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Piet Maes

Publications and source records attributed to Piet Maes.

At least 19 recordsLinked to original sources
PubMed2026

Emergence of a Bundibugyo virus variant in the 2026 outbreak in the Democratic Republic of the Congo and Uganda.

In May 2026, an outbreak of Ebola disease caused by Bundibugyo virus (BDBV, species Orthoebolavirus bundibugyoense) was declared in the Democratic Republic of the Congo (DRC), with cases originating from DRC and locally transmitted cases reported in Uganda. Bundibugyo virus disease (BVD) outbreaks were previously recorded in 2007-2008 in Bundibugyo District, Uganda, and in 2012 in Isiro, DRC. Here, we generated 22 genomes from samples obtained from individuals with BVD in DRC and Uganda. These genomes form a well-supported phylogenetic cluster separate from BDBV variants associated with the 2007 and 2012 outbreaks, together with evidence for sustained human transmission. This is consistent with the emergence of a new zoonotic spillover event rather than resurgence from previously reported variants. Besides ongoing efforts in strengthening surveillance systems, community engagement, establishing Ebola treatment centers, and developing targeted medical countermeasures; our report advocates to specifically increase decentralized laboratory diagnostics capacity, with pan-Orthoebolavirus assays, including genomic sequencing capacity, for limiting further outbreak expansion, timely detection and control of future outbreaks.

Journal Article↗
PubMed2025

Generation of Biologically Contained Marburg Virus.

Wild-type Marburg virus (MARV) can only be handled in biosafety level 4 facilities. By removing an essential gene from the virus genome, deficient virus particles can be generated that are only capable of replication if the missing gene product is provided in trans. As a result, these viruses are restricted to specific cell lines, making them safe to handle at lower biosafety levels. Here, we provide a detailed overview of how to generate MARV in which the VP30 gene has been replaced by a green fluorescent reporter gene, as well as how to use lentiviral transduction to create stable cell lines expressing MARV VP30. These cell lines can be used for the propagation and confinement of the resulting reporter virus.

Marburgvirus↗
PubMed2006

Evaluation of the efficacy of disinfectants against Puumala hantavirus by real-time RT-PCR.

Puumala virus, a hantavirus belonging to the Bunyaviridae family, causes a human disease known as nephropathia epidemica, a mild form of hemorrhagic fever with renal syndrome. The implementation of effective decontamination procedures is critical in hantavirus research to minimize the risk of personnel exposure. This study investigated the efficacy of Clidox((R)), Dettol((R)), ethanol, Halamid-d((R)), peracetic acid, sodium hypochloride and Virkon((R))S for inactivating Puumala virus. A real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was used to quantify Puumala virus before and after treatment with these products. Inactivation of Puumala virus was effective after 10min with all products except ethanol. Inactivation with absolute ethanol was effective only after 30min. Using the qRT-PCR method, this study has shown that the commercially available products Clidox((R)), Halamid-d((R)) and Virkon((R))S in particular represent a rapid and safe way to decontaminate surfaces with possible Puumala virus contamination. These products can be used in solutions of 1-2%, with contact times greater than 10min, for inactivating effectively Puumala virus.

Disinfectants↗
PubMed2006

Truncated recombinant Dobrava hantavirus nucleocapsid proteins induce strong, long-lasting immune responses in mice.

We describe the cloning and expression of Dobrava hantavirus (DOBV) nucleocapsid proteins and a truncated form consisting of the first 118 N-terminal amino acids, and the capacity of these E. coli ICONE 200-expressed recombinant proteins (rNp) to induce a protective immune response against DOBV in mice. As an alternative carrier protein, the outer membrane protein A derived from Klebsiella pneumoniae (rP40) has been coupled to different rNp constructs. All recombinant proteins were found to be highly immunogenic after three immunizations of rNp. The immunizations resulted in the induction of a strong Np-specific IgG response with a predominance of IgG1 over IgG2b and IgG2a, suggesting a mixed Th1/Th2 cell involvement. A specific IgG3 response could not be detected. Mice immunized with recombinant DOBV rNp without rP40 showed lower nucleocapsid-specific antibody responses in comparison with the rP40-conjugated constructs, but all mice were found to be protected against DOBV challenge. Our results indicate that the rNp constructs coupled to rP40, represent promising vaccine candidates.

Adjuvants, Immunologic↗
PubMed2006

Tumor necrosis factor-alpha genetic predisposing factors can influence clinical severity in nephropathia epidemica.

Severe human infection with Hantavirus is characterized by high fever, cold chills, thrombocytopenia, arterial hypotension, acute renal failure, and/or adult respiratory distress syndrome (ARDS)-like pulmonary involvement, but the clinical course varies greatly between individuals. We investigated whether genetically determined differences in tumor necrosis factor (TNF)-alpha production can influence the severity of Hantavirus disease. We studied a TNF-alpha single-nucleotide promoter polymorphism (SNP) at position -238 (a guanine [G]-to-adenine [A] transition) and ex vivo TNF-alpha production in a recall study of 36 Belgian patients who had a serologically proven form of Puumala virus-induced Hantavirus infection with the kidney as main target organ. In our study, the highest creatinine levels were found in patients with the lowest ex vivo TNF-alpha production. Creatinine levels correlated inversely with TNF-alpha production (R = -0.35, p < 0.05). The number of thrombocytes was significantly lower in patients with the GA-238 genotype (low TNF-alpha producers) compared with patients with the GG-238 genotype. In our study, genetically determined low production of TNF-alpha was associated with some parameters indicating a more severe clinical course of Puumala Hantavirus infection in humans, possibly by impaired activation of TNF-alpha-dependent antiviral mechanisms, which could in turn result in decreased clearance of Hantavirus.

Genetic Predisposition to Disease↗
PubMed2006

Evolutionary history of the closely related group 2 coronaviruses: porcine hemagglutinating encephalomyelitis virus, bovine coronavirus, and human coronavirus OC43.

The close genetic and antigenic relatedness among the group 2 coronaviruses human coronavirus OC43 (HCoV-OC43), bovine coronavirus (BCoV), and porcine hemagglutinating encephalomyelitis virus (PHEV) suggests that these three viruses with different host specificities diverged fairly recently. In this study, we determined the complete genomic sequence of PHEV (strain PHEV-VW572), revealing the presence of a truncated group 2-specific ns2 gene in PHEV in comparison to other group 2 coronaviruses. Using a relaxed molecular clock approach, we reconstructed the evolutionary relationships between PHEV, BCoV, and HCoV-OC43 in real-time units, which indicated relatively recent common ancestors for these species-specific coronaviruses.

Animals↗
PubMed2006

Investigating the origin and spread of hepatitis C virus genotype 5a.

Epidemiological and phylogenetic studies of hepatitis C virus (HCV) have identified six major HCV genotypes and have attempted to characterize their origin and spread worldwide. Putative regions of endemic infection have been identified for all HCV genotypes except HCV genotype 5a. Although HCV genotype 5a was previously thought to be largely restricted to the northern part of South Africa, this study reports an unexpected cluster of the genotype in West Flanders Province in Belgium. To investigate the molecular epidemiology of this cluster and of HCV genotype 5a in general, a rigorous phylogenetic analysis of Belgian and South African HCV genotype 5a samples was performed. Remarkably, the Belgian and South African strains form two distinct clusters of similar diversity. We used a Bayesian coalescent method to estimate the rate of virus spread through time for HCV genotype 5a in both regions. Our results indicate that HCV genotype 5a strains have been spreading independently in Belgium and South Africa for more than 100 years, with a rate of spread characteristic of an epidemic genotype. These findings have major implications for tracing the origin of HCV genotype 5a. Here, we speculate about the possible origins of these clusters.

Belgium↗
PubMed2005

Viral load quantitation of SARS-coronavirus RNA using a one-step real-time RT-PCR.

INTRODUCTION: Severe acute respiratory syndrome (SARS) is an emerging infectious disease that first occurred in humans in the People's Republic of China in November 2002 and has subsequently spread worldwide. A novel virus belonging to the Coronaviridae family has been identified as the cause of this pulmonary disease. The severity of the disease combined with its rapid spread requires the development of fast and sensitive diagnostic assays. RESULTS: A real-time quantitative RT-PCR was designed in the nsp11 region of the replicase 1B domain of the SARS-coronavirus (SARS-CoV) genome. To evaluate this quantitative RT-PCR, cRNA standards were constructed by in vitro transcription of SARS-CoV Frankfurt 1 RNA using T7 RNA polymerase, followed by real-time RT-PCR. The assay allowed quantitation over a range of 10(2) to 10(8) RNA copies per reaction. CONCLUSIONS: Extrapolated to clinical samples, this novel assay has a detection range of 10(4) to 10(10) copies of viral genome equivalents per millilitre. In comparison to the current de facto cRNA Artus Biotech standard, the in-house cRNA standard gives a 100-fold higher absolute quantity, suggesting a possible underestimation of the viral load when using the Artus Biotech standard.

Animals↗
PubMed2005

Growth kinetics of SARS-coronavirus in Vero E6 cells.

Vero E6 cells are commonly used for in vitro studies of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) and for antiviral evaluation purposes. A better understanding of the SARS-CoV growth kinetics in Vero E6 cells is crucial to help elucidate the mechanism of antiviral activity of selective antiviral agents. In this study, the growth kinetics of SARS-CoV in Vero E6 cells were studied by quantitation of intra- and extracellular viral RNA load as well as extracellular virus yield at different time points post-infection. At 12h post-infection, the intracellular viral RNA load was 3x10(2)-fold higher than at the time of infection, and the extracellular viral RNA load was increased with a factor of 2 x 10(3). Intracellular viral RNA levels started to rise at 6h post-infection. One hour later (at 7h post-infection), the levels of extracellular SARS-CoV RNA also began to rise. This was corroborated by the fact that infectious progeny SARS-CoV also first appeared in the supernatant between 6 and 7h post-infection. At 12h post-infection, SARS-CoV reached titers in the supernatant of 5.2 x 10(3) CCID(50)/ml.

Animals↗
PubMed2005

Chromatography paper strip sampling of enteric adenoviruses type 40 and 41 positive stool specimens.

BACKGROUND: The enteric subgroup F adenoviruses type 40 (Ad40) and 41 (Ad41) are the second most important cause of acute infantile gastroenteritis after rotaviruses. Repeated community outbreaks have been associated with antigenic changes among the Ad40 and Ad41 strains due to host immune pressure. Therefore large field epidemiological surveys and studies on the genetic variations in different isolates of Ad40 and Ad41 are important for disease control programs, the design of efficient diagnostic kits and vaccines against subgroup F adenoviruses. A novel method using sodium dodecyl sulphate SDS/EDTA-pretreated chromatography paper strips was evaluated for the collection, storage and shipping of Ad40/41 contaminated stool samples. RESULTS: This study shows that adenoviral DNA can be successfully detected in the filter strips by PCR after four months storage at -20 degrees C, 4 degrees C, room temperature (20-25 degrees C) and 37 degrees C. Furthermore no adenoviral infectivity was observed upon contact with the SDS/EDTA-pretreated strips. CONCLUSIONS: Collecting, storing and transporting adenovirus type 40 and 41 positive stool samples on SDS/EDTA-pretreated chromatography filter strips is a convenient, biosafe and cost effective method for studying new genome variants and monitoring spread of enteric adenovirus strains during outbreaks.

Adenoviridae↗
PubMed2005

A novel pancoronavirus RT-PCR assay: frequent detection of human coronavirus NL63 in children hospitalized with respiratory tract infections in Belgium.

BACKGROUND: Four human coronaviruses are currently known to infect the respiratory tract: human coronaviruses OC43 (HCoV-OC43) and 229E (HCoV-229E), SARS associated coronavirus (SARS-CoV) and the recently identified human coronavirus NL63 (HCoV-NL63). In this study we explored the incidence of HCoV-NL63 infection in children diagnosed with respiratory tract infections in Belgium. METHODS: Samples from children hospitalized with respiratory diseases during the winter seasons of 2003 and 2004 were evaluated for the presence of HCoV-NL63 using a optimized pancoronavirus RT-PCR assay. RESULTS: Seven HCoV-NL63 positive samples were identified, six were collected during January/February 2003 and one at the end of February 2004. CONCLUSIONS: Our results support the notation that HCoV-NL63 can cause serious respiratory symptoms in children. Sequence analysis of the S gene showed that our isolates could be classified into two subtypes corresponding to the two prototype HCoV-NL63 sequences isolated in The Netherlands in 1988 and 2003, indicating that these two subtypes may currently be cocirculating.

Adolescent↗
PubMed2005

Frequency of the CCR5-Delta32 mutant allele is not increased in Belgian hepatitis C virus-infected patients.

A 32-base pair deletion in the CC-chemokine receptor 5 gene (CCR5), associated with resistance to human immunodeficiency virus type 1 (HIV-1) infection, has recently been suggested to act as an adverse host factor in hepatitis C virus (HCV) infection. To examine this hypothesis, we determined the CCR5-Delta32 allele frequency by polymerase chain reaction in a Belgian cohort of 163 HCV-infected patients and 310 healthy control subjects. The resulting CCR5-Delta32 allele frequencies were 0.080 and 0.119 for the patient group and control group, respectively. In contrast with a previous study, we could not show a statistically significant difference between the CCR5-Delta32 allele frequencies in HCV patients and controls. Moreover, genotype distributions in both populations were in agreement with Hardy-Weinberg equilibrium. Our results do not support the hypothesis that the CCR5-Delta32 mutant allele is a risk factor for hepatitis C virus infection.

Belgium↗
PubMed2005

Development of one-step, real-time, quantitative reverse transcriptase PCR assays for absolute quantitation of human coronaviruses OC43 and 229E.

The clinical significance of human coronaviruses in more severe respiratory illnesses has recently been shown to be higher than was previously assumed. Rapid and reliable diagnosis of human coronavirus infections therefore becomes indispensable in a routine clinical setting. In this study, we present a very sensitive and specific TaqMan-based, real-time quantitative reverse transcriptase PCR (qRT-PCR) for the rapid detection and quantitation of human coronaviruses (HCoVs) OC43 and 229E. Absolute viral load measurement in clinical samples was achieved through the construction of in-house HCoV OC43 and 229E cRNA standards for the generation of a standard curve. The HCoV OC43 assay allows quantitation over a range from 20 to 2 x 10(8) RNA copies per reaction mixture (5 microl RNA extract). When this is extrapolated to clinical samples, this corresponds to a detection range of 10(3) to 10(10) viral genome equivalents per ml. By using the HCoV 229E qRT-PCR assay, viral RNA copies ranging from 200 to 2 x 10(9) per reaction mixture can be detected, which corresponds to 10(4) to 10(11) viral genome equivalents per ml sample. A total of 100 respiratory samples screened for the presence of HCoVs OC43 and 229E by using conventional RT-PCR were assessed in parallel by the qRT-PCR assays. By use of the real-time qRT-PCR techniques, the detection rate of HCoVs OC43 and 229E increased from 2.0% to 3.1% and from 0.3% to 2.5%, respectively. The real-time qRT-PCR assays described here allow the rapid, specific, and sensitive laboratory detection and quantitation of human coronaviruses OC43 and 229E.

Child↗
PubMed2005

Use of a commercially available line probe assay for genotyping of hepatitis C virus 5a strains.

To validate a commercially available line probe assay for samples containing the infrequently found hepatitis C virus (HCV) genotype 5a, we sequenced a 511-nucleotide fragment of the NS4b region of Belgian and South African HCV genotype 5a samples. Phylogenetic analysis of the sequence data was performed. For the 77 HCV genotype 5a samples collected, there was 100% concordance between the genotype assignment by the line probe assay and the genotyping based on nucleotide sequencing, despite sequence heterogeneity in the probe binding sites of some samples.

5' Untranslated Regions↗
PubMed2004

Poliovirus sampling by using sodium dodecyl sulfate/EDTA-pretreated chromatography paper strips.

To achieve the goal of poliovirus eradication, surveillance of endemic areas is a crucial step in the poliovirus eradication program. Currently, six countries still have endemic poliovirus. We have tested a novel method which uses SDS/EDTA-treated chromatography paper strips to collect and transport poliovirus-containing stool samples. The SDS/EDTA-treated paper strips were soaked with different dilutions of poliovirus-containing feces and stored at different temperatures. After storing the SDS/EDTA paper strips for 5 months at 37 degrees C, poliovirus RNA could be successfully amplified using RT-PCR. Infectivity of wild-type poliovirus type 1, 2, and 3 was lost upon contact with the SDS/EDTA-treated strips. This easy, inexpensive, and biosafe chromatography paper strip method for the collection and transportation of poliovirus samples can be of use in poliovirus surveillance and polio vaccination programs.

Chromatography↗
PubMed2004

Evaluation of a norovirus sampling method using sodium dodecyl sulfate/EDTA-pretreated chromatography paper strips.

Noroviruses are the most common cause of nonbacterial gastroenteritis outbreaks. A novel method was tested that utilizes sodium dodecyl sulfate (SDS)/EDTA-pretreated chromatography paper strips to collect and transport norovirus-containing fresh stool samples. As confirmation, the strips were infected with different dilutions of human norovirus-containing faeces and stored at different temperatures (-80, -20, 4 degrees C, room temperature and 37 degrees C). Reverse transcription (RT)-PCR analysis was carried out after storage of the strips for 1, 7, 14, 60, and 120 days. The presence of amplifiable norovirus RNA on the strips was inversely correlated with the duration of storage and the storage temperature. Norovirus RNA remained detectable for a sufficient amount of time at room temperature or even in warmer climatic conditions to allow transportation of the samples from a field site to a reference laboratory using regular postal mail. To prove that viral infectivity was lost upon contact with the SDS/EDTA-treated strips, feline calicivirus F9 (10(7) TCID(50)/ml) was loaded onto the strips. After elution and dialysis, no cytopatic effect could be observed upon incubation on Crandell-Reese feline kidney cells. The SDS/EDTA-pretreated chromatography filter paper strips are an inexpensive, biosafe and adequate method to collect, transport and store norovirus samples.

Antiviral Agents↗