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C Vela

Publications and source records attributed to C Vela.

At least 37 records · Page 2Linked 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↗
PubMed1997

Serologic markers in early stages of African horse sickness virus infection.

Fifteen horses were experimentally infected with African horse sickness virus (AHSV) serotype 4. To learn more about the time course of production and specificity of AHSV-specific antibodies, sera were analyzed by immunoblot analysis. Only animals that survived for more than 9 days were able to develop a humoral immune response detectable by immunoblotting. The earliest serological markers corresponded mainly to VP5, VP6, and NS2 and to a lesser extent to VP3, NS1, and NS3. Neutralizing antibodies to VP2 were not detected by immunoblotting, suggesting that they are mostly conformation dependent. VP7-specific antibodies were detected later in infection. These results make NS2 and VP6 the most attractive candidates for the rapid diagnosis of the infection.

African Horse Sickness↗
PubMed1996

Oral immunization of rabbits with VP60 particles confers protection against rabbit hemorrhagic disease.

Rabbit hemorrhagic disease virus (RHDV) causes more than 90% mortality in adult rabbits. In this study, the cDNA of the VP60 coding sequence of RHDV was cloned under the control of the polyhedrin and p10 promoters of baculovirus to be expressed in insect cells. The expression of RHDV VP60 under the control of the p10 promoter was 5-10 times higher than using the polyhedrin promoter. The p10-derived VP60 was able to assemble into virus-like particles (VLPs). RHDV VLPs were successfully used to protect rabbits against the disease even at doses as low as 0.5 micrograms when injected intramuscularly or subcutaneously. The ability to elicit an immune response was independent of the adjuvant or the route of immunization. Remarkably, oral administration of RHDV VLPs efficiently induced protecting antibodies to RHD at doses as low as 3 micrograms. The use of binary ethylenimine for the stabilization of the VLPs was decisive for eliciting a good oral immunity. This report demonstrates the potential use of these procapsids in obtaining RHD oral vaccines and opens the door to the use of these capsids for the prevention of the disease in wild animals. Therefore, a new, and potentially important application of recombinant VLPs in the induction of protective immunity by the oral route is foreseen.

Administration, Oral↗
PubMed1996

Full protection against African horsesickness (AHS) in horses induced by baculovirus-derived AHS virus serotype 4 VP2, VP5 and VP7.

African horsesickness virus serotype 4 (AHSV-4) outer capsid protein VP2, or VP2 and VP5 plus inner capsid protein VP7, derived from single or dual recombinant baculovirus expression vectors were used in different combinations to immunize horses. When the proteins were purified by affinity chromatography, the combination of all three proteins induced low levels of neutralizing antibodies and conferred protection against virulent virus challenge. However, purified VP2 or VP2 and VP5 in the absence of VP7 failed to induce neutralizing antibodies and protection. Immunization with non-purified proteins enhanced the titres of neutralizing antibodies. Again, the combination of the three proteins was able to confer total protection to immunized horses, which showed absence of viraemia. The antigenicity of recombinant VP2 was analysed with a collection of 30 MAbs. Both purified and unpurified recombinant VP2 proteins showed different antigenic patterns in comparison to that of VP2 on virions. An immunization experiment with four more horses confirmed these results. The vaccine described here would not only prevent the disease, but would drastically reduce the propagation of the virus by vectors.

African Horse Sickness↗
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↗
PubMed1995

Peptide vaccine against canine parvovirus: identification of two neutralization subsites in the N terminus of VP2 and optimization of the amino acid sequence.

The N-terminal domain of the major capsid protein VP2 of canine parvovirus was shown to be an excellent target for development of a synthetic peptide vaccine, but detailed information about number of epitopes, optimal length, sequence choice, and site of coupling to the carrier protein was lacking. Therefore, several overlapping peptides based on this N terminus were synthesized to establish conditions for optimal and reproducible induction of neutralizing antibodies in rabbits. The specificity and neutralizing ability of the antibody response for these peptides were determined. Within the N-terminal 23 residues of VP2, two subsites able to induce neutralizing antibodies and which overlapped by only two glycine residues at positions 10 and 11 could be discriminated. The shortest sequence sufficient for neutralization induction was nine residues. Peptides longer than 13 residues consistently induced neutralization, provided that their N termini were located between positions 1 and 11 of VP2. The orientation of the peptides at the carrier protein was also of importance, being more effective when coupled through the N terminus than through the C terminus to keyhole limpet hemocyanin. The results suggest that the presence of amino acid residues 2 to 21 (and probably 3 to 17) of VP2 in a single peptide is preferable for a synthetic peptide vaccine.

Amino Acid Sequence↗
PubMed1994

Antilymphocyte globulins versus OKT3 as prophylactic treatment in highly sensitized renal transplant recipients.

Monoclonal antibodies were proposed as an effective prophylactic immunosuppressive treatment in highly sensitized patients (HSP). In this study we compared the results obtained in HSP treated with OKT3 or antilymphocyte globulins (ALG). From January 1989 to January 1993, 38 transplantations were performed in patients with high panel reactive antibodies (PRA > 50%). The group comprised 22 women and 16 men, mean age 45 +/- 2 (23-67) years; ten were second grafts and two were third grafts. Peak PRA was > or = 80% in 24 sensitized patients and 50-80% in 14 sensitized patients. Patients were randomly assigned to either prophylactic OKT3 (n = 15) or ALG (n = 23). Oral cyclosporin A (10 mg/kg) was started at day 8 in the OKT3 group and when the serum creatinine level decreased to 200 micromol/l in the ALG group. OKT3 was systematically withdrawn on day 10 but ALG was stopped only when total blood cyclosporin A concentration reached 150-200 ng/ml. In both groups, azathioprine (150 mg/day) and prednisolone were given. During the first months, 6/15 grafts were lost in the OKT3 group (three hyperacute rejections, one renal vein thrombosis, one steroid-resistant rejection, one death); in the ALG group 4/23 grafts were lost (one hyperacute rejection, two steroid-resistant rejections, one death). Side effects were significantly more frequent in the OKT3 group than in the ALG group. After 12 months of follow up, the graft survival was 71% (27/38) and did not significantly differ (log-rank test, NS) between the OKT3 (60%, 9/15) and the ALG group (78%, 18/23). We conclude that the use of the monoclonal antibody OKT3 as a prophylactic agent in HSP does not improve the early graft survival when compared with prophylactic ALG. Polyclonal antibodies, which react with many epitopes and are much better tolerated seem to offer a good strategy for induction therapy in this population.

Adult↗
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↗
PubMed1994

[Kidney transplantation in patients more than 60 years old. Analysis of results apropos of 57 patients].

From April 1988 to August 1993, 57 elderly recipients more than 60 years old (mean age 64 +/- 3 years, 35 males, 22 females) underwent cadaveric renal transplantation. The pretransplant screening included immunological and viral status and urological examination; cardiovascular risk factors were systematically estimated by medical history, physical examination, echocardiography, femoral arterial doppler, and myocardial stress thallium imaging. A coronarography was performed if myocardial ischemia was evidenced. Patients free of cardiovascular diseases or after correction of vascular and/or coronary lesions were included in the waiting list. A sequential immunosuppression regimen including azathioprine, prednisolone anad antilymphocyte globulins was given in all patients. Oral cyclosporin A (5-8 mg/kg/day) was started when serum creatinine level decreased to 200 mumol/l; antilymphocyte globulins were stopped when whole trough blood cyclosporin level reached 150-200 ng/ml. After 24 months of follow-up, the patient survival rate of elderly recipients was significantly lower than the survival rate observed in patients less than 60 years old (90% vs 97%; p < 0.005); the deaths were related to cardiovascular complications in 3 cases and to infectious diseases in 3 cases. No abdominal complications were observed in our series. The graft survival was identical in both groups (81% vs 82% at 2 years), and we observed a low incidence of acute rejection (23%) in the elderly group. The graft function, as determined by serum creatinine level, is significantly correlated with the donor age (p < 0.05). We conclude that the patients more than 60 years old, free of ischemic coronary disease or after correction of such a lesion could be safely transplanted.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
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

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

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

Diagnostic methods for African horsesickness virus using monoclonal antibodies to structural and non-structural proteins.

A panel of 32 hybridoma cell lines secreting monoclonal antibodies (MAbs) reactive with African horsesickness virus serotype 4 (AHSV-4) has been developed. Four of the MAbs recognized the major core antigen VP7, twenty recognized the outer capsid protein VP2 and eight reacted with the non-structural protein NS1. With the VP7-specific MAbs a rapid and sensitive double antibody sandwich immunoassay has been developed to detect viral antigen in infected Vero cells and in spleen tissue from AHSV-infected horses. The sensitivity of the assay is 10 ng viral antigen per 100 microliters. The NS1-specific MAbs allowed visualization by immunofluorescence of tubule-like structures in the cytoplasm of infected Vero cells. This can be very useful as a confirmatory diagnostic procedure. The antigenic map of the outer capsid VP2 protein with MAbs is also reported.

African Horse Sickness↗