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Biomedical subjects

A Osterhaus

Publications and source records attributed to A Osterhaus.

At least 19 recordsLinked to original sources
PubMed1994

Enzyme immunoassay (ELISA) for the evaluation of antibodies directed to the CD4 receptor-binding site of the HIV gp120 molecule.

The interaction between the HIV envelope glycoprotein gp120 and the CD4 molecule is probably the most important primary event determining HIV infection. Reactivity with the native viral envelope has been difficult to measure due to the lack of gp120 ligand purified directly from primary virus cultures. We have developed an ELISA, utilizing Galanthus nivalis agglutinin (GNA) which selectively binds native HIV envelope gp120 in culture medium. The GNA-based ELISA eliminates the need for isotope-labelled reagents, live cells and recombinant non-natively glycosylated envelope proteins and offers an easy way of using gp120 directly from crude HIV culture medium. The reactivities of sera from several categories of HIV infected individuals were assayed for inhibition of the HIV-1 gp120-CD4 binding. 19/32 (59.3%) sera from asymptomatic individuals and 7/10 (70%) sera from ARC/AIDS patients blocked the CD4-gp120 binding. 20 serum samples from uninfected individuals showed a gp120-CD4 interaction blocking capacity of 0-15%. Two monoclonal antibodies, T4.2 directed to CD4 and 1171 directed to the CD4 binding site of gp120 were used as positive controls. Both Mabs inhibited CD4-gp120 binding by 66-90%.

Adolescent↗
PubMed1993

Neutralizing antibodies in cats infected with feline immunodeficiency virus.

Sera from cats experimentally infected with five isolates of feline immunodeficiency virus (FIV) from various geographical regions and from FIV enzyme-linked immunosorbent assay-seropositive field cats from four European countries neutralized the Petaluma strain of FIV (FIV-P), originally isolated in California, at high titers. In addition, FIV-P and a European isolate proved equally susceptible to neutralization by all sera tested. Coupled with observations by Fevereiro et al. (M. Fevereiro, C. Roneker, A. Laufs, L. Tavares, and F. de Noronha, J. Gen. Virol. 72:617-622, 1991), these findings indicate that most if not all FIV strains circulating in Europe and the United States share important neutralization-inducing epitopes.

Animals↗
PubMed1992

An immune stimulating complex (ISCOM) subunit rabies vaccine protects dogs and mice against street rabies challenge.

Dogs and mice were immunized with either a rabies glycoprotein subunit vaccine incorporated into an immune stimulating complex (ISCOM) or a commercial human diploid cell vaccine (HDCV) prepared from a Pitman Moore (PM) rabies vaccine strain. Pre-exposure vaccination of mice with two intraperitoneal (i.p.) doses of 360 ng ISCOM or 0.5 ml HDCV protected 95% (38/40) and 90% (36/40) of mice, respectively, against a lethal intracerebral (i.c.) dose with challenge virus strain (CVS). One 360 ng i.p. dose of ISCOM protected 87.5% (35/40) of mice against i.c. challenge with CVS. Three groups of five dogs were vaccinated intramuscularly (i.m.) with 730 ng of rabies ISCOM prepared from either the PM or the CVS rabies strains, and they resisted lethal street rabies challenge. Postexposure treatment of mice with three or four 120 ng i.m. doses of ISCOM protected 90% (27/30) and 94% (45/48), respectively, of mice inoculated in the footpad with street rabies virus, but three doses of HDCV conferred no protection. When four doses of HDCV were administered postexposure, 78% (32/41) of the mice died of anaphylactic shock; 21% (11/52) of mice had already died of rabies 4 days after the third vaccine dose was administered.

Animals↗
PubMed1992

Comparison of protection afforded by whole virus ISCOM versus MDP adjuvanted formalin-inactivated SIV vaccines from IV cell-free or cell-associated homologous challenge.

A SIV-ISCOM and a SIV-MDP adjuvanted vaccine were tested for their potential to induce protection from intravenous cell-free or cell-associated homologous SIV challenge in rhesus monkeys (Macaca mulatta). Seven monkeys vaccinated four times over a four-month period with either the SIV-ISCOM or the SIV-MDP vaccine were challenged intravenously with approximately 10 MID50 cell-free SIVmac251 (32H). They all were protected from developing viremia during a three-month observation period. Two other groups of four monkeys were vaccinated essentially in the same way with either of these vaccines. They were challenged intravenously with approximately 10 MID50 of infected PBMC of a rhesus monkey that had been infected with SIVmac251 (32H) 11 months earlier (stock prepared by J. Heeney). Two monkeys of each of these two groups proved to be protected from developing viremia during a two-month observation period. For both the cell-free and the cell-associated SIV challenge, monkeys vaccinated with measles virus ISCOMS or MDP adjuvanted measles virus antigen, served as controls. They all became viremic within two weeks after SIV challenge. This is the first demonstration that vaccinated previously unchallenged nonhuman primates can be protected from infection with lentivirus-infected PBMC from another animal. Serological analysis indicated that SIV-specific serum antibody titers were considerably higher in SIV-ISCOM vaccinated animals than in the SIV-MDP vaccinated animals. The serology also confirmed the protection data, by showing the absence of increase in SIV-specific serum antibodies in apparently protected animals after challenge.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1992

[The humidification of anesthetic gases during anesthesia using heat and moisture exchangers].

This study looks at the question of whether anaesthetic gases are sufficiently moistened in a semi-closed system by the partial recycling of expired air with simultaneous absorption of CO2. During the inspiration phase only a maximum of 42% relative humidity at a temperature of 24.8 degrees C was reached. These values lie far below the demands of the American National Standard Institute (ANSI) of 70% relative humidity at 30 degrees C. When various heat and moisture exchangers were used, the relative humidity improved to 99% at a maximum temperature of 30.3 degrees C (HME Edith; Engström Corporation). The maximum values of the BB 12-15, Pall Corporation, and SH 150 from Siemens were slightly lower. A marked fall was noticed when using the Humid Vent I of the Medimex Corporation, especially in the initial phase. An improved version, the Humid Vent II, has been produced. Physiological values (37 degrees C, 100% relative humidity) are not achieved by any heat and moisture exchangers. This problem could possibly be solved by using infra-red light when warming the gases.

Anesthesia, Inhalation↗
PubMed1991

Maintenance of immunological memory: a role for CD5+ B cells?

How memory is retained is an immunological mystery. One possibility, argued here by Fons UytdeHaag and colleagues, is that memory is imprinted in the somatically-mutated Ig expressed by certain CD5+ B cells. The theory proposes that the Ig expressed by this self-renewing population acts as surrogate antigen, selecting and stimulating emerging antigen-specific lymphocytes.

Animals↗
PubMed1990

Rabies virus cross-reactive murine T cell clones: analysis of helper and delayed-type hypersensitivity function.

Three T cell clones derived from rabies virus-immunized BALB/c mice were analysed for specificity and function. The clones proved to be broadly cross-reactive by responding to different rabies virus isolates (PM, ERA, CVS, HEP) and other representatives of the genus Lyssavirus, like the Duvenhage-6 (DUV6) and Mokola (MOK) viruses. The clones detected three different epitopes: an epitope expressed on the matrix protein (M) shared by PM, HEP, MOK and DUV6 viruses (clone AA8), an epitope expressed on the M-protein shared by PM, ERA, CVS, HEP and MOK viruses (clone 35A) and finally an epitope expressed on the glycoprotein (G-protein) shared by PM, ERA, CVS, HEP and MOK viruses (clone BG2). Antigen recognition of all clones proved to be MHC-restricted and they all displayed the CD4+ CD8- phenotype. Intravenous inoculation of the T cells in syngeneic mice, which had been injected intracutaneously in the ear with HEP virus, resulted in a localized DTH reaction characteristic for TH1 cells. In vitro, the clones were able to provide help to rabies virus-primed B cells, resulting in the production of virus-specific antibodies directed against all the four structural proteins of rabies virus. Further analysis of this antibody response revealed that part of it was directed against antigenic determinants of the G-protein which induce virus neutralizing antibody.

Animals↗
PubMed1990

Comparison of enzyme-linked immunosorbent and virus neutralization assays for the serology of reovirus infections in laboratory animals.

An enzyme-linked immunosorbent assay (ELISA) for the detection and quantification of reovirus-specific IgM and IgG serum antibodies in rodents, detecting reovirus group reactive antibodies, was compared with reovirus types 1, 2 or 3 specific virus neutralization (VN) assays. To this end, serum samples were collected from specific pathogen-free (SPF) BALB/c RIVM mice, after experimental infection with any of the three mammalian reovirus serotypes. The majority (seven out of twelve) of the reovirus type 1-infected and one third (two out of six) of the reovirus type 3-infected mice died within 15 days after infection, whereas all (six out of six) of the reovirus type 2-infected animals survived. Using reovirus type 2 antigen in the ELISA, reovirus-specific IgM antibodies could be demonstrated within 1 week after infection in all the mice infected with reovirus types 2 or 3 and in the majority of the mice infected with type 1. Similarly, reovirus-specific IgG could be detected within 3 weeks in all the surviving mice infected with reovirus types 2 or 3 and within 5 weeks in all surviving mice infected with reovirus type 1. These results coincided well with the data obtained in the VN assays, in which all the infected animals also could be detected within 1 week after infection. As expected, titers were detected most rapidly and to the highest levels in the homologous VN assays. Given the sensitivity and the specificity of the ELISA system demonstrated in this paper and its suitability for incorporation in automated systems, the ELISA system should be considered valuable for the routine serologic diagnosis of reovirus infections in rodents.

Animals↗
PubMed1989

Comparison of immunofluorescence and enzyme-linked immunosorbent assays for the serology of Hantaan virus infections.

Three enzyme-linked immunosorbent assay (ELISA) systems based upon different principles were developed for the serology of Hantaan virus infections and compared with an indirect immunofluorescence assay (IFA). The indirect IFA was carried out with gamma-irradiated Hantaan virus-infected and uninfected Vero E6 cells fixed with ethanol (-70 degrees C) or acetone (20 degrees C) on drop slides and a FITC-coupled sheep anti-human Ig preparation. Atypical staining in the IFA was avoided by using ethanol (-70 degrees C) instead of acetone (20 degrees C) fixation. In the first ELISA ('cell-assay'), Hantaan virus-infected or uninfected Vero E6 cells were used as antigens, which after gamma-irradiation were seeded into microtiter ELISA strips. Serial dilutions of human sera were incubated and specific antibodies were demonstrated with a horseradish peroxidase (HRPO)-conjugated sheep anti-human Ig preparation. In the second ELISA ('competition-assay') an affinity-purified human Ig preparation was used as a capture antibody for Hantaan virus antigen. After incubation of serial dilutions of human sera with this coat, the reactivity of the affinity purified anti-Hantaan virus Ig coupled to HRPO was determined. In the third ELISA ('complex trapping blocking [CTB]-assay') the same capture antibody was used to react with a mixture of the antigen and serial dilutions of human sera. The reactivity with the same HRPO conjugate was then determined. The results obtained in the respective assay systems with sera from people at risk or suspected of Hantaan virus infection coincided well. The CTB-ELISA proved to be faster and more sensitive than both the other ELISA systems, without giving more non-specific reactions: it detected almost all the IFA positive samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Serological responses in cats vaccinated with FeLV ISCOM and an inactivated FeLV vaccine.

Various approaches have been considered for generation of effective and safe vaccines against retroviruses, including HIV, with limited success. In the present vaccination study, encompassing 137 household cats, we have composed an experimental ISCOM subunit vaccine containing gp70 of feline leukaemia virus (FeLV)--the external glycosylated envelope protein, and the transmembrane protein p15E, with a commercial available inactivated FeLV vaccine (Leukocell). The two vaccines were estimated to contain approximately the same amount of gp70 antigen and the cats were immunized three times according to the recommendations of the commercial vaccine. A control preparation not containing gp70 or p15E was also included. During the observation period of 200 days all cats remained healthy and no virus was isolated during the isolation attempts. The serological responses were measured in ELISA, membrane immunofluorescence (MIF) and virus neutralization (VN) tests. In contrast to the cats in the other groups almost all ISCOM-vaccinated cats responded by seroconversion or increased titres in the three tests. The development of specific antibodies to gp70 and p15E were confirmed in Western blot. These results clearly illustrate the potential of the ISCOM structure for the development of safe and effective vaccines against retroviruses.

Animals↗
PubMed1989

Formation and characterization of FeLV ISCOMs.

Immunostimulating complexes (ISCOMs) have been prepared from feline leukaemia virus (FeLV) envelope proteins. The ISCOMs were characterized biochemically in SDS-polyacrylamide gel electrophoresis showing the presence of proteins of estimated molecular weights of 15,000, 27,000 and 70,000. Immunoblotting showed that both the transmembrane protein p15E and the external glycoprotein gp70 (making up the gp85 protein) were present in the ISCOM. Furthermore, a degradation product of gp70 with an estimated molecular weight of 32,000 was identified in the immunoblot. The FeLV ISCOM was shown by electron microscopy to have the characteristic cage-like structure of an ISCOM with a mean diameter of 37 nm. About 10% of the total amount of gp70 in the culture fluid was recovered in the ISCOMs. The largest loss was encountered during the sedimentation of the virus. In a preliminary immunization experiment in mice the FeLV ISCOMs elicited after a booster gave a clear-cut immune response against gp70.

Animals↗
PubMed1989

A morbillivirus causing mass mortality in seals.

During an outbreak of a serious apparently infectious disease among harbour seals (Phoca vitulina), which started in the Kattegat area in April 1988 and rapidly spread to the North sea, the Wadden sea and the Baltic sea, greater than 17,000 animals died within a period of eight months. In August 1988 it was realized that the clinical symptoms and pathological lesions were similar to those found in canine distemper: apart from general depression and fever, the animals suffered from severe respiratory, gastrointestinal and central nervous disease and a variety of viral, bacterial and parasitic infections were frequently encountered, suggesting a severe malfunctioning of the immune system. At different expert meetings, held in several of the countries involved, possible explanations for the deaths were not only attributed to an infectious agent, but also to effects of overpopulation and environmental pollution. Seroepizootiological studies and the failure of vaccination experiments suggested that a herpesvirus and a picornavirus, which had been isolated from dead seals at the beginning of the outbreak, were opportunistic infections occurring in animals suffering from another infection rather than being the primary cause of the outbreaks. Serological studies were then extended to other viruses of carnivores, known to cause similar symptoms. Screening of a large panel of seal sera from the Netherlands, Denmark, FRG, Sweden and the UK, collected before and during the outbreak, in a virus neutralization test for the presence of canine distemper virus (CDV) neutralizing antibodies, indicated that CDV or a closely related morbillivirus was the primary cause of the disease outbreak.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Comparison of an enzyme-linked immunosorbent assay, an immunofluorescence assay and a hemagglutination inhibition assay for detection of antibodies to K-papovavirus in mice.

The sensitivity of a newly developed enzyme-linked immunosorbent assay (ELISA) for detection of antibody to K virus was compared with the sensitivities of an immunofluorescence assay (IFA) and a hemagglutination inhibition assay (HIA). Specific pathogen-free BALB/c RIVM mice, 5 weeks old, were inoculated intraperitoneally with a mouse organ suspension containing 10(4.5) TCID50 of K virus per dose. Control animals were inoculated with a control mouse organ suspension. No clinical signs were observed during the 7 weeks they were followed for the development of serum antibody. The ELISA proved to be the most sensitive of the three assays and demonstrated K virus-specific antibodies as early as 3 days after infection.

Animals↗