Continued seasonal circulation of enterovirus D68 in the Netherlands, 2011-2014.

Enterovirus D68 (EV-D68) continued to circulate in a seasonal pattern in the Netherlands, after the outbreak in 2010. Outpatient EV-D68 cases, mainly in the under 20 and 50­59 years age groups, presented with relatively mild respiratory disease. Hospital-based enterovirus surveillance identified more severe cases, mainly in children under 10 years of age. Dutch partial VP1 genomic region sequences from 2012 through 2014 were distributed over three sublineages similar to EV-D68 from the outbreak in the US in 2014.

Immunity against poliomyelitis in the Netherlands, assessed in 2006 to 2007: the importance of completing a vaccination series.

Europe has been declared polio-free since 2002. Here we describe the seroprotection against poliomyelitis in the Dutch population using banked serum samples. Samples from 1,581 inhabitants of eight municipalities with low vaccination coverage (LVC) and an additional 6,386 samples from a nationwide (NS) group (clinical trial number: ISRCTN20164309; collected in 2006­07) were tested for neutralising antibodies (log² reciprocal titres (GMT); non-protection <3) against all three poliomyelitis serotypes. Demographic and epidemiological data were used for statistical regression analysis. Seroprevalence in the NS was 94.6% (type 1), 91.8% (type 2) and 84.0% (type 3). Infants (0­7 months-old) had ≥80% seroprevalence for all serotypes. The highest seroprevalence was found in children, with type 1 and type 2 in five year-olds and type 3 in nine to 10 year-olds. In the LVC group, orthodox protestants, many of whom refuse vaccination, showed seroprevalence rates of 64.9% (type 1), 61.0% (type 2) and 62.1% (type 3). In the NS group, non-Western immigrants and travellers to non-European continents had higher seroprevalences compared to Western immigrants and travellers within Europe, respectively. The Dutch National Immunisation Programme against poliomyelitis has provided good seroprotection, with high and long-lasting GMTs against all serotypes upon completion. The unvaccinated population remains at risk.

Detection of human enteroviruses and parechoviruses as part of the national enterovirus surveillance in the Netherlands, 1996-2011.

Laboratories of the Dutch Working Group on Clinical Virology have routinely performed enterovirus diagnostics in the Netherlands since the early 1960s, with country-wide coverage. Enterovirus-positive samples are typed for clinical and epidemiological purposes, as well as to document the absence of poliovirus circulation. Human parechoviruses 1 and 2, initially recognized as enteroviruses, and since 2006 also the higher numbered human parechovirus types, have been detected as part of this surveillance. The purpose of this report is to describe the national enterovirus surveillance data from stool specimens collected in the Netherlands between 1996 and 2011 by all the participating laboratories. Since 2007, the average annual percentage of human enterovirus- and parechovirus-positive specimens increased from 6.5 to 10.8% and from 0.3 to 2.5% of the total numbers of specimens tested, respectively, following a gradual implementation of molecular diagnostics directly on clinical samples. Increased detection rates were observed for human enterovirus species A coxsackieviruses (from 0.1 to 0.5%). Human enteroviruses of species B, C, and D were detected at average rates of 4.7, 0.04, and 0.005%, respectively. The introduction of molecular diagnostics also resulted in an increase in the number of untyped enterovirus-positive specimens for which the presence of poliovirus was not excluded (from 1.3 to 3.1% since 2007). To increase knowledge on human entero- and parechovirus epidemiology and type-specific pathogenesis, as well as to warrant the quality of the poliovirus surveillance in the Netherlands, it is of importance to continue the typing of enterovirus- and parechovirus-positive samples.

Laboratory-based surveillance in the molecular era: the TYPENED model, a joint data-sharing platform for clinical and public health laboratories.

Laboratory-based surveillance, one of the pillars of monitoring infectious disease trends, relies on data produced in clinical and/or public health laboratories. Currently, diagnostic laboratories worldwide submit strains or samples to a relatively small number of reference laboratories for characterisation and typing. However, with the introduction of molecular diagnostic methods and sequencing in most of the larger diagnostic and university hospital centres in high-income countries, the distinction between diagnostic and reference/public health laboratory functions has become less clear-cut. Given these developments, new ways of networking and data sharing are needed. Assuming that clinical and public health laboratories may be able to use the same data for their own purposes when sequence-based testing and typing are used, we explored ways to develop a collaborative approach and a jointly owned database (TYPENED) in the Netherlands. The rationale was that sequence data - whether produced to support clinical care or for surveillance -can be aggregated to meet both needs. Here we describe the development of the TYPENED approach and supporting infrastructure, and the implementation of a pilot laboratory network sharing enterovirus sequences and metadata.

Role of environmental poliovirus surveillance in global polio eradication and beyond.

Environmental poliovirus surveillance (ENV) means monitoring of poliovirus (PV) transmission in human populations by examining environmental specimens supposedly contaminated by human faeces. The rationale is based on the fact that PV-infected individuals, whether presenting with disease symptoms or not, shed large amounts of PV in the faeces for several weeks. As the morbidity:infection ratio of PV infection is very low, this fact contributes to the sensitivity of ENV which under optimal conditions can be better than that of the standard acute flaccid paralysis (AFP) surveillance. The World Health Organization has included ENV in the new Strategic Plan of the Global Polio Eradication Initiative for years 2010-2012 to be increasingly used in PV surveillance, supplementing AFP surveillance. In this paper we review the feasibility of using ENV to monitor wild PV and vaccine-derived PV circulation in human populations, based on global experiences in defined epidemiological situations.

[Poliomyelitis in 2006: all or nothing]. / Poliomyelitis in 2006: alles of niets.

Since it was launched in 1988, the Global Polio Eradication Initiative has made great progress: millions of children have been saved from a serious disease and type 2 poliovirus has been eradicated. The original target of polio eradication by the year 2000 was, however, too optimistic: as of 2006, polio remains endemic in 4 countries (Nigeria, India, Pakistan and Afghanistan). In northern Nigeria, it is particularly difficult to reach enough children during National Immunisation Days to stop the circulation of wild poliovirus and prevent spread to neighbouring countries that are at risk for epidemics due to low routine vaccination coverage. However, critics of the initiative provide no real alternative. The WHO will continue the initiative using new strategies to realise--for the second time in history after smallpox--the eradication ofa serious infectious disease.

Genes and regulatory sequences of bacteriophage phi X174.

Fragments of the DNA of bacteriophage phi X174 were inserted in the plasmids pACYC177 and pBR322, in order to test the in vivo effects of separate phage genes and regulatory sequences. The phi X174 inserts were identified by recombination and complementation with phage mutants, followed by restriction enzyme analysis. The genes B, C, F and G can be maintained stably in the cell even when there is efficient expression of these viral genes. Recombinant plasmids with the complete genes D and E can only be maintained when the expression of these genes is completely blocked. Expression of complete H and J genes could not yet be demonstrated. The intact gene A was apparently lethal for the host cell, as it was never found in the recombinants. The genes F and G are expressed, even when they are not preceded by one of the well characterized viral or plasmid promoter sequences. Screening of the nucleotide sequence of phi X174 gives two promoter-like sequences just in front of the two genes. Viral sequences with replication signals (the phi X174 (+) origin of replication, the initiation site for complementary strand synthesis and the incompatibility sequence) appeared to be functional also when inserted in recombinant plasmids. A plasmid with the phi X (+) origin can be forced to a rolling circle mode of replication. The A protein produced by infecting phages works in trans on the cloned viral origin. The (-) origin can function as initiation signal for complementary strand synthesis during transduction of single-stranded plasmid DNA. The intracellular presence of the incompatibility sequence on a plasmid prevents propagation of infecting phages.

Characterization of fastidious adenovirus types 40 and 41 by DNA restriction enzyme analysis and by neutralizing monoclonal antibodies.

The DNA of 48 strains of adenovirus type 40 (Ad40) and of 128 strains of adenovirus type 41 (Ad41), isolated between 1971 and 1986 from various countries, was characterized by restriction enzyme analysis using nine and ten restriction endonucleases respectively. Five new DNA variants of Ad40 and 18 new DNA variants of Ad41 were detected. Most of the restriction sites which differed among the various DNA variants appeared to be distributed at random over the entire length of the viral genomes of the two serotypes. The number of restriction sites by which two DNA variants differed from each other was used as a measure of their relatedness. Several clusters of closely related DNA variants were observed for each of the two serotypes. The 35 DNA variants of Ad40 and Ad41 were used to test monoclonal antibody preparations for their range of reactivity in a neutralization assay. One monoclonal antibody (5-8), raised against Ad40 strain Dugan, showed type-specific neutralization of all 11 Ad40 DNA variants tested. Six monoclonal antibodies, raised against Ad41 strain Tak, neutralized different proportions of the variants of Ad41. Two of these preparations (1-21 and 3-19) neutralized all 24 Ad41 DNA variants, while a third (1-23) reacted with only 12 Ad41 variants. Three other monoclonal antibody preparations (3-10, 3-18, 7-14) reacted specifically with only 6 of these 12 variants. The patterns of reactivity with the monoclonal antibody preparations correlated with the presence or absence of a HindIII restriction site at 56 map units and of an EcoRI restriction site at 52 map units on the Ad41 DNA. This region of the adenovirus DNA codes for the hexon protein, which is known to contain the type-specific neutralizing antigenic determinants.

Molecular epidemiology of poliovirus infection in Tunisia.

This report is an overview of poliomyelitis surveillance in Tunisia from 1991 to 1996. In all, 2088 stool specimens, collected from 152 acute flaccid paralysis (AFP) cases and from 1747 of their healthy contacts were investigated. Virus isolation was done systematically in RD and HEp-2C cell lines and isolated viruses were typed by sero-neutralisation as polioviruses or non-polio enteroviruses. Poliovirus isolates were analysed systematically for their wild or vaccine-related origin by two methods--one based on antigenic differences and one on genetic differences between strains. All type 2 polioviruses were vaccine-related and most wild viruses belonged to polio serotype 3. Wild polio type 3 viruses were detected in 1991 and 1992 in six cases of paralytic polio. A silent circulation of wild polio 1 and wild polio 3 was detected in 1994. No wild virus was detected in Tunisia from 1995 onwards. Wild polioviruses were sequenced and compared with Tunisian wild strains isolated during the 1980s, as well as other genotypes from the international database. These investigations revealed a single Tunisian polio 3 genotype that has been circulating from 1985 to 1994 and two different polio 1 genotypes. These results reflect effective control strategies within the country and contribute to the improvement of the polio eradication programme effectiveness at national and global levels.

Development and evaluation of monoclonal antibody-based immune electron microscopy for diagnosis of adenovirus types 40 and 41.

Immune electron microscopy based on monoclonal antibodies was developed and evaluated for diagnosis of adenovirus type 40 and adenovirus type 41 directly from clinical specimens. One adenovirus type 40 monoclonal (5-8) and one adenovirus type 41 monoclonal (5-15) were found to react to high titre with homotypic but not heterotypic antigen. These monoclonals were tested on a coded batch of 20 stools which contained adenovirus type 40 or adenovirus type 41. The results showed that 5/6 adenovirus type 40 and 13/14 adenovirus type 41 strains were correctly serotyped but one strain of each type failed to react with either serum. A wide variation in the numbers of virions bound to positive grids was observed. A further coded batch of 27 specimens, a mixture of subgenus F (i.e. type 40 or 41) or non-subgenus F adenoviruses, was then tested. There was complete serotype concordance with reference results for 16/19 subgenus F strains and all 8 non-subgenus F adenoviruses gave negative results. However, three subgenus F adenoviruses also gave negative results. In conclusion, monoclonal antibody-based immune electron microscopy accurately distinguished adenovirus type 40 from adenovirus type 41 and both viruses from other adenovirus serotypes in clinical specimens and will therefore be useful in the diagnosis of adenovirus gastroenteritis, but some strains may be missed, presumably because of antigenic variation in surface epitopes.

['Open season in the hunt for poliovirus' (continued)]. / 'De jacht op het poliovirus is geopend' (vervolg).

Global eradication of poliomyelitis was started in 1988. Polio eradication is considered feasible on theoretical and practical grounds, is cost-effective and is endorsed at the highest political levels. The strategy is based on (a) increasing vaccination coverage through routine immunization, national immunization days and so-called mopping-up campaigns, (b) improving surveillance, and (c) polio-free certification. Since the start of the programme global vaccination coverage increased from 67% in 1988 to 83% in 1995; the number of reported cases--an estimated 10% of the total number--decreased by 90% from 35,251 (1988) to 3,755 (1996). A rapid further decrease is expected with the start of national immunization days on the Indian subcontinent. In the next years the emphasis will be strongly on surveillance i.e. detection of possible polio patients and (wild) poliovirus circulation. All countries will need to implement reliable surveillance to show their polio-free status. Only then can the world be declared polio-free.

[Virological and serological aspects of the Dutch polio epidemic in 1992]. / Virologische en serologische aspecten van de Nederlandse polio-epidemie in 1992.

During the 1992 poliovirus type 3 outbreak in the Netherlands virological and serological investigations were conducted. No molecular epidemiological link was traced between poliovirus type 3 that caused the outbreak of poliomyelitis in the Netherlands and isolates from previous epidemics investigated. Serological neutralization assessments indicate that the inactivated poliomyelitis vaccine used in the Dutch national immunization schedule induces immunity to the causative agent.

[Progressive multifocal leukoencephalopathy in a female patient with chronic lymphatic leukemia]. / Progressieve multifocale leuko-encefalopathie bij een patiënte met chronische lymfatische leukemie.

This case report describes a 78-year old female patient with chronic lymphocytic leukaemia and neurological symptoms due to progressive multifocal leukoencephalopathy (PML). At autopsy the histopathology was characteristic, the involvement of JC virus was established. PML occurs in immunocompromised patients and is caused by infection with JC papova virus. Epidemiology, clinical course, diagnostic procedures with special reference to the use of the polymerase chain reaction, and therapy are briefly reviewed.

[An adenovirus epidemic in patients with kidney transplantation]. / Een adenovirusepidemie onder niertransplantatiepatiënten.

During weekly routine virological screening of kidney transplant patients 12 out of 15 patients within a period of four months were found to be infected with adenovirus. All isolates were of the same serotype, type AdII + 35/HII. However, DNA restriction enzyme analyses showed the presence of two different DNA variants which were associated with three different epidemiological episodes. The epidemic probably started with reactivation of latent virus in a limited number of patients, after which it spread nosocomially. None of the patients showed signs or symptoms clearly attributable to adenoviruses, although adenovirus could not be excluded as a cofactor in the fatal outcome of hepatitis in one of the patients. Adenovirus apparently can easily spread nosocomially. Since literature data suggest that adenovirus infections of transplant patients may result in serious complications, adenovirus should not be neglected in virological screening protocols for kidney transplant patients.

Genome type analysis of adenovirus 37 isolates.

Seventy-six strains of adenovirus type 37 (AV37), isolated during a period of 10 years from 73 patients on three continents, were analysed with eight DNA restriction endonucleases. Strains identical with the prototype (56 strains) prevailed; four deviating genome types were found, which differed only slightly from the prototype, with one exception. Half of the strains were tested in detail by neutralisation and haemagglutination inhibition. Minor differences in neutralisation were not reflected by differences in DNA restriction patterns. In comparison to genome types of other subgenera, field strains of adenovirus 37 showed only a moderate genetic variability.

An epidemic of keratoconjunctivitis due to adenovirus type 37.

An epidemic of keratoconjunctivitis due to adenovirus type 37 in Liverpool in 1984 is reported. Initially serum neutralisation suggested that isolates were type 10 but further neutralisation studies supported by DNA restriction enzyme analysis showed that they were type 37. Clinical and epidemiological features of this cause of epidemic keratoconjunctivitis, recently recognised in the United Kingdom, are presented and the implications for the laboratory investigation discussed.

Initiation signals for complementary strand DNA synthesis on single-stranded plasmid DNA.

The bacteriophage 0X174 origin for (+) strand DNA synthesis, when inserted in a plasmid, is in vivo a substrate for the initiator A protein, that is produced by infecting phages. The result of this interaction is the packaging of single-stranded plasmid DNA into preformed phage coats. These plasmid particles can transduce 0X-sensitive cells; however, the transduction efficiency depends strongly on the presence in the packaged DNA strand of an initiation signal for complementary strand DNA synthesis. A plasmid with the complementary (-) strand origin of 0X inserted in the same strand as the viral (+) origin transduces 50-100 times more efficient than the same plasmid without the (-) origin of 0X. The transduction efficiency of such a particle is comparable to the infection efficiency of the phage particle. It is shown that in this system the 0X (-) origin can be replaced by the complementary strand origins of the bacteriophages G4 and M13. We have used this system to isolate sequences, from E. coli plasmids (pACYC177, CloDF13, miniF and OriC) and from the E. coli chromosome that can function as initiation signals for the conversion of single-stranded plasmid DNA to double-stranded DNA. All isolated origins were found to be dependent for their activity on the dnaB, dnaC and dnaG proteins. We conclude that these signals were all primosome-dependent origins and that primosome priming is the major mechanism for initiation of the lagging strand DNA synthesis in E. coli. The assembly of the primosome depends on the sequence-specific interaction of the n' protein with single-stranded DNA. We have used the isolated sequences to deduce a consensus recognition sequence for the n' protein. The role of a possible secondary structure in this sequence is discussed.