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M P Koopmans

Publications and source records attributed to M P Koopmans.

31 records · Page 2Linked to original sources
PubMed1998

Age-stratified seroprevalence of neutralizing antibodies to astrovirus types 1 to 7 in humans in The Netherlands.

Astroviruses are a new family of positive-stranded RNA viruses that cause gastroenteritis in a wide range of animals and in humans. Seven types of astrovirus, tentatively considered serotypes, have been distinguished by enzyme-linked immunosorbent assays (ELISA) or immunoelectron microscopy, but it is unclear whether the serotype designation is used properly. To test human sera for the presence of neutralizing antibodies and to type field strains, neutralization tests (NT) using CaCo2 tissue-culture-adapted astrovirus strains 1 to 7 and the corresponding rabbit reference sera were developed. In rabbits, neutralizing antibodies were predominantly serotype specific, with the exception of low-level cross-reactivity in astrovirus serotype 4 reference serum with astrovirus serotype 1 virus. Similarly, in humans, no evidence of cross-reactivity was found for the serotype combinations tested (all except the combination 1 and 7 and the combination 6 and 7). Typing by NT was concordant with typing by ELISA and genotyping, with one exception. The seroprevalence rates of neutralizing antibodies in an age-stratified sample of the population in Utrecht Province (n = 242) were 91% for astrovirus serotype 1, 69% for astrovirus serotype 3, 56% for astrovirus serotype 4, 36% for astrovirus serotype 5, 31% for astrovirus serotype 2, 16% for astrovirus serotype 6, and 10% for astrovirus serotype 7. Acquisition of antibodies was slower among persons seropositive for astrovirus serotype 5 than among those seropositive for astrovirus serotypes 1 to 4, suggesting that the epidemiology of serotype 5 astrovirus is different from that of astrovirus serotypes 1 to 4.

Adolescent↗
PubMed1997

Genetic analysis of wild-type poliovirus importation into The Netherlands (1979-1995).

Wild polioviruses were isolated a number of times in The Netherlands outside the epidemic periods (1978 and 1992-1993) from patients infected abroad, from subclinically infected persons, and from river water. Sequence comparisons revealed discrete sources of importation: the Mediterranean, India, and Indonesia. The observed wide genetic variation is indicative of repeated importation and not of indigenous circulation. Isolates identical or closely related to the epidemic type 1 strain of 1978 were found in clinical and environmental specimens until 1983, probably due to repeated importation from Turkey. Viruses related to the 1992-1993 epidemic type 3 virus had already been isolated six times before the epidemic. Of particular importance are two documented isolations of prototype wild poliovirus indistinguishable from that used to produce the inactivated vaccine. These data underscore the continued risk to the unvaccinated religious population of exposure to wild poliovirus.

Adoption↗
PubMed1997

The incidence and genetic variability of small round-structured viruses in outbreaks of gastroenteritis in The Netherlands.

Small round-structured viruses (SRSV) are a group of RNA viruses that can cause gastroenteritis in persons of all ages. To determine the incidence of SRSV-associated gastroenteritis in The Netherlands and to study the genetic variability of outbreak strains, all outbreaks that were reported to the epidemiologists of the regional health services in 1996 were investigated using a standardized protocol. In 60 (87%) of the 69 reported outbreaks, SRSV could be detected, showing the etiologic significance of SRSV in outbreaks of gastroenteritis in The Netherlands. Of these outbreaks, 84% occurred in semiclosed communities, such as nursing homes (59%) and hospital wards (25%). Sequence analysis of the outbreak strains revealed that the majority of the strains from January to November 1996 formed a tight cluster within genogroup II SRSV. In November 1996, a shift toward genogroup I SRSV occurred, suggesting a change to a new predominant strain.

Age Factors↗
PubMed1997

Association of torovirus with acute and persistent diarrhea in children.

OBJECTIVE: To study the etiologic role of toroviruses as a cause of gastroenteritis in humans. METHODS: The design was a case-control study. We compared the rate of torovirus detection in fecal specimens from a selection of children with acute or persistent diarrhea and controls without diarrhea from a study of childhood diarrhea in an urban Brazilian slum. Stool samples were coded and tested in a blinded fashion for the presence of torovirus antigen by enzyme-linked immunosorbent assay, other enteropathogens, toxins and fecal leukocytes. RESULTS: Thirty-three children with acute diarrhea, 41 children with persistent diarrhea and 17 controls were enlisted in the study. Torovirus antigen was detected in 9 (27%) samples from children with acute diarrhea, 11 (27%) samples from children with persistent diarrhea and none of the samples from controls (P < 0.05). In addition the presence of enteroaggregative E. coli was associated with persistent diarrhea and the presence of Cryptosporidium oocysts was common although not significant (P = 0.08); torovirus and Cryptosporidium occurred in different subsets of samples, whereas torovirus and enteroaggregative Escherichia coli were commonly found in combination. CONCLUSIONS: These data indicate that toroviruses, alone or in combination with enteroaggregative E. coli, may play a pathogenic role in acute and possibly persistent diarrhea. Further studies are warranted to determine the etiologic role of toroviruses in gastroenteritis.

Acute Disease↗
PubMed1997

Poliovirus-specific immunoglobulin A in persons vaccinated with inactivated poliovirus vaccine in The Netherlands.

In The Netherlands the inactivated poliovirus vaccine (IPV) is used for protection against poliomyelitis. It is not clear if parenteral vaccination with IPV can lead to priming of the mucosal immune system. We developed and evaluated enzyme-linked immunosorbent assays for the detection of poliovirus serotype-specific immunoglobulin A (IgA) and secretory IgA antibodies. Using these assays we examined the kinetics of the IgA response in sequential serum samples from 15 poliomyelitis patients after natural infection with serotype 3 poliovirus. In 36% of the patients IgA remained present for up to 5 months postinfection. Furthermore, we examined, in an IPV-vaccinated population, the presence of IgA antibodies in sera from young children (4 to 12 years of age; n = 177), sera from older children (between 13 and 15 years of age; n = 123), sera from healthy blood donors (n = 66), and sera from naturally immune elderly persons (n = 54). The seroprevalence of IgA to all three serotypes was low in young vaccinated children (5 to 7%), and the seroprevalence of IgA types 2 and 3 was low in older vaccinated children (2 to 3%). The seroprevalence of antibodies to type 1 was significantly higher (18%) in older children than in younger children. This higher seroprevalence is most likely explained by the persistence of IgA following infection with the serotype 1 wild-type poliovirus strain during the 1978 epidemic. In healthy adults, the seroprevalence of type 1- and type 2-specific IgA was significantly higher than that in young children. These results suggest that at least part of the IgA found in the older population is induced by infections unrelated to the IPV vaccination schedule. Finally, we found that parenteral vaccination with IPV was able to boost secretory IgA responses in 74 to 87% of a naturally exposed elderly population (n = 54). While the presence of secretory IgA in IPV-vaccinated persons has been documented previously, our findings suggest that mucosal priming with live virus is necessary to obtain an IgA response after IPV booster vaccination.

Adolescent↗
PubMed1997

Evaluation of a poliovirus-binding inhibition assay as an alternative to the virus neutralization test.

An enzyme-linked immunosorbent assay (ELISA)-based poliovirus-binding inhibition (PoBI) test to detect and quantify antibodies to polioviruses was optimized and evaluated for use in population studies as an alternative to the virus neutralization test (NT) in tissue culture. The sensitivities of the inhibition ELISA compared with the NT in an inactivated poliovirus vaccine (IPV)-vaccinated population were 98.6, 97.4, and 92.1% for serotypes 1, 2, and 3, respectively. The specificities of the PoBI test, as determined with sera from nonvaccinated persons, were also high for all three serotypes (99.0, 95.8, and 100%, respectively). Antibodies to other enteroviruses did not cross-react in the serotype 1 and 3 PoBI, and only levels of cross-reactivity were found for serotype 2. We found high correlations between the PoBI and NT titers for serotypes 1 and 2 in IPV-vaccinated blood donors (0.97 and 0.95), in oral poliovirus vaccine (OPV)-vaccinated blood donors (0.91 and 0.95), and in naturally immune persons (0.90 and 0.87). The correlation coefficient for serotype 3, however, was significantly lower in OPV-vaccinated blood donors (0.73) and in naturally immune persons (0.76) than in IPV-vaccinated persons (0.94; P < 0.01). These results indicate that the antibody response to serotype 3 poliovirus in IPV recipients is different from that in OPV recipients and naturally infected persons. We conclude that the PoBI test is a suitable alternative to the NT for estimating the seroprevalence of neutralizing antibodies to poliovirus, especially in large-scale population studies.

Animals↗
PubMed1996

Molecular detection and epidemiology of small round-structured viruses in outbreaks of gastroenteritis in the Netherlands.

To study the epidemiology of small round-structured viruses (SRSV) in the Netherlands, all outbreaks of gastroenteritis that were reported to the Research Laboratory for Infectious Diseases, Department of Virology, National Institute of Public Health and the Environment (RIVM) in 1994 and 1995 were examined using electron microscopy (EM), single-round reverse transcription-polymerase chain reaction (RT-PCR), and sequencing. To enable this, a generic SRSV-specific primer pair was developed that could detect 85% of a panel of antigenically diverse SRSV. By EM, SRSV could be detected in 86% and by RT-PCR in 91% of the reported gastroenteritis outbreaks. Partial sequence analysis of the polymerase region of these viruses revealed that two different clusters of viruses were responsible for the majority of the outbreaks. This strongly suggests epidemic spread of SRSV in the Netherlands.

Base Sequence↗
PubMed1995

Evidence for gammacerane as an indicator of water column stratification.

A new route for the formation of gammacerane from tetrahymanol is proposed; in addition to dehydration and hydrogenation, sulphurisation and early C-S cleavage are shown to be important in the pathway of formation, especially in marine sediments. Evidence is twofold. First, relatively large amounts of the gammacerane skeleton are sequestered in S-rich macromolecular aggregates formed by natural sulphurisation of functionalised lipids. Selective cleavage of polysulphide linkages with MeLi/MeI led to formation of 3-methylthiogammacerane, indicating that the gammacerane skeleton is primarily bound via sulphur at position 3, consistent with the idea that tetrahymanol (or the corresponding ketone) is the precursor for gammacerane. Second, upon mild artificial maturation of two sediments using hydrous pyrolysis, gammacerane is released from S-rich macromolecular aggregates by cleavage of the relatively weak C-S bonds. The stable carbon isotopic compositions of gammacerane and lipids derived from primary producers and green sulphur bacteria in both the Miocene Gessoso-solfifera and Upper Jurassic Allgau Formations indicate that gammacerane is derived from bacterivorous ciliates which were partially feeding on green sulphur bacteria. This demonstrates that anaerobic ciliates living at or below the chemocline are important sources for gammacerane, consistent with the fact that ciliates only biosynthesize tetrahymanol if their diet is deprived of sterols. This leads to the conclusion that gammacerane is an indicator for water column stratification, which solves two current enigmas in gammacerane geochemistry. Firstly, it explains why gammacerane is often found in sediments deposited under hypersaline conditions but is not necessarily restricted to this type of deposits. Secondly, it explains why lacustrine deposits may contain abundant gammacerane since most lakes in the temperate climatic zones are stratified during summer.

Animals↗
PubMed1995

Molecular epidemiology of wild poliovirus type 1 in Europe, the Middle East, and the Indian subcontinent.

The genomic relationships of wild poliovirus type 1 strains recently isolated in Europe, the Middle East, and the Indian subcontinent was analyzed by automated amplicon sequencing of the VP1/2A junction region of the genome. Four major genotypes of poliovirus type 1 were found to circulate. Two genotypes were found predominantly in Eastern Europe, one of these in the Caucasian Region and the other in countries bordering the Black Sea. A third genotype circulated mainly in Egypt. The fourth and largest genotype circulated in the largest geographic area. Strains belonging to this genotype could be found in countries as far apart as Malaysia and Ukraine. Considerable genetic variation was observed among strains isolated in Egypt, Pakistan, and India, where poliovirus is endemic. Strains belonging to all four genotypes circulated in Pakistan. Data confirm the extent of poliovirus circulation in certain regions, stressing the need for intensification of vaccination in these regions.

Base Sequence↗
PubMed1995

Molecular characterization of a wild poliovirus type 3 epidemic in The Netherlands (1992 and 1993).

An outbreak of poliomyelitis due to wild poliovirus type 3 (PV3) occurred in an unvaccinated community in The Netherlands between September 1992 and February 1993. The outbreak involved 71 patients. The aim of this study was to characterize the virus at the molecular level and to analyze the molecular evolution of the epidemic virus. Molecular analysis was carried out by sequencing the VP1/2A junction region (150 nucleotides) of 50 PV3 strains isolated in association with this outbreak and the entire VP1 gene of 14 strains. In addition, the sequence of the VP1/2A junction region of strains from geographical regions endemic for PV3 (Egypt, India, and Central Asia) was analyzed and compared with the nucleotide sequence of the epidemic strain from The Netherlands. The earliest isolate was obtained from river water sampled 3 weeks before diagnosis of the first poliomyelitis patient and was found by VP1/2A sequence analysis to be genetically identical to the strain isolated from the first patient. Sequence divergence among the strains from the epidemic in The Netherlands was less than 2%. The closest genetic similarity (97.3%) was found with an Indian isolate (New Delhi, December 1991), indicating the likely source of the virus. A more than 99% sequence similarity was found in the VP1/2A region. Finally, the sequence information was used to design primers for the specific and highly sensitive molecular detection of PV3 strains during the epidemic.

Base Sequence↗
PubMedDate not supplied

Norwalk-like calicivirus genes in farm animals.

Viruses closely related to Norwalk-like viruses (NLVs) were recently found in stored stool samples from two calves (United Kingdom and Germany) and four pigs (Japan), sparking discussions about the potential for zoonotic transmission. To investigate if NLVs are commonly present in farm animals, pooled stool samples from 100 pig farms, 48 chicken farms, 43 dairy cow herds, and 75 veal calf farms from the Netherlands were assayed by reverse transcription- polymerase chain reaction amplification, using primers specific for the detection of NLVs from humans. NLV RNA was detected in 33 (44%) of the specimens from veal calf farms and two (2%) specimens from pig farms. Our data show that NLV infections until recently thought to be restricted to humans occur often in calves and sometimes in pigs. While zoonotic transmission has not been proven, these findings suggest that calves and pigs may be reservoir hosts of NLVs.

Animals↗
PubMedDate not supplied

Gastroenteritis in sentinel general practices,The Netherlands.

From 1996 to 1999, the incidence of gastroenteritis in general practices and the role of a broad range of pathogens in the Netherlands were studied. All patients with gastroenteritis who had visited a general practitioner were reported. All patients who had visited a general practitioner for gastroenteritis (cases) and an equal number of patients visiting for nongastrointestinal symptoms (controls) were invited to participate in a case-control study. The incidence of gastroenteritis was 79.7 per 10,000 person years. Campylobacter was detected most frequently (10% of cases), followed by Giardia lamblia (5%), rotavirus (5%), Norwalk-like viruses (5%) and Salmonella (4%). Our study found that in the Netherlands (population 15.6 million), an estimated 128,000 persons each year consult their general practitioner for gastroenteritis, slightly less than in a comparable study in 1992 to 1993. A pathogen could be detected in almost 40% of patients (bacteria 16%, viruses 15%, parasites 8%).

Adolescent↗