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K Dalsgaard

Publications and source records attributed to K Dalsgaard.

At least 19 recordsLinked to original sources
PubMed1997

Plant-derived vaccine protects target animals against a viral disease.

The successful expression of animal or human virus epitopes on the surface of plant viruses has recently been demonstrated. These chimeric virus particles (CVPs) could represent a cost-effective and safe alternative to conventional animal cell-based vaccines. We report the insertion of oligonucleotides coding for a short linear epitope from the VP2 capsid protein of mink enteritis virus (MEV) into an infectious cDNA clone of cowpea mosaic virus and the successful expression of the epitope on the surface of CVPs when propagated in the black-eyed bean, Vigna unguiculata. The efficacy of the CVPs was established by the demonstration that one subcutaneous injection of 1 mg of the CVPs in mink conferred protection against clinical disease and virtually abolished shedding of virus after challenge with virulent MEV, demonstrating the potential utility of plant CVPs as the basis for vaccine development. The epitope used occurs in three different virus species-MEV, canine parvovirus, and feline panleukopenia virus- and thus the same vaccine could be used in three economically important viral hosts-mink, dogs, and cats, respectively.

Amino Acid Sequence↗
PubMed1995

Full protection in mink against mink enteritis virus with new generation canine parvovirus vaccines based on synthetic peptide or recombinant protein.

Two recently developed vaccine--one based on synthetic peptide and one based on recombinant capsid protein--fully protected dogs against heavy experimental canine parvovirus (CPV) infection. The high sequence homology ( > 98%) and antigenic similarity between CPV and mink enteritis virus (MEV), feline panleukopenia virus, and raccoon parvovirus, suggest that both vaccines could protect mink, cats and raccoons against these respective host range variants. This was tested in mink and turned out to be the case. The two vaccines were fully protective and as effective as a conventional commercial vaccine based on inactivated virus. Surprisingly, this protection was obtained after only a single injection. Furthermore, the vaccinal dose of 150 micrograms of conjugated peptide or 3 micrograms of recombinant VP2 particles per animal, are sufficiently low to be cost-effective and applicable on a large scale.

Amino Acid Sequence↗
PubMed1994

Effective induction of neutralizing antibodies with the amino terminus of VP2 of canine parvovirus as a synthetic peptide.

Fourteen synthetic peptides corresponding to previously mapped antigenic sites in VP2 of canine parvovirus (CPV) were used for immunization of rabbits to identify antiviral properties favourable for inclusion into a vaccine. Most antipeptide antisera obtained were reactive with viral protein, and with one of them it was possible to locate the hypothetical amino terminus of VP3 within positions 15-31 of VP2. Virus-neutralizing antibodies were only obtained with two overlapping 15-mer peptides corresponding in sequence to the amino terminus of VP2 (MSDGAVQPDGGQPAVRNERAT). Antibodies in the neutralizing sera bound most strongly to amino acids of the sequence DGGQPAV within the N-terminus of VP2, indicating that efforts to develop a synthetic vaccine against CVP should be focused on this stretch of amino acids. The two peptides induced long-lasting immunity (at least 8 months) using either Freund's adjuvant or aluminium hydroxide plus Quil A. Thus, this approach delineated the exact peptide sequence useful for vaccines applied to the amino-terminal region of VP2. These findings in experimental animals form a solid basis for exploration of a synthetic peptide vaccine against parvovirus infection in dogs, minks or cats.

Adjuvants, Immunologic↗
PubMed1994

First peptide vaccine providing protection against viral infection in the target animal: studies of canine parvovirus in dogs.

A synthetic peptide vaccine which protects dogs against challenge with virulent canine parvovirus is described. The amino acid sequence used was discovered in previous studies on the immunogenic properties of previously mapped antigenic sites and represents the amino-terminal region of viral protein VP2. As with marker vaccines, it is possible to discriminate between vaccinated dogs that have not been exposed to the virus and dogs that have been infected with the virus. The protective mechanism can be explained by a humoral response against the peptide aided by T-cell epitopes contained in the carrier protein used for peptide coupling. This is the first example of a synthetic peptide vaccine that induces protection in target animals.

Amino Acid Sequence↗
PubMed1993

Topographical analysis of canine parvovirus virions and recombinant VP2 capsids.

The distribution of epitopes defined by monoclonal antibodies (MAbs) on the surface of canine parvovirus (CPV) virions and recombinant VP2-capsids was established using immunoelectron microscopy. A correlation appeared to exist between the linear position, neutralizing activity and immunogold staining. Both viral capsids and recombinant capsids gave similar patterns of immunostaining. The neutralizing MAbs that recognized epitopes not previously identified by Pepscan or immunoblotting gave a clear staining. However, MAbs 3C9 and 3C10, identified by Pepscan and immunoblotting as recognizing linear epitopes, did not show any labelling (3C9) or only scattered labelling (3C10). MAb 3C9 recognizes an N-terminal domain of VP2. MAb 4AG6, which recognizes the same linear epitope as 3C10, did not bind to the capsids, indicating a different orientation. An immunofluorescence assay was performed to supplement the B cell epitope characterization. In contrast to other MAbs that gave nuclear and cytoplasmic staining, MAb 3C9 gave a preferential nuclear staining. Based on these results, it is hypothesized that the N terminus of VP2 is barely, or not at all, exposed on the surface of the native virions, but becomes accessible after some virion steric change (e.g. after attachment to the cell receptor).

Animals↗
PubMed1993

Specific T-cell recognition of the merozoite proteins rhoptry-associated protein 1 and erythrocyte-binding antigen 1 of Plasmodium falciparum.

The merozoite proteins merozoite surface protein 1 (MSP-1) and rhoptry-associated protein 1 (RAP-1) and synthetic peptides containing sequences of MSP-1, RAP-1, and erythrocyte-binding antigen 1, induced in vitro proliferative responses of lymphocytes collected from Ghanaian blood donors living in an area with a high rate of transmission of malaria. Lymphocytes from a large proportion of the Ghanaian blood donors proliferated in response to the RAP-1 peptide, unlike those of Danish control blood donors, indicating that this sequence contains a malaria-specific T-cell epitope broadly recognized by individuals living in an area with a high transmission rate of malaria. Most of the donor plasma samples tested contained immunoglobulin G (IgG) and IgM antibodies recognizing the merozoite proteins, while only a minority showed high IgG reactivity to the synthetic peptides.

Adolescent↗
PubMed1993

B-cell epitopes of canine parvovirus: distribution on the primary structure and exposure on the viral surface.

Ten antigenic sites on canine parvovirus (CPV) were mapped with a complete set of overlapping nonapeptides of the capsid proteins VP1 and VP2: five of these sites were recognized by sera from CPV-infected dogs, three were recognized by a rabbit anti-CPV antiserum, and two were recognized by murine monoclonal anti-CPV antibodies. A region covering the first 21 amino-terminal amino acid residues of VP2 was recognized by three sera from infected dogs, one neutralizing rabbit antiserum, and one neutralizing murine monoclonal antibody. Immunoabsorption experiments with full virions indicated that at least 6 of the 10 antigenic sites are located on the surface. Of these six, three sites occur in the amino terminus of VP2. When superimposed on the three-dimensional structure of canine parvovirus (J. Tsao, M. S. Chapman, M. Agbandje, W. Keller, K. Smith, H. Wu, M. Luo, T. J. Smith, M. G. Rossmann, R. W. Compans, and C. R. Parrish, Science 251:1456-1464, 1991), the other three epitopes are located on two loops of VP2 which form the highly exposed "spike" around the threefold-symmetry axis of the virus. Thus, these regions (amino terminus and loops 1 and 3) are of interest as major target sites for induction of neutralizing antibodies.

Amino Acid Sequence↗
PubMed1992

Iscom immunization with synthetic peptides representing measles virus hemagglutinin.

Synthetic peptides representing the measles virus (MV) hemagglutinin (MVH) were incorporated into immunostimulating complexes (iscoms) and used for immunization of rabbits. Nine regions of MVH were selected on the basis of hydropathy and antigenicity profiles, by use of the known primary structure of MVH. Six linear and three branched types of peptides were synthesized and conjugated to palmitic acid before incorporation into the iscom structure. Five of the anti-peptide sera reacted by ELISA with the homologous peptide but did not react with MV in the native state, indicating that either the selected sites are not represented on the surface of MV, or they could be a conformational epitope. Human-anti MV and rabbit anti-MV did not react with the peptides.

Amino Acid Sequence↗
PubMed1992

Production of porcine parvovirus empty capsids with high immunogenic activity.

The VP2 gene of porcine parvovirus was cloned in the baculovirus system and expressed in insect cells. The resulting product was present in high yield. It self-assembled into particles which were structurally and antigenically indistinguishable from regular PPV capsids. A high degree of purity of the recombinant capsids was obtained by ammonium sulphate precipitation of cell lysates. These virus-like particles were used as antigen in the immunization of two pigs. The pigs elicited an immune response which, when assayed by standard serological techniques, was identical to that of a commercial vaccine. The amount of recombinant antigen needed in a vaccine dose was only 3 micrograms in a primary dose and 1.5 micrograms in the booster.

Animals↗
PubMed1992

A novel subunit ISCOM vaccine against bovine virus diarrhoea virus.

The preparation and preliminary testing of a subunit ISCOM (immunostimulating complex) vaccine against bovine virus diarrhoea virus (BVDV) is described. Vaccination of calves with this vaccine yields high neutralising titres against a panel of Danish BVDV field isolates. The serological difference between virus isolates and vaccine strain selection is discussed.

Animals↗
PubMed1991

Specific sequence amplification of bovine virus diarrhea virus (BVDV) and hog cholera virus and sequencing of BVDV nucleic acid.

The pestiviruses are small enveloped RNA viruses and are causative agents of economically important animal diseases in cattle, swine, sheep and goats worldwide. We used the polymerase chain reaction to amplify one common fragment of several different strains of both hog cholera virus and bovine virus diarrhea virus (BVDV). The fragment is located at the 5'-end of the genome immediately upstream of the open reading frame. This is a highly conserved region among the different published pestivirus sequences. An internal restriction digest of the amplified fragment with XhoI and PstI was performed in order to confirm specificity of the amplified fragment. The fragment was sequenced for a number of different BVDV strains, and the sequences obtained were compared to those published and used to deduce genetic relationships between strains. Apart from this common fragment we have amplified several other fragments of the Danish BVDV strain Ug59 and obtained specific amplification fragments of the expected size.

Animals↗
PubMed1991

Isolation and characterization of a soluble antigen complex of Plasmodium falciparum with pyrogenic properties.

A soluble antigen complex, previously designated antigen no. 7 (Ag7) on the basis of the pattern obtained by crossed immunoelectrophoresis of culture supernatants of P. falciparum, was isolated by affinity chromatography. It was shown to be synthesized at the schizont stage of the parasite growth cycle and to be located on the surface of the schizonts. Antibodies to Ag7 did not inhibit the growth of the parasite in vitro. Ag7 is recognized by immune human sera from many parts of the world and it stimulated the production of specific antibody in mice when incorporated into immune-stimulating complex (ISCOM) structures. It also specifically stimulated in vitro proliferation of lymphocytes from clinically immune adults. That it induced the secretion of interleukin 1 by human monocytes and was pyrogenic in rabbits was of particular interest. Thus Ag7 has endotoxin-like properties which make it a possible candidate for an antitoxic malaria vaccine.

Animals↗
PubMed1989

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. III. Rotavirus infection.

The prevalence of rotavirus infection was studied in 1090 litters from 26 sow herds. Samples of normal, semifluid and watery stools were examined for rotavirus by an ELISA-test on faeces. Rotavirus was detected in 77% of the herds and in 30.5% of the litters (prevalence rates). The highest prevalence rate was seen in piglets between 21 and 41 days of age. Gilts' litters had a very high prevalence during the first week of life. Apart from this, no difference was found between litters from gilts and older sows. Rotavirus was detected more frequently in semiliquid, loose stools than in normal or watery stools, and an association between virus detection and diarrhoea could not be demonstrated. However, litters which shedded rotavirus during the suckling period had lower weight gains and higher incidence rates of respiratory diseases than virus-free litters. Litters weaned at 2 weeks in battery cages had slightly increased risk of shedding rotavirus compared to litters weaned in more traditional systems. The study revealed that rotavirus is widespread in Danish swine herds. The findings give evidence to suggest that the type of mild diarrhoea in 3-week-old piglets known as steatorrhoea or "white scours" may be associated with rotavirus infection, possibly in combination with E. coli and other agents. The high prevalence in piglets weaned at 2 weeks plus the higher morbidity and mortality among such piglets sustain the conclusion that piglets should not be weaned before 3 weeks of age or below a body weight of 6-7 kg.

Age Factors↗
PubMed1987

Adjuvants.

A number of adjuvants of importance in veterinary vaccines are reviewed. These include mineral salt adjuvants, oil adjuvants, hydrophilic and hydrophobic bloc polymers, hydrocarbons and surface active agents. The current and future applications of these substances and their possible modes of action are discussed. Creation of an adjuvant register by the newly formed European Adjuvant Group should facilitate accumulation of information on adjuvants.

Adjuvants, Immunologic↗