Biomedical subjects

A Lundén

Publications and source records attributed to A Lundén.

At least 19 recordsLinked to original sources

PubMed2005

Mononuclear cell subsets in bronchoalveolar lavage fluid during Dictyocaulus viviparus infection of calves: a potential role for gamma/delta TCR-expressing cells in airway immune responses?

Mononuclear cell populations in the lungs of calves infected with Dictyocaulus viviparus were studied during primary infection and reinfection in order to identify cells involved in development of protective immunity to parasitic bronchitis. Three groups of calves were either inoculated with 500 third-stage larvae at both weeks 0 and 10 (n = 6), inoculated only at week 10 (n = 6), or remained uninfected (n = 3). The animals were monitored weekly by collection of bronchoalveolar lavage fluid (BALF), blood and faeces. Among mononuclear BALF-cell populations, the gamma/delta TCR-expressing cells showed a pronounced transient increase in proportion as well as in relative cell size 2 weeks post primary infection, whereas CD4-, CD8-, Ig- and CD14-expressing cells showed no significant differences related to the infection. The increase in gamma/delta TCR-expressing cells coincided with significantly increased proportions of eosinophils and recovery of adult worms in BALF. After reinfection, gamma/delta TCR-expressing cells increased again, but not until week 3 post inoculation, whereas eosinophils were increased by week 2 and reached higher levels than after primary infection. After reinfection, establishment of D. viviparus was less successful than after primary infection. In conclusion, these results indicate a role for gamma/delta TCR-expressing lymphocytes in the pathogenesis of D. viviparus infection.

Animals↗

PubMed2001

In vivo and in vitro lipidation of recombinant immunogens for direct iscom incorporation.

We have previously reported strategies for Escherichia coli production of recombinant immunogens fused to hydrophobic tags to improve their capacity to be incorporated into an adjuvant formulation (J. Immunol. Methods 222 (1999) 171; 238 (2000) 181). Here, we have explored the possibility to use in vivo or in vitro lipidation of recombinant immunogens as means to achieve iscom incorporation through hydrophobic interaction. For the in vivo lipidation strategy, a general expression vector was constructed encoding a composite tag consisting of a sequence (lpp) of the major lipoprotein of E. coli, fused to a dual affinity fusion tag to allow efficient recovery by affinity chromatography. Upon expression in E. coli, fatty acids would be linked to the produced gene products. To achieve in vitro lipidation, the target immunogen would be expressed in frame with an N-terminal His6-ABP affinity tag, in which the hexahistidyl tag was utilized to obtain lipidation via a Cu2+-chelating lipid. A 238 amino acid segment DeltaSAG1, from the central region of the major surface antigen SAG1 of Toxoplasma gondii, served as model immunogen in this study. The two generated fusion proteins, lpp-His6-ABP-DeltaSAG1 and His6-ABP-DeltaSAG1, both expressed at high levels (approximately 5 and 100 mg/l, respectively), could be recovered to high purity by ABP-mediated affinity chromatography, and were evaluated in iscom-incorporation experiments. The His6-ABP-DeltaSAG1 fusion protein was associated to iscom matrix with pre-incorporated chelating lipid. Both fusion proteins were found in the iscom fractions after analytical ultracentrifugation in a sucrose gradient, indicating successful iscom incorporation/association. Iscom formation was further supported by electron microscopy analysis. In addition, these iscom preparations were demonstrated to induce high-titer antigen-specific antibody responses upon immunization of mice. For this particular target immunogen, DeltaSAG1, the induced antibodies demonstrated poor reactivity to the native antigen, although slightly better for the preparation employing the in vitro lipidation strategy, indicating that DeltaSAG1 was suboptimally folded or presented. Nevertheless, we believe that the presented strategies offer convenient alternative ways to achieve efficient adjuvant incorporation for recombinant immunogens.

Amino Acid Sequence↗

PubMed2001

A previous infection with Toxoplasma gondii does not protect against a challenge with Neospora caninum in pregnant sheep.

Sheep immunized with Toxoplasma gondii (Toxovax) prior to pregnancy were tested for their ability to withstand a challenge at 90 days gestation with 107 Neospora caninum (NC1) tachyzoites. The antibody responses in sheep following immunization with T. gondii were specific for T. gondii whereas peripheral blood mononuclear cells responded to both T. gondii and N. caninum antigen in vitro. This suggested that there was induction of crossreactive immune recognition in the sheep, at least at the cellular level. Following challenge of sheep at mid-gestation with N. caninum, no febrile responses were recorded in the group of sheep which had previously received Toxovax while significant febrile responses were recorded in the group of sheep which received N. caninum challenge alone. Antibody responses to N. caninum developed in all sheep following N. caninum challenge and antibody responses to T. gondii were boosted in the group of sheep which had previously been immunized with Toxovax. No antibodies to T. gondii were observed in the sheep which received the N. caninum challenge alone. Peripheral blood mononuclear cells from both groups of sheep responded to T. gondii and N. caninum antigen in vitro and interferon gamma was present in the cell-free supernatant from activated cells. However despite evidence of the induction of crossreactive immunity between T. gondii and N. caninum, this was not sufficient to prevent foetal death. The group of sheep which had received Toxovax prior to pregnancy and the group of sheep which only received the N. caninum challenge experienced 100% foetal death compared with 0% in the unchallenged control group. Vaccination prior to pregnancy with Toxovax did protect against foetal death following oral challenge at 90 days with 2000 T. gondii oocysts which caused 100% foetal death in a control challenge group.

Animals↗

PubMed2001

Immunity to experimental neosporosis in pregnant sheep.

Neospora caninum is an important cause of fetal loss in cattle but has also infrequently been shown to cause disease in sheep and goats. Experimental infection of pregnant sheep with N. caninum causes clinical and pathological changes very similar to those of neosporosis in cattle. An experiment in sheep was undertaken to examine whether infection with N. caninum before pregnancy conferred immunity to subsequent challenge with the parasite during pregnancy. Primary inoculation of NC1 tachyzoites subcutaneously, either before or during pregnancy, caused a significant temperature response in ewes, while those given a secondary challenge at 90 days gestation (dg) did not show such a response. Primary infection of 12 ewes during pregnancy resulted in the loss of all fetuses while a further 12 ewes inoculated with NC1 tachyzoites before mating and subsequently challenged with the same dose at 90 dg produced nine live and seven dead lambs. There were no fetal deaths in ewes only infected with Neospora before mating although there was serological evidence of vertical transmission in four of their clinically normal offspring while Neospora DNA was detected in the cerebrospinal fluid of a fifth healthy lamb. Thus an experimental primary infection with N. caninum during pregnancy killed all the fetuses while inoculation before pregnancy did not cause any mortality but did provide a degree of protection against subsequent challenge with Neospora during pregnancy.

Animals↗

PubMed2001

Sporulation of Eimeria maxima oocysts in litter with different moisture contents.

The aim of this study was to determine if the sporulation of Eimeria maxima oocysts was affected by the moisture content of the litter. Fresh feces were collected from chickens experimentally infected with E. maxima. The feces were mixed with dried wood shavings and different amounts of water to obtain final moisture contents of 16, 42, and 62% and a final oocyst concentration of 5,000 per g of mixture. The samples were kept at 23 C and 75% relative humidity and were thoroughly aerated every 12 h. Oocysts kept under ordinary laboratory sporulation conditions in 2% wt/vol aqueous potassium dichromate at 27 C were used as a standard for optimal sporulation. The proportion of sporulated oocysts was determined microscopically every 12 h. Sporulation of E. maxima was most efficient under the driest conditions studied (16% moisture content), and poorest in the samples with the highest moisture content (62%). Even though the differences may not have resulted from a direct effect of humidity on the oocysts, but more likely resulted from limited oxygen in the moister substrates, it is clear that sporulation is not favored by moist litter.

Animals↗

PubMed2000

Intestinal digesta viscosity decreases during coccidial infection in broilers.

1. The effect of intestinal digesta viscosity on bird performance in chickens with coccidiosis was compared to those without coccidiosis. 2. Six hundred chicks were divided into five groups: one control group was fed a basal maize/soyabean-based diet and the other groups were fed the basal diet supplemented with 2, 4, 6 or 8 g carboxymethyl cellulose (CMC) per kg of feed. At 14 d of age half the birds were individually inoculated with sporulated oocysts of Eimeria acervulina and Eimeria praecox. 3. Intestinal digesta viscosity increased with increasing inclusion of CMC. This effect was considerably less pronounced in inoculated than in non-inoculated birds. 4. There was a significant negative effect on live weight gain and feed conversion ratio (FCR) with increasing CMC inclusion in non-inoculated birds, but in inoculated birds there was no clear relation between CMC inclusion and performance. Neither intestinal lesion scores, nor numbers of Clostridium pefringens in the caeca, were significantly affected by CMC inclusion. 5. Across all diets inoculation impaired growth rate by 9% and FCR by 8%, but did not affect the amount of C. perfringens in the caeca.

Animals↗

PubMed2000

Eimeria infections in litter-based, high stocking density systems for loose-housed laying hens in Sweden.

1. Coccidiosis, caused by different Eimeria species, is believed to be a more prominent problem in loose-housed layers kept on litter than in battery cages. In this study, the impact and development of Eimeria infections were investigated in layers kept in litter-based, high stocking density systems for loose-housed hens. 2. Layers from 57 flocks on 26 farms were followed by necropsy of a representative sample of birds that died or had to be culled. Coccidiosis was diagnosed in 11 flocks (19.3%) from 9 (31%) of the farms. The outbreaks occurred when the birds were 19 to 32 weeks old. E. maxima was identified in 6 and E. tenella in 3 of the outbreaks. 3. Sixteen of the flocks were also monitored with faecal and litter samples collected at regular intervals. Oocysts were detected in samples from all these flocks. The pattern of oocyst excretion was similar in most of the flocks, with maximum counts at 4 to 8 weeks after introduction to the laying house. There was no significant correlation between the levels of oocysts in faeces and clinical coccidiosis. 4. Raising pullets without any coccidiostat, to increase their chance to develop immunity against coccidia, was not found to decrease the risk of coccidiosis during the production period when compared to the practice of giving amprolium and ethopabate during the rearing period.

Amprolium↗

PubMed1999

Comparison between a live, attenuated anticoccidial vaccine and an anticoccidial ionophore, on performance of broilers raised with or without a growth promoter, in an initially Eimeria-free environment.

An experiment was carried out to study the effects of vaccination with Paracox, a live, attenuated vaccine against avian coccidiosis, on broilers isolated from extraneous Eimeria parasites. The study involved 3200 broiler chickens raised in floor pens similar to commercial conditions, but in an initially Eimeria-free environment. Forty percent of the chickens were vaccinated at 3 days of age and given either a basal unmedicated feed or a feed supplemented with the feed antibiotic virginiamycin. Unvaccinated birds were given either the basal feed or feed supplemented either with virginiamycin or the anticoccidial ionophore narasin. At slaughter at 36 days of age vaccinated birds had a lower live weight than non-vaccinated birds. The difference was 4.6% in unmedicated, and 6.0% in virginiamycin medicated chickens. Feed conversion ratio at slaughter was 2.5% higher for unmedicated vaccinated birds, and 1.3% higher for virginiamycin medicated vaccinated birds, compared to respective non-vaccinated groups. There was no significant difference in overall performance of unvaccinated birds given narasin as compared to virginiamycin. At 10 days post vaccination vaccinated birds had a higher number of Clostridium perfringens in the caeca, but there was no difference thereafter. Throughout the experiment, caecal clostridial counts were considerably higher in vaccinated unmedicated birds than in unvaccinated birds given narasin. The number of oocysts shed in the vaccinated groups was very low, but during a subsequent challenge with E. maxima and E. tenella the birds' immunity was found to be satisfactory.

Animals↗

PubMed1999

Serum antibodies to bovine coronavirus in Swedish sheep.

Altogether 218 sheep sera from 40 flocks in different parts of Sweden were screened for antibodies to bovine coronavirus (BCV). Nineteen per cent of the sera were positive and there was a significantly higher frequency (p < 0.05) of at least one positive sample in flocks with more than 100 adult sheep than in smaller flocks. There was also a significantly higher frequency (p < 0.001) of positive samples from sheep older than 4 years than from younger ones. Only a weak relationship between BCV positivity (2 or more positive samples, p < 0.05) and cattle contact was demonstrated in this study. Possible transmission routes and other factors that could have affected the result are discussed. In light of our finding that all 5 sheep experimentally exposed to BCV through contact with infectious cow faeces seroconverted, we conclude that the antibodies found in Swedish sheep are probably the result of BCV infections directly or indirectly transmitted from cattle.

Age Factors↗

PubMed1998

Polychlorinated naphthalenes and other organochlorine contaminants in Swedish human milk, 1972-1992.

The concentrations of polychlorinated naphthalenes (PCNs) were determined together with polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), 1,1-bis-(4-chlorophenyl)-2,2,2-trichloroethane (p,p'-DDT), 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) and hexachlorobenzene (HCB) in milk, sampled in the course of 1972-92 from mothers living in Stockholm. A previously developed method for multicomponent analysis of organochlorine environmental contaminants was adapted for simultaneous analysis of PCNs. The mean recoveries of seven chlorinated naphthalene (CN) congeners added to milk prior to extraction were 76-99%. Similar recoveries were obtained for the commercial PCN product Halowax 1014. The pattern of PCNs in milk differed to a great extent from that in the commercial PCN products. The dominating congeners in breast milk were 1,2,3,5,7-pentachloronaphthalene (CN-52), 1,2,3,4,6,7- and/or 1,2,3,5,6,7-hexachloronaphthalene (CN-66/ CN-67) and one unidentified tetrachloronaphthalene. There was a notable decrease in the concentrations of PCNs as was of the other organochlorine contaminants in milk from 1972 to 1992. During this time period the sum of CN congeners decreased from 3,081 to 483 pg/g milk fat and the sum of toxic equivalents of dioxin and dioxin-like compounds decreased from 100 to 39 pg/g milk fat.

Benzofurans↗

PubMed1998

Application of iscom antigen preparations in ELISAs for diagnosis of Neospora and Toxoplasma infections.

Immunostimulating complexes (iscoms) are cage-like structures of about 40 nm composed of Quil A, cholesterol, phospholipids and antigen. Their main area of use has been as adjuvants and carriers of immunogens in vaccines. Iscoms can also be used for selection of surface membrane proteins of micro-organisms for use in immunoassays, thus decreasing the number of internal proteins that might cause problems with non-specific binding and cross-reactivity. Enzyme-linked immunoassays (ELISAs) utilising parasite antigens incorporated into iscoms have been developed for demonstration of antibodies directed to the intracellular coccidian parasites Toxoplasma gondii and Neospora caninum. These iscom ELISAs have proved very reliable, with high sensitivity and specificity. The preparation of T. gondii and N. caninum iscoms is described, and ELISAs based on iscom antigen preparations that have so far been used for diagnosis of protozoal infections are reviewed.

Animals↗

PubMed1998

Identification of Neospora antigens recognized by CD4+ T cells and immune sera from experimentally infected cattle.

Neospora caninum is recognized as a major cause of infectious abortion in cattle. Very little is known about immunity to Neospora. Cell mediated responses have previously been shown to be important in the development of protective immunity to the closely related parasite Toxoplasma gondii, and may therefore be an important component in the immune response to Neospora. In this paper we report that a group of low molecular weight NCI strain tachyzoite antigens (< or = 30 kDa) separated by SDS PAGE and bound to nitrocellulose membrane stimulated proliferation in vitro of CD4+ T cells from calves experimentally infected with N. caninum. Proliferation was accompanied by production of high concentrations of IFN-gamma. Several of these antigens were also recognized by antibody produced in these animals. As the most effective vaccines require the stimulation of both humoral and cell mediated immune responses, these antigens may be important in the development of a vaccine against neosporosis.

Animals↗

PubMed1998

Cellular immune responses in cattle experimentally infected with Neospora caninum.

Neospora caninum has recently been identified as an important cause of infectious abortion in cattle. The parasite is closely related to Toxoplasma gondii, but the two species are antigenically distinct. To examine cell proliferative responses and the induction of IFN-gamma in experimentally infected cattle, four 2-4 months old calves were subcutaneously inoculated with N. caninum tachyzoites. Peripheral blood mononuclear cells were collected regularly and stimulated in vitro with a crude lysate of N. caninum or T. gondii tachyzoites. Significant proliferative responses to N. caninum antigen were recorded in all calves from days 4-6 postinoculation. This response was accompanied by production of high levels of IFN-gamma. Although the calves remained seronegative to T. gondii, while seroconverting to N. caninum, stimulation with T. gondii lysate resulted in cell proliferation of a similar magnitude as that obtained using the N. caninum lysate. However, the T. gondii lysate appeared less effective than the N. caninum lysate to stimulate IFN-gamma production. Cells taken from uninfected control animals did not show any significant proliferation to either N. caninum or T. gondii antigen and no IFN-gamma was produced. These results suggest that the two parasites may possess cross-reacting T-cell epitopes, but that the T cells specific for N. caninum may have a different functional capacity. This highlights the need to investigate the antigen specificity and cytokine profile of T cells from infected animals to help understand their role in immunity to N. caninum.

Animals↗

PubMed1998

Mapping of serum amylase-1 and quantitative trait loci for milk production traits to cattle chromosome 4.

The present study was undertaken to confirm and refine the mapping of a quantitative trait locus in cattle for milk fat percentage that had earlier been reported to be linked to the serum amylase-1 locus, AM1. Five half-sib families from the previous study and 7 new ones were genotyped for nine microsatellite markers spanning chromosome 4. AM1 was mapped between the microsatellite markers BMS648 and BR6303. In a granddaughter design, interval mapping based on multiple-marker regression was utilized for an analysis of five milk production traits: milk yield, fat percentage and yield, and protein percentage and yield. In the families reported on previously, significant effects for fat and protein percentages were detected. In the new families, an effect on milk and fat yields was found. The most likely positions of the quantitative trait locus in both groups of families were in the same area of chromosome 4 in the vicinity of the obese locus. Direct effects of the obese locus were tested for using polymorphism in two closely linked microsatellites located 2.5 and 3.6 top downstream of the coding sequence. No firm evidence was found for an association between the obese locus and the tested traits.

Amylases↗

PubMed1997

Use of a recombinant antigen, SAG2, expressed as a glutathione-S-transferase fusion protein to immunize mice against Toxoplasma gondii.

The capacity of Toxoplasma gondii surface protein SAG2 to induce protective immunity against the parasite in mice was studied using recombinant SAG2 expressed as a glutathione-S-transferase (GST) fusion protein incorporated into immune stimulating complexes (iscoms). Immunization with the iscoms resulted in the production of antibodies recognizing SAG2 as well as GST. After oral challenge infection with T. gondii oocysts or tissue cysts, no protective effect was observed. On the contrary, mice immunized with fusion SAG2 or with GST iscoms died earlier than non-immunized control mice.

Animals↗

PubMed1997

Marked effect of beta-lactoglobulin polymorphism on the ratio of casein to total protein in milk.

The relationship between genetic variants for milk protein and the composition of milk was analyzed on 4475 repeated milk samples from individual cows; 371 dairy cows of the Swedish Red and White breed and 204 cows of the Swedish Holstein breed were used. The registrations included percentages of casein, protein, fat, and lactose in combination with milk yield and SCC. The genotype of individual cows for alpha(s1)-CN, beta-CN, kappa-CN, and beta-LG was determined by alkaline and acidic PAGE. A mixed animal model was used for the analysis; beta-LG and aggregate casein genotypes were included simultaneously as separate fixed effects in the statistical model. The results suggest a positive additive effect of the beta-LG B allele on casein content and on the ratio of casein to total protein. For the latter trait, the beta-LG genotype accounted for a relatively large part of the phenotypic variance, corresponding to a reduction in residual variance of 11% when included in the model. The corresponding value for casein content was 0.5%. The lack of unfavorable associations between milk protein variants and the traits included in this study makes the beta-LG gene an obvious candidate when the breeding objective is improved conversion of milk protein into cheese.

Animals↗

PubMed1996

Iscoms in parasitological research.

During the history of vaccine development, a number of adjuvants and adjuvant formulations have been tested and evaluated for their ability to increase the immunogenicity of different antigens. In this review, Anna Lundén, Karin Lövgren Bengtsson, Anders Sjölander and Arvid Uggla focus on iscoms (immune stimulating complexes), their characteristics and applications to different types of parasitic antigens.

Journal Article↗

PubMed1996

Methylsulfonyl metabolites of PCBs and DDE in human milk in Sweden, 1972-1992.

A multicomponent method used for analysis of organochlorine pesticides, polychlorinated biphenyls (PCBs), naphthalenes, dibenzo-p-dioxins, and dibenzofurans was adapted for the analysis of methylsulfonyl metabolites of chlorinated biphenyls (MeSO2-CBs) and of p,p'-DDE (MeSO2-DDE) in human milk. The extraction and initial purification was made by liquid-gel partitioning. Additional purification and separation steps were achieved by adsorption and gel permeation chromatography. The mean recoveries of 23 MeSO2-CBs and MeSO2-DDE standards, added to the milk before extraction, were 80-97%. Human milk sampled in Stockholm during 1972, 1976, 1980, 1984/85, 1990, 1991, and 1992 was analyzed by GC-MS. During the time course studied, the concentrations of MeSO2-CBs decreased from approximately 9 to 2 ng/g lipids and of MeSO2-DDE from 5 to 0.4 ng/g lipids. The concentrations of MeSO2-CBs and MeSO2-DDE correlated to the levels of total PCB and p,p'-DDE, respectively. 3-MeSO2-DDE was the major isomer of the aryl methyl sulfones studied in the milk. PCB methyl sulfones with five and six chlorine atoms in the molecule were predominant among the PCB methyl sulfones Generally, the concentrations of 4-MeSO2-CBs were higher than the corresponding 3-MeSO2-CB compound. The major MeSO2-CBs in the milk were 4-MeSO2-2,5,2',3',4'-pentaCB (4-87) and 4-MeSO2-2,3,6,2',4',5'-hexaCB (4-149).

Female↗