoform ratio, but diestrus cattle differs having a greater ratio (p<0.05) of basic LH isoforms (87.5+/-0.4%) and lesser ratio (p<0.05) of acid isoforms (5.4+/-0.7%). In the diestrus group, the ratio of acid FSH isoform increased (62.1+/-1.7%), while neutral isoforms decreased (5.7+/-0.4%, P<0.05). The analysis by isoform type of LH revealed a greater proportion of isoforms C (pH 9.4) and E (pH 9.0) in the groups with circulating progesterone when compared to the OVX group. The heterogeneity of FSH was quantitatively similar in most isoforms in the three groups, with the exception of the predominant isoform (VIII, pH 4.9) that was more abundant in the diestrus group (p<0.05). These results indicate that progesterone with other gonad factors influence the pituitary glicosylation altering the relative proportions of gonadotropin isoforms.

Development of a monoclonal antibody-based co-agglutination test to detect enterotoxigenic Escherichia coli isolated from diarrheic neonatal calves.

Escherichia coli (E. coli) strains were collected from young diarrheic calves in farms and field. Strains that expressed the K99 (F5) antigen were identified by agglutination tests using reference antibodies to K99 antigen and electron microscopy. The K99 antigen from a selected field strain (SAR-14) was heat-extracted and fractionated on a Sepharose CL-4B column. Further purification was carried out by sodium deoxycholate treatment and/or ion-exchange chromatography. Monoclonal antibodies to purified K99 antigen were produced by the hybridoma technique, and a specific clone, NEK99-5.6.12, was selected for propagation in tissue culture. The antibodies, thus obtained, were affinity-purified, characterized and coated onto Giemsastained Cowan-I strain of Staphylococcus aureus (S. aureus). The antibody-coated S. aureus were used in a coagglutination test to detect K99+ E. coli isolated from feces of diarrheic calves. The specificity of the test was validated against reference monoclonal antibodies used in co-agglutination tests, as well as in ELISA. Specificity of the monoclonal antibodies was also tested against various Gram negative bacteria. The developed antibodies specifically detected purified K99 antigen in immunoblots, as well as K99+ E. coli in ELISA and co-agglutination tests. The co-agglutination test was specific and convenient for large-scale screening of K99+ E. coli isolates.

Characterization of bovine neutrophil gelatinase-associated lipocalin.

A protein of relative molecular mass of approximately 25,000 was purified from bovine colostrum by cation-exchange and size-exclusion chromatography. The N-terminus of the protein matched the sequence predicted by the National Center for Biotechnology Information for the bovine homolog of human neutrophil gelatinase-associated lipocalin, a glycoprotein of relative molecular mass 25,000 belonging to the family of lipocalins. The protein was further designated as bovine neutrophil gelatinase-associated lipocalin (bNGAL). Sodium dodecyl sulfate-PAGE of enzymically deglycosylated bNGAL indicated that the intact protein bears one N-linked glycan. Monosaccharide and mass spectrometric analyses of released N-linked carbohydrates revealed the presences of complex- and hybrid-type glycans, with galactose substituted with N-acetylgalactosamine. This substitution is typical for glycoproteins expressed in the bovine mammary gland. A specific ELISA revealed bNGAL concentrations in plasma and mature milk of about 0.05 and 1 microg/mL, respectively, whereas values as high as 51 microg/mL were measured in colostrum. Thus, we have isolated and characterized a novel bovine (milk) protein that is a new member of the lipocalin family.

Production and purification of ovine anti-tetanus antibody.

We used the ovine as bioreactor for the production and optimization of anti-tetanus toxin antibody. Four female sheep were immunized with human tetanus vaccine (TT-alum) every two weeks for 16 weeks, after which serum was collected and its titer was estimated by ELISA. The highest titer obtained was 39,000 IU ml-1. To optimize a purification protocol for ovine anti-tetanus toxin, we used four procedures; weak anion (DEAE-Sephadex), weak cation (CM-Sephadex), ammonium sulfate precipitation alone or in combination with caprylic acid. Fifty percent saturation with ammonium sulfate combined with caprylic acid gave us the highest yield of protein with specific activity and the purest Fab product.

Partial characterization and isolation of 130 kDa antigenic protein of Dicrocoelium dendriticum adults.

The study focused on characterizing and isolating Dicrocoelium dendriticum antigens or their fractions that could be used for the immunological diagnosis of dicrocoeliosis. Somatic (SoAg) and excretory-secretory antigens (ESAg) were analyzed by SDS-PAGE and their specificity was evaluated by Western blot with homologous and heterologous sera. The antigens were partially purified by chromatographic techniques of gel-filtration (Sephacryl S-300) and ion exchange (Hitrap-DEAE-Sepharose). Western blot analysis using sera of ovine infected with D. dendriticum revealed eight main antigenic polypeptides ranging from 24 to 205 kDa for SoAg and seven for ESAg with apparent molecular mass in the range of 26-205 kDa. We detected a specific parasite protein with an approximate molecular weight of 130 kDa in SDS-PAGE gels, arranged as a 450 kDa tetramer in native conditions. It also showed strong immunoreactivity by Western blot against ovine sera experimentally infected with D. dendriticum. Gel filtration chromatography (Sephacryl S-300) also showed other specific proteins, one of about 24 kDa in SoAg and another of about 42 kDa in ESAg. The elution conditions of 450 kDa protein (130 kDa monomer) by DEAE chromatography were similar to those from the somatic antigen (pH 7.2, 0.1M NaCl, in 29-34 ml fractions) and from the excretion-secretion antigen (pH 8.0, 0.1M NaCl, in 29-35 ml fractions). The suitability of 130 kDa polypeptide for D. dendriticum infection diagnosis was confirmed by Western blot using a pool of sera as well as individual serum samples from experimentally infected sheep. The sequence of amino termini of 130 kDa polypeptide from both fractions was the same and identical to that reported for a peptide from D. dendriticum described as a globin. This sequence also revealed an appreciable similarity with the amino end of globins from some phylogenetically related worms.

Pattern of circulating luteinizing hormone isoforms during the estrous and luteal phases in Holstein heifers.

The pattern of distribution of circulating luteinizing hormone (LH) isoforms in cattle during estrus and the luteal phase was investigated. In each stage, the stage of the estrous cycle was synchronized in seven Holstein heifers with a prostaglandin analogue. After estrus was detected, blood samples were taken at 2-h intervals for 24h. In the luteal phase, animals received 250 microg i.v. of GnRH and blood samples were collected every 15 min for 5h. LH concentration in the samples was determined. Samples with the greatest LH concentration in estrus (pre-ovulatory peak) and those collected 60 min after GnRH administration (luteal phase) were analyzed by chromatofocusing, eluted with a pH gradient from 10.5 to 3.5. Eluted LH was grouped into basic (pH > or = 7.5), neutral (pH 7.4-6.5) and acidic isoforms (pH < or = 6.4) as well as by pH unit. In both phases, basic forms were the most abundant, and these were greater (P < 0.05) during the luteal phase (78.4 +/- 4.2%) as compared with during estrus (57.1 +/- 6.2%); the proportion of neutral and acidic isoforms in estrus (13.7 +/- 2.6%; 28.5 +/- 2.8%) was greater (P < 0.05) as compared with the luteal phase (3.0 +/- 0.7; 18.7 +/- 3.4). These results indicate that the relative proportion of LH isoforms secreted by the adenohypophysis differ by stage of estrous cycle. The addition of excess of NaCl to the column modifies the antigen-antibody binding in the RIA, and the proteins eluted are erroneously quantified as LH; this is an artifact of the technique.

Effects of dietary supplementation with sodium chloride on urinary relative supersaturation with calcium oxalate in healthy dogs.

OBJECTIVE: To evaluate the effect of dietary supplementation with sodium chloride (NaCl) on urinary calcium excretion, urine calcium concentration, and urinary relative supersaturation (RSS) with calcium oxalate (CaOx). ANIMALS: 6 adult female healthy Beagles. PROCEDURE: By use of a crossover study design, a canned diet designed to decrease CaOx urolith recurrence with and without supplemental NaCl (i.e., 1.2% and 0.24% sodium on a dry-matter basis, respectively) was fed to dogs for 6 weeks. Every 14 days, 24-hour urine samples were collected. Concentrations of lithogenic substances and urine pH were used to calculate values of urinary RSS with CaOx. RESULTS: When dogs consumed a diet supplemented with NaCl, 24-hour urine volume and 24-hour urine calcium excretion increased. Dietary supplementation with NaCl was not associated with a change in urine calcium concentration. However, urine oxalate acid concentrations and values of urinary RSS with CaOx were significantly lower after feeding the NaCI-supplemented diet for 28 days. CONCLUSIONS AND CLINICAL RELEVANCE: Dietary supplementation with NaCl in a urolith-prevention diet decreased the propensity for CaOx crystallization in the urine of healthy adult Beagles. However, until long-term studies evaluating the efficacy and safety of dietary supplementation with NaCl in dogs with CaOx urolithiasis are preformed, we suggest that dietary supplementation with NaCl be used cautiously.

An immunoturbidimetric assay for rapid quantitative measurement of feline alpha-1-acid glycoprotein in serum and peritoneal fluid.

BACKGROUND: Alpha-1-acid glycoprotein (AGP) is an acute phase protein that increases in concentration in infectious and inflammatory conditions. The serum and peritoneal fluid concentrations of AGP may be useful in the diagnosis of feline infectious peritonitis (FIP), a lethal disease of cats. Currently AGP can be measured by radioimmunodiffusion (RID) assays, which are time consuming and difficult. OBJECTIVES: The objectives of this study were to develop a rapid immunoturbidimetric assay for measurement of AGP in feline serum and peritoneal fluid and to compare the results with those obtained by RID. METHODS: AGP was purified by perchloric acid precipitation and ion-exchange chromatography from a pool of peritoneal fluid obtained from cats with FIP, as determined by a panel of laboratory tests, including serum AGP concentration, albumin: globulin ratio, and total protein concentration, anti-coronavirus antibody titers, and effusion analysis. The purified AGP in a complete Freund's adjuvant and Tween 20 mixture was injected into a sheep and blood was collected at monthly intervals. Anti-AGP antiserum, as confirmed by ELISA and Western blot techniques, and a pool of peritoneal fluid from cats with FIP were used to prepare standards. Clinical samples of feline peritoneal fluid (n=55) and serum (n=59) were assayed for AGP and results from the immunoturbidimetric and RID methods were compared. RESULTS: Significant correlation (P < .001) was obtained between methods for both peritoneal fluid (R2=.9259) and serum (R2=.9448) samples. Coefficients of variation for the immunoturbidimetric method were <5%. CONCLUSIONS: This rapid immunoturbidimetric assay for measurement of feline AGP in serum and peritoneal fluid may be of value in the diagnosis of FIP and possibly other inflammatory diseases in cats.

Immunogenicity of major cell surface protein(s) of Brucella melitensis Rev 1.

Brucella melitensis Rev 1 organisms were salt-extracted and the cell surface proteins (BCSPs) were found to be mainly 39-42 kDa (group 2 porin proteins) in addition to 31.6, 32.5, 58.5 and 14.7 kDa proteins. DEAE-Sephadex anion-exchange column chromatography of BCSPs yielded fraction 1, which contained one major protein (39.8-42.0 kDa) and a minor protein (31.6 kDa). All these proteins were found to be immunogenic by Western blotting. Fraction 1 along with monophosphoryl lipid A and trehalose dicorynomycolate adjuvants as well as BCSPs alone induced significant (p < or = 0.05) protection in BALB/c mice. Both these immunizing agents produced almost equivalent protection to live B. melitensis Rev 1 vaccine at 15 and 30 days post challenge. Lymphocyte stimulation test as well as delayed-type hypersensitivity reaction revealed that both these preparations induced cell-mediated immune response. These preparations also induced humoral immune response as indicated by indirect ELISA. Neither of the immune responses was significantly less (p < or = 0.05) than that with live B. melitensis Rev 1 vaccine, except that their duration was short.

Enhanced sensitivity of an antibody competitive blocking enzyme-linked immunosorbent assay using Equine arteritis virus purified by anion-exchange membrane chromatography.

In an effort to improve a competitive blocking enzyme-linked immunosorbent assay (cELISA) for antibody detection to Equine arteritis virus (EAV), antigen purified by anion-exchange membrane chromatography capsule (AEC) was evaluated. Virus purification by the AEC method was rapid and easily scalable. A comparison was made between virus purified by the AEC method with that obtained by differential centrifugation based on the following: 1) the relative purity and quality of EAV glycoprotein 5 (GP5) containing the epitope defined by monoclonal antibody 17B7, and 2) the relative sensitivity of a commercial antibody cELISA with the only change being the 2 purified antigens. On evaluation by Western blot using GP5-specific monoclonal antibody 17B7, the AEC-purified EAV contained 86% GP5 monomer whereas the differentially centrifuged EAV contained <29% of the monomer. Improvement of analytical sensitivity without sacrifice of analytical specificity was clearly evident when cELISAs prepared with EAV antigen by each purification method were evaluated using 7 sensitivity and specificity check sets. Furthermore, the AEC-purified EAV-based cELISA had 30-40% higher agreement with the virus neutralization (VN) test than the cELISA prepared with differentially centrifuged EAV based on testing 40 borderline EAV-seropositive samples as defined by the VN test. In addition, the AEC-purified cELISA had highly significant (P = 0.001) robustness indicated by intra-laboratory repeatability and interlaboratory reproducibility when evaluated with the sensitivity check sets. Thus, use of AEC-purified EAV in the cELISA should lead to closer harmonization of the cELISA with the World Organization for Animal Health-prescribed VN test.

Functional expression of the catalytic domains of two cysteine proteinases from Trypanosoma congolense.

The catalytic domains of two closely related cysteine proteinases (CP1 and CP2) from Trypanosoma congolense, referred to as C1 and C2, were expressed as proforms in Escherichia coli (C1) and in the baculovirus system (C1 and C2). While the bacterial expression system did not allow recovery of active C1, the baculovirus system led to secretion of inactive zymogens which could be processed at acidic pH into mature enzymes. Active C1 and C2 were purified from serum-free culture supernatants by anion-exchange chromatography and characterised. Their kinetic parameters and pH activity profiles confirmed the relatedness between C2 and native CP2 (congopain). These properties also underline major functional differences between C1 and C2, that appear to relate to discrete but essential sequence differences. It is likely that these two enzymes perform distinct roles in vivo, in the parasite and/or in the host-parasite relationships.