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Biomedical subjects

A L van Wezel

Publications and source records attributed to A L van Wezel.

At least 19 recordsLinked to original sources
PubMed1992

Serological and virological assessment of oral and inactivated poliovirus vaccines in a rural population in Kenya.

A study was carried out in a rural community in Kenya to compare the humoral and intestinal immunity provided by three doses of oral poliovirus vaccine (OPV) and two or three doses of enhanced-potency inactivated poliovirus vaccine (IPV). The immunization series was started at 8-12 weeks of age and the interval between doses was 2 months. In children with low levels of maternal antibodies (i.e., those most at risk), the first dose of either vaccine stimulated antibody response. Children with high levels of maternal antibodies responded to the first dose of OPV, but not to that of IPV. Subsequent doses led to increases in the mean antibody titres with both vaccines. After three doses of OPV, the proportion of children with antibody titres of greater than or equal to 1:8 was 92% for type 1 virus, 98% for type 2, and 90% for type 3. After two doses of IPV the proportion of children with antibody titres of greater than or equal to 1:8 was 94%, 88%, and 97% for type 1, type 2, and type 3, respectively; after three doses of IPV, 100% of children had antibodies greater than or equal to 1:8 for types 1 and 3, and 98% for type 2. Intestinal immunity was tested with a challenge dose of type 1 OPV, but the dose used was too small to detect a significant difference between the vaccines.

Antibodies, Viral↗
PubMed1988

Measles virus fusion protein presented in an immune-stimulating complex (iscom) induces haemolysis-inhibiting and fusion-inhibiting antibodies, virus-specific T cells and protection in mice.

Immune-stimulating complexes (iscoms), which have recently been shown to be highly effective for the antigenic presentation of membrane proteins of viruses, were prepared with affinity-purified fusion (F) protein of measles virus (MV), using an adaptation of the standard method for iscom preparation. Immunization of monkeys with the F iscom preparation induced biologically active anti-F protein antibodies as was shown in haemolysis inhibition and cell-cell fusion inhibition tests. A whole MV iscom preparation, which also contained the haemagglutinin protein, induced not only also haemolysis-inhibiting antibodies, but, in contrast to the F iscom preparation, also haemagglutination-inhibiting and virus-neutralizing antibodies. In addition the F iscom preparation was shown to activate measles virus-specific T cells in mice. This was demonstrated by the generation of an MV-specific delayed type hypersensitivity response in F iscom-immunized animals and by the isolation of T cell clones specific for MV F protein with the T helper phenotype. Vaccination of mice with MV iscom or F iscom protected them from MV-induced fatal encephalopathy. The data concerning the immunogenicity of MV proteins presented in iscoms are discussed in relation to their potential for the development of an inactivated measles vaccine.

Animals↗
PubMed1986

Characterization and fibrin-binding properties of different molecular forms of pro-urokinase from a monkey kidney cell culture.

Culture fluid of a monkey kidney cell culture was harvested every two days, for a two week period, in order to obtain urokinase in the zymogen form. Pro-urokinase was isolated by immunoadsorption chromatography and gel filtered on Sephadex G-150, which resulted in three peaks with pro-urokinase activity. SDS-polyacrylamide gel electrophoresis showed that the first peak contained 55 kd pro-urokinase, aggregated with high molecular weight contaminants, whereas the second and third peaks consisted of almost pure 55 kd and 30 kd pro-urokinase, respectively. The latter form represented a relatively unknown and inactive precursor of low molecular weight urokinase, which was, like 55 kd pro-urokinase, activatable with plasmin. In comparison with tissue-type plasminogen activator, 55 kd and 30 kd pro-urokinase only bound weakly to purified fibrin clots and fibrin-sepharose columns. The extent of binding of the two pro-urokinases and their plasmin-activated forms to fibrin-sepharose decreased in the following order: 55 kd pro-urokinase 30 kd pro-urokinase 55 kd urokinase 30 kd urokinase. These results indicate that the two precursors exhibited stronger binding to fibrin-sepharose than the corresponding active enzymes, and the two 55 kd forms exhibited stronger binding than the corresponding 30 kd forms. This indicates the importance of both the zymogen nature and an intact NH2-terminal part of the molecules for binding to fibrin.

Animals↗
PubMed1985

Large scale animal cell cultivation for production of cellular biologicals.

Through the developments in molecular biology the interest for large scale animal cell cultivation has sharply increased during the last 5 years. At our laboratory, four different cultivation systems were studied, all of which are homogeneous culture systems, as they lend themselves best for scaling up and for the control of culture conditions. The four different systems which were compared are: batch culture, continuous chemostat, continuous recycling and continuous perfusion culture system, both for cells growing in suspension and for anchorage dependent cells in microcarrier culture. Our results indicate that for the production of virus vaccines and cells the batch and recycling culture system are most suitable. Disadvantages of the continued chemostat culture system are: the system is only applicable for cells growing in suspension; relatively low concentrations of cells and cellular products are obtained. The continuous perfusion system appears to be very suitable for the production of cellular components and also for the production of viruses which do not give cell lysis.

Animals↗
PubMed1984

Induction of long-term immunity to paralytic poliomyelitis by use of non-infectious vaccine.

Naturally acquired immunity to paralytic poliomyelitis, which is of long duration, is associated with serum antibody, immunological memory, or both. Persistence of circulating antibody is reassuring but not essential for long-term protection. Immunological memory induced by killed poliovirus vaccine is similar to that induced by infection, which is not a prerequisite for the induction of long-term immunity. Animal studies of experimental vaccines indicate that some antigenic components of poliovirus induce immunological memory without producing detectable antibody; killed poliovirus vaccine has the same effect in man. Killed vaccine containing 40, 8, and 32 D-antigen units of poliovirus types 1, 2, and 3, respectively, protects all recipients in both one-dose and two-dose schedules. This means that either schedule can be chosen to fit in with local immunisation programmes and thus reduce costs and increase population coverage.

Antibodies, Viral↗
PubMed1984

[Biotechnology and vaccine manufacture].

Modern biotechnology offers great possibilities for the large-scale manufacture of effective, safe and inexpensive vaccines. Improvements can also be expected in the manufacture of traditional vaccines, and there would appear to be prospect of producing vaccines against (tropical) parasitic disease for the first time. Close cooperation between university centres, research institutes and industry is essential to the development of biotechnology.

Netherlands↗
PubMed1984

The evaluation of a physical method for the quantification of inactivated poliovirus particles and its relationship to D-antigenicity and potency testing in rats.

The use of a density gradient procedure for the quantification of intact, inactivated poliovirus particles in vaccine preparations is described. The procedure is both sensitive and highly reproducible and the results correlate with those of potency tests in rats and with D-antigen content as measured by ELISA. Because of the occasional ambiguity observed with D-antigen assays, it is suggested that the density gradient procedure will provide valuable additional information for the in vitro assessment of inactivated poliovirus preparations.

Animals↗
PubMed1984

Strain differentiation of polioviruses with monoclonal antibodies.

Panels of monoclonal antibodies raised against different poliovirus type 1, 2 and 3 strains, were tested in a micro-neutralization test and in a micro-enzyme linked immunosorbent assay against a large number of poliovirus strains. The results were compared with those obtained with the classical system of serodifferentiation using strain specific cross-absorbed antisera. For this purpose a theoretical pattern fitting computer program was developed, in which each strain could be compared with all the other strains of which the serological data had been stored in the memory of the computer. The results obtained with the panels of monoclonal antibodies coincided well with those obtained with the cross-absorbed antisera. Especially for the identification of virus isolates related to the Sabin vaccine strains, these panels of monoclonal antibodies proved to be valuable tools.

Animals↗
PubMed1983

A modified ELISA technique for the titration of antibodies to polio virus as an alternative to a virus neutralization test.

An ELISA based on inhibition of antibody binding for the determination of antibodies to polio virus type I is described. F(ab1)2-fragments of bovine antibodies to polio virus type I are used as the capture antibody thus lowering the background staining. A good correlation was found between the poliovirus neutralizing antibody level and the antibody titers as determined by ELISA.

Animals↗
PubMed1983

Induction of neutralizing antibodies by poliovirus capsid polypeptides VP1, VP2 and VP3.

The antigenic and immunogenic properties of poliovirus capsid polypeptides (VPs) have been investigated in vivo and in vitro. VPs were isolated from infectious and formalin inactivated virus. Upon immunization VPs from infectious virus did not induce neutralizing antibodies in laboratory animals after two or three injections. Monomeric VP1, VP2 and VP3 from formalin inactivated virus all induced high titres of neutralizing antibodies generally already after two injections. Some anti-VP sera neutralized heterologous virus types. All anti-VP sera reacted with the corresponding capsid polypeptides from the homologous and heterologous virus strains in an immunoblotting assay. The anti-VP sera reacted equally well with D- and C-antigen in ELISA. Our results indicate that not only VP1, but also VP2 and VP3 are involved in the induction of neutralizing antibodies.

Animals↗
PubMed1983

Monoclonal antibodies to polioviruses. Comparison of intratypic strain differentiation of poliovirus type 1 using monoclonal antibodies versus cross-absorbed antisera.

A panel of 10 monoclonal antibodies raised to 3 different poliovirus type 1 strains was tested in a micro-enzyme-linked immunosorbent assay and in a micro-neutralization test against 87 poliovirus type 1 strains. The results, evaluated in a newly developed system for intratypic strain characterization, were compared with the results obtained with the classical sero-differentiation system by using a small number of strain-specific, cross-absorbed antisera. The new system not only uses results obtained with strain-specific antibody preparations, but also uses the information obtained with monoclonal antibodies reacting with less unique antigenic determinants. In a theoretical pattern fitting computer program, each virus strain could be compared with all the other strains for which serological data were stored in the memory of the computer. The results obtained with the new system coincided well with those obtained with the classical system: all except one of the strains classified as Sabin-like or intermediate in the classical system scored 'perfect fit' or 'related' with the Sabin 1 vaccine strain in the new system. Likewise, all virus isolates classified as Kuwait-like in the classical system scored 'perfect fit' or 'related' with the Dutch Kuwait-like isolate strain 78-9030.

Animals↗
PubMed1983

Antigenicity and immunogenicity of poliovirus capsid proteins.

Poliovirus capsid proteins (VP's) were isolated by DEAE-Sepharose chromatography in the presence of RNA-se and 9 M urea or by preparative SDS-polyacrylamide gelelectrophoresis (SDS-PAGE). With the first method, several, but not all, capsid proteins, from the three different virus types could be isolated in pure form, probably because of incomplete dissociation of the virus particles in 9 M urea. With SDS-PAGE all capsid proteins could be isolated in pure form. Immunization of rats and rabbits with the three largest VP's (VP1, VP2 and VP3) isolated by both methods, resulted in the induction of neutralizing antibodies already after 2-3 injections, provided the capsid proteins were isolated from formalin inactivated virus. Apparently formalin treatment stabilized the antigenic determinants, which are responsible for induction of neutralizing antibodies, against denaturation upon VP-isolation. In contrast to several other picornaviruses, where only one of the VP's induces neutralizing antibodies, for poliovirus both VP1, VP2 and VP3 are able to induce neutralizing antibodies. VP's isolated from live virus did not induce neutralizing antibodies, but were able to "prime" the animals. Primary vaccination with any of the VP's, followed by a second injection with a low dose of vaccine (D-antigen) resulted in a boosterlike production of neutralizing antibodies against the D-antigen, even D-antigen of a heterotypic virus. This indicates the occurrence of common antigenic regions on the different capsid polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Antigen content of inactivated poliovirus vaccine for use in a one- or two-dose regimen.

The immunologic response to inactivated poliovirus vaccine following one and two doses has been studied in infants in developing and developed countries using vaccine prepared at the Rijks Instituut voor de Volksgezondheit, The Netherlands. Virus was grown in microcarrier cultures of monkey kidney cells, purified, concentrated, and inactivated with formalin. The vaccines used contained different quantities of D-antigen units for each of the three types. The data reveal that both antibody and immunologic memory (booster-type responsiveness) were induced in virtually all individuals following a single dose of a sufficient quantity of antigen. Immunologic memory was readily revealed by the booster-type response following a second dose given six months after the first. The degree of booster-type response to a second dose is linked primarily to the quantity of antigen used for primary immunization, and secondarily to the quantity of antigen used for the booster dose. The data base is presented for formulating the antigen content of an inactivated poliovirus vaccine that can be relied upon to be protective after the first dose when given alone or when incorporated with combinations of other antigens (diphtheria-per tussis-tetanus) that may require two or more doses.

Antibody Formation↗