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M Lafon

Publications and source records attributed to M Lafon.

At least 55 records · Page 3Linked to original sources
PubMed1987

Localization and immunological characterization of antigenic domains of the rabies virus internal N and NS proteins.

To locate epitopes on internal antigens of rabies virus, purified N and NS proteins of the nucleocapsid were cleaved at methionine, tryptophan or glutamic acid residues, transferred to nitrocellulose and immunostained using monoclonal antibodies (MAbs) specific for N and NS proteins, respectively. Five MAb-positive fragments of N protein and one fragment of NS protein were located after NH2-terminal amino acid sequence analysis within the deduced amino acid sequences of N and NS proteins. Antigenic analysis of synthetic overlapping peptides corresponding to the amino acid sequences of these fragments localized two major antigenic sites of N protein and one antigenic site of NS protein. Like the N- and NS-specific MAbs, anti-peptide antisera produced against the different synthetic antigens either reacted in a type-common fashion with all rabies virus strains, or in a type-specific manner with a restricted number of strains. The synthetic peptides corresponding to the three antigenic regions of the N and NS proteins also stimulated proliferation of human T lymphocytes derived from vaccinees who received inactivated rabies virus vaccine. This suggested that the antigenic regions of N and NS proteins are recognized by both B and T cells.

Amino Acid Sequence↗
PubMed1987

Antiviral activity of monoclonal antibodies specific for the internal proteins N and NS of rabies virus.

Monoclonal antibodies (MAbs) specific for the rabies virus nucleoprotein (N protein) and non-structural (NS) protein of the nucleocapsid were introduced into adherent cells (fibroblasts and neuroblastoma) by the scrape-loading technique. After the cells had reattached to the substrate, they were infected with rabies virus. Inhibition of infection was monitored by measuring the intracytoplasmic viral nucleocapsid accumulation with an enzyme immunoassay using anti-N protein rabbit serum and by measuring the release of infectious virus with the plaquing system. Seventeen MAbs defining the three independent antigenic sites on the N protein were able to decrease nucleocapsid accumulation and the release of infectious virus. The MAbs describing the two antigenic sites on NS protein also had an antiviral effect on ERA virus. When an anti-N MAb (0.5 ng per cell) was introduced into CVS-infected cells, virus inhibition was complete if the anti-N MAb was introduced between 0 and 5 h post-infection and ineffective beyond 9 h post-infection. The inhibition was dose-dependent. The MAbs could block virus multiplication either by 'neutralizing' newly translated N and NS proteins or by impairing the initial transcription of the genome.

Antibodies, Monoclonal↗
PubMed1986

An evaluation of second generation tissue culture rabies vaccines for use in man: a four-vaccine comparative immunogenicity study using a pre-exposure vaccination schedule and an abbreviated 2-1-1 postexposure schedule.

In a double-blind comparative trial the immunogenicity of three new tissue culture rabies vaccines was evaluated, using a commercial human diploid cell vaccine (HDCV) lot as the reference. Two different vaccination regimens, a pre-exposure schedule, and an abbreviated 2-1-1 postexposure schedule (two doses of the vaccine applied bilaterally on day 0, with subsequent single doses given on days 7 and 21) were employed. In both, two of the new vaccines, purified chick embryo cell vaccine and purified Vero rabies vaccine, induced an antibody response equivalent to that of HDCV, while the geometric mean titres for the fetal bovine kidney cell vaccine were somewhat lower. The 2-1-1 regimen, a candidate regimen for economical rabies postexposure treatment, evoked a rapid and high titre antibody response with all four vaccines, peaking on day 14.

Adult↗
PubMed1985

Antigenic variants of CVS rabies virus with altered glycosylation sites.

The virion-associated glycoprotein of the CVS-11 strain of rabies virus exists in two forms, GI and GII, which differ in their carbohydrate content. The structural relationship between GI and GII is investigated in order to account for the difference in glycosylation. Partial sequence analysis and mapping of tryptic glycopeptides isolated from the parent CVS-11 GI and GII glycoprotein forms revealed that two of the three predicted glycosylation sites (at Asn-204 and Asn-319) were utilized in the GI form whereas only one of these two sites (at Asn-319) was utilized in the GII form. One predicted glycosylation site (at Asn-37) was not utilized in either species. In the variant virus, RV231-22, a single glycoprotein species was detected which corresponded in electrophoretic mobility to the GI form of the parent virus. Nucleotide sequence analysis of the variant glycoprotein gene revealed a base mutation which specifies an amino acid change six residues upstream from the predicted glycosylation site at Asn-204. This single amino acid substitution apparently results in utilization of the signal at Asn-204 in the GII form of RV231-22 virus. The amino acid substitution is discussed in relation to altered conformation. In the variant virus RV194-2 (F3), both GI and GII glycoprotein forms were present, but each revealed slower electrophoretic mobilities compared with the corresponding parent glycoprotein forms in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). An extra glycosylation site was identified in both glycoprotein forms of this variant virus.

Amino Acid Sequence↗
PubMed1985

Use of a monoclonal antibody for quantitation of rabies vaccine glycoprotein by enzyme immunoassay.

The use of a monoclonal antibody specific for the envelope glycoprotein of rabies virus has been used in a direct enzyme immunoassay to quantify the glycoprotein content of rabies vaccines produced in two kinds of cell culture. The results of this direct enzyme immunoassay are well correlated with the in vivo NIH potency test. This test may be a useful tool to rapidly and accurately control the antigenic value of a vaccine. It could also be used for the "in process' control of vaccine production before deciding whether a vaccine batch may reasonably be subjected to the NIH potency test.

Animals↗
PubMed1985

Antigenic sites on the ERA rabies virus nucleoprotein and non-structural protein.

Thirty-one monoclonal antibodies, specific for either the nucleoprotein (N) or the non-structural protein (NS; nucleocapsid-associated protein) of the nucleocapsid of the ERA strain of rabies virus, were used to investigate the topography of antigenic sites on the nucleocapsid complex. Based on the results of a competitive enzyme immunoabsorbent assay using these antibodies, five spatially distinct antigenic sites were defined: three on the N protein (groups N I, N II and N III) and two on the NS protein (groups NS I and NS II). Antigenic variations among various street and laboratory strains of rabies virus were analysed by indirect immunofluorescence assay with the monoclonal antibodies specific for the nucleocapsid. Some correlation between the natural nucleocapsid variation and the antigenic topographical map was observed.

Antibodies, Monoclonal↗
PubMed1984

Investigation of the antigenic structure of rabies virus glycoprotein by monoclonal antibodies.

Comparative antigenic analysis of glycoprotein variants of ERA and CVS-11 strains of rabies virus by monoclonal antibodies has permitted the delineation of three antigenic sites on the glycoprotein common to both strains. Two additional antigenic sites have been delineated on the ERA strain virus glycoprotein. The topologic relationship of these antigenic sites has been investigated.

Animals↗
PubMed1984

Characterization of rabies virus strains used for vaccine production by means of monoclonal antibodies.

A group of WHO Consultants who met in Geneva 16-18 September 1982, recommended, among other items, that "monoclonal antibody reactivity pattern of all viruses used for (rabies) vaccine production should be established" (WHO/Rab.Res./82.15) (1). Such a study has been undertaken in our WHO Collaborative Centre for Rabies in close collaboration with the WHO Collaborative Centre for Rabies of the Wistar Institute, and with monoclonal antibodies kindly supplied by T.J. Wiktor (2).

Animals↗
PubMed1984

Production of monoclonal antibodies against the Pasteur (P.V.) strain of rabies virus: problems and results.

Assuming the fact that the highest specific secreting hybrids number has been recorded with Iq secreting spleen cells, we did some immunizing protocols to maximize the ELISA reacting antibodies: for this Balb/c mice were primed intra-peritoneally with vaccine containing inactivated rabies (P.V. strain). Half of them were boosted intravenously with the same concentrated purified and live virus. We performed a series of hybridizations, at different times (i.e. 10, 15, 20, 75 days), between the rabies committed splenocytes and the SP 2/0 non secreting myeloma cells. Successful hybrids secreting antibody to rabies virus have only been obtained at the earliest and the latest time of fusion, essentially with the intravenous booster. They were initially screened by ELISA test for PV binding and about 65% of the colonies were generally positive. Clones directed against nucleocapsids were revealed by immunofluorescence of the rabies infected fixed cells, and those directed against glycoprotein by the neutralizing test and rabies infected live cells. From the early fusion we also produced hybrids secreting IgG (60%) or IgM (40%). At that time IgG/IgM distribution of specific hybrids do not correlate to that seen for ELISA reacting antibodies. It suggests that the IgG secreting spleen cells are the preferential fusion partners or the most vigorous ones.

Animals↗
PubMed1983

Characterization of an antigenic determinant of the glycoprotein that correlates with pathogenicity of rabies virus.

The pathogenicity of fixed rabies virus strains for adult mice depends on the presence of an antigenic determinant on the viral glycoprotein. Two virus-neutralizing monoclonal antibodies have been used to identify this determinant. All pathogenic strains of fixed rabies virus bind to these antibodies and are neutralized by them, whereas nonpathogenic strains fail to react with these monoclonal antibodies and are not neutralized by them. Antigenic variants of the rabies virus with altered glycoprotein were selected by growing virus in the presence of one monoclonal antibody, 194-2. All variants that lost their ability to react with this antibody and an additional antibody, 248-8, were found to be nonpathogenic for adult mice. Analysis of tryptic peptides of the glycoproteins of pathogenic parent virus and nonpathogenic variants and the amino acid sequence of a specific variant tryptic peptide revealed that the change in pathogenicity corresponded to an amino acid substitution at position 333 of the glycoprotein molecule. The nucleotide sequence of the nonpathogenic variant glycoprotein gene contained a base change that confirmed the single amino acid substitution in the tryptic peptide replacing arginine-333 in the parental glycoprotein. We conclude that arginine-333 is essential for the integrity of an antigenic determinant and for the ability of rabies viruses to produce lethal infection in adult mice.

Amino Acid Sequence↗
PubMed1983

Antigenic sites on the CVS rabies virus glycoprotein: analysis with monoclonal antibodies.

Antigenic variation in the glycoprotein of rabies (CVS-11) virus was studied. Neutralization-resistant variant viruses were isolated in vitro at high frequency (10(-4) to 10(-5)) in the presence of anti-glycoprotein monoclonal antibody. Analysis of these variants identified at least three functionally independent antigenic sites, based on the grouping of variants that were no longer neutralized by one or more of a panel of 24 monoclonal antibodies. Competition radioimmunoassay suggested that one of these three antigenic sites was topologically distinct, with the other two in close proximity. In addition, it was shown that most (but not all) neutralization-resistant variants failed to bind the relevant monoclonal antibody. Viruses with altered antigenicity were shown to accumulate in virus stocks following several passages in vitro in the absence of antibody. In addition, variants were isolated in vivo following treatment of mice with monoclonal antibody.

Antibodies, Monoclonal↗
PubMed1977

[Comparative anatomical result of conservative treatment and surgery in severe recent sprains of the ankle (author's transl)].

Severe recent sprains involving the lateral ligament of the ankle have been the object of numerous publications in recent years. Most authors have recommended the extension of the indications for open surgery. This lesion which was previously treated by immobilisation or even immediate physiotherapy is now operated on by numerous surgeons. In view of the very subjective character of the patient's opinion, and of the opinion of surgeons, it seemed logical to compare the radiological result in two series of similar severity operated on or treated by simple plaster immobilisation. One may note that the results observed are very similar, even when the accident gives rise to considerable separation of the tibio-talus joint line. Perhaps the figures published here will contribute to make surgery less often indicated.

Adult↗
PubMedDate not supplied

A reduced panel of anti-nucleocapsid monoclonal antibodies for bat rabies virus identification in Europe.

A reduced panel of 4 anti-nucleocapsid monoclonal antibodies (mAb) was set up to distinguish viruses of terrestrial mammal origin from viruses of bat origin in Europe. Four additional mAb were necessary to identify each one of the four serotypes of lyssavirus. These 8 mAb were selected out of 25 mAb secreted by hybridomas obtained from mice immunized with either serotype 1 lyssavirus (rabies virus PV4) or serotype 3 lyssavirus (Mokola). They were screened with 32 viruses representative of the four lyssavirus serotypes and the two types of European bat lyssavirus. The panel was tested by immunofluorescence assay with 25 cell-culture-adapted European wildlife isolates and in routine rabies identification with 65 rabid animal brain smears. Two isolates from Eptesicus serotinus in France were identified as European bat lyssavirus 1 with the reduced panel.

Animals↗