Piet Maes

Prof. Dr. Piet Maes


Research Focus & Metrics

Academic Career Length

24Years (2003-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 April 2008 in Journal of Virology
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Journal Article
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JMJelle Matthijnssens
Jelle Matthijnssens
MCMax Ciarlet
Max Ciarlet
EHErica Heiman
Erica Heiman
IAIngrid Arijs
Ingrid Arijs
TDThomas Delbeke
Thomas Delbeke
MRMarc Van Ranst
Marc Van Ranst
Group A rotavirus classification is currently based on the molecular properties of the two outer layer proteins, VP7 and VP4, and the middle layer protein, VP6. As reassortment of all the 11 rotavirus gene segments plays a key role in generating rotavirus diversity in nature, a classification system that is based on all the rotavirus gene segments is desirable for determining which genes influence rotavirus host range restriction, replication, and virulence, as well as for studying rotavirus epidemiology and evolution. Toward establishing such a classification system, gene sequences encoding VP1 to VP3, VP6, and NSP1 to NSP5 were determined for human and animal rotavirus strains belonging to different G and P genotypes in addition to those available in databases, and they were used to define phylogenetic relationships among all rotavirus genes. Based on these phylogenetic analyses, appropriate identity cutoff values were determined for each gene. For the VP4 gene, a nucleotide identity cutoff value of 80% completely correlated with the 27 established P genotypes. For the VP7 gene, a nucleotide identity cutoff value of 80% largely coincided with the established G genotypes but identified four additional distinct genotypes comprised of murine or avian rotavirus strains. Phylogenetic analyses of the VP1 to VP3, VP6, and NSP1 to NSP5 genes showed the existence of 4, 5, 6, 11, 14, 5, 7, 11, and 6 genotypes, respectively, based on nucleotide identity cutoff values of 83%, 84%, 81%, 85%, 79%, 85%, 85%, 85%, and 91%, respectively. In accordance with these data, a revised nomenclature of rotavirus strains is proposed. The novel classification system allows the identification of (i) distinct genotypes, which probably followed separate evolutionary paths; (ii) interspecies transmissions and a plethora of reassortment events; and (iii) certain gene constellations that revealed (a) a common origin between human Wa-like rotavirus strains and porcine rotavirus strains and (b) a common origin between human DS-1-like rotavirus strains and bovine rotaviruses. These close evolutionary links between human and animal rotaviruses emphasize the need for close simultaneous monitoring of rotaviruses in animals and humans.

1 October 2004 in Biochemical and Biophysical Research Communications
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EKEls Keyaerts
Els Keyaerts
LVLeen Vijgen
Leen Vijgen
PMPiet Maes
Piet Maes
JNJohan Hendrik Neyts
Johan Hendrik Neyts
MRMarc Van Ranst
Marc Van Ranst

1 January 2009 in BMC Microbiology
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Journal Article
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PMPiet Maes
Piet Maes
JMJelle Matthijnssens
Jelle Matthijnssens
MRMustafizur Rahman
Mustafizur Rahman
MRMarc Van Ranst
Marc Van Ranst
Group A rotaviruses are the most common cause of severe diarrhea in infants and children worldwide and continue to have a major global impact on childhood morbidity and mortality. In recent years, considerable research efforts have been devoted to the development of two new live, orally administered vaccines. Although both vaccines have proven to confer a good protection against severe rotavirus gastroenteritis, these vaccines will have to be screened and may have to be updated regularly to reflect temporal and spatial genotype fluctuations. In this matter, the genetic characterization of circulating and new emerging rotavirus strains will need to be compulsory and accurate. An extended classification system for rotaviruses in which all the 11 genomic RNA segments are used, has been proposed recently. The use of this classification system will help to elucidate the role of gene reassortments in the generation of genetic diversity, host range restriction, co-segregation of certain gene segments, and in adaptation to a new host species.

5 October 2016 in Nucleic Acids Research
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KDKoenraad Van Doorslaer
Koenraad Van Doorslaer
ZLZhiwen Li
Zhiwen Li
SXSandhya Xirasagar
Sandhya Xirasagar
PMPiet Maes
Piet Maes
DKDavid Kaminsky
David Kaminsky
AMAlison Mcbride
Alison Mcbride
The Papillomavirus Episteme (PaVE) is a database of curated papillomavirus genomic sequences, accompanied by web-based sequence analysis tools. This update describes the addition of major new features. The papillomavirus genomes within PaVE have been further annotated, and now includes the major spliced mRNA transcripts. Viral genes and transcripts can be visualized on both linear and circular genome browsers. Evolutionary relationships among PaVE reference protein sequences can be analysed using multiple sequence alignments and phylogenetic trees. To assist in viral discovery, PaVE offers a typing tool; a simplified algorithm to determine whether a newly sequenced virus is novel. PaVE also now contains an image library containing gross clinical and histopathological images of papillomavirus infected lesions. Database URL: https://pave.niaid.nih.gov/.

1 March 2016 in PLOS Medicine
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DSDaouda Sissoko
Daouda Sissoko
CLCédric LAOUENAN
Cédric LAOUENAN
EFElin Folkesson
Elin Folkesson
AMAbdoul-Bing M’lebing
Abdoul-Bing M’lebing
ABAbdoul-Habib Beavogui
Abdoul-Habib Beavogui
JGJIKI Study Group
JIKI Study Group
Ebola virus disease (EVD) is a highly lethal condition for which no specific treatment has proven efficacy. In September 2014, while the Ebola outbreak was at its peak, the World Health Organization released a short list of drugs suitable for EVD research. Favipiravir, an antiviral developed for the treatment of severe influenza, was one of these. In late 2014, the conditions for starting a randomized Ebola trial were not fulfilled for two reasons. One was the perception that, given the high number of patients presenting simultaneously and the very high mortality rate of the disease, it was ethically unacceptable to allocate patients from within the same family or village to receive or not receive an experimental drug, using a randomization process impossible to understand by very sick patients. The other was that, in the context of rumors and distrust of Ebola treatment centers, using a randomized design at the outset might lead even more patients to refuse to seek care. Therefore, we chose to conduct a multicenter non-randomized trial, in which all patients would receive favipiravir along with standardized care. The objectives of the trial were to test the feasibility and acceptability of an emergency trial in the context of a large Ebola outbreak, and to collect data on the safety and effectiveness of favipiravir in reducing mortality and viral load in patients with EVD. The trial was not aimed at directly informing future guidelines on Ebola treatment but at quickly gathering standardized preliminary data to optimize the design of future studies. Inclusion criteria were positive Ebola virus reverse transcription PCR (RT-PCR) test, age ≥ 1 y, weight ≥ 10 kg, ability to take oral drugs, and informed consent. All participants received oral favipiravir (day 0: 6,000 mg; day 1 to day 9: 2,400 mg/d). Semi-quantitative Ebola virus RT-PCR (results expressed in “cycle threshold” [Ct]) and biochemistry tests were performed at day 0, day 2, day 4, end of symptoms, day 14, and day 30. Frozen samples were shipped to a reference biosafety level 4 laboratory for RNA viral load measurement using a quantitative reference technique (genome copies/milliliter). Outcomes were mortality, viral load evolution, and adverse events. The analysis was stratified by age and Ct value. A “target value” of mortality was defined a priori for each stratum, to guide the interpretation of interim and final analysis. Between 17 December 2014 and 8 April 2015, 126 patients were included, of whom 111 were analyzed (adults and adolescents, ≥13 y, n = 99; young children, ≤6 y, n = 12). Here we present the results obtained in the 99 adults and adolescents. Of these, 55 had a baseline Ct value ≥ 20 (Group A Ct ≥ 20), and 44 had a baseline Ct value < 20 (Group A Ct < 20). Ct values and RNA viral loads were well correlated, with Ct = 20 corresponding to RNA viral load = 7.7 log10 genome copies/ml. Mortality was 20% (95% CI 11.6%–32.4%) in Group A Ct ≥ 20 and 91% (95% CI 78.8%–91.1%) in Group A Ct < 20. Both mortality 95% CIs included the predefined target value (30% and 85%, respectively). Baseline serum creatinine was ≥110 μmol/l in 48% of patients in Group A Ct ≥ 20 (≥300 μmol/l in 14%) and in 90% of patients in Group A Ct < 20 (≥300 μmol/l in 44%). In Group A Ct ≥ 20, 17% of patients with baseline creatinine ≥110 μmol/l died, versus 97% in Group A Ct < 20. In patients who survived, the mean decrease in viral load was 0.33 log10 copies/ml per day of follow-up. RNA viral load values and mortality were not significantly different between adults starting favipiravir within <72 h of symptoms compared to others. Favipiravir was well tolerated. In the context of an outbreak at its peak, with crowded care centers, randomizing patients to receive either standard care or standard care plus an experimental drug was not felt to be appropriate. We did a non-randomized trial. This trial reaches nuanced conclusions. On the one hand, we do not conclude on the efficacy of the drug, and our conclusions on tolerance, although encouraging, are not as firm as they could have been if we had used randomization. On the other hand, we learned about how to quickly set up and run an Ebola trial, in close relationship with the community and non-governmental organizations; we integrated research into care so that it improved care; and we generated knowledge on EVD that is useful to further research. Our data illustrate the frequency of renal dysfunction and the powerful prognostic value of low Ct values. They suggest that drug trials in EVD should systematically stratify analyses by baseline Ct value, as a surrogate of viral load. They also suggest that favipiravir monotherapy merits further study in patients with medium to high viremia, but not in those with very high viremia. ClinicalTrials.gov NCT02329054 In 2014 and 2015, an Ebola virus outbreak larger than any known before occurred in West Africa. Ebola virus disease (EVD) is highly contagious, and many infected people die. Central to the emergency response to the recent outbreak were local Ebola treatment centers where patients were diagnosed, were isolated, and received supportive care. With thousands of patients dying and many health workers contracting the disease, fear was ubiquitous and distrust abundant. While conducting research in this environment was extremely challenging, the urgent need for treatments and the opportunity to conduct studies that could bring such treatments closer to reality was also recognized. In September 2014, WHO released a short list of existing drugs that were candidates for clinical trials among patients infected in the outbreak. Favipiravir, an antiviral drug developed in Japan for patients with severe influenza, was on the list. Because of the urgent need to find drugs that could reduce deaths caused by Ebola, the researchers decided to conduct a clinical trial using favipiravir in patients with EVD in Guinea. In view of the circumstances, they decided against a randomized controlled trial and instead designed a study where all participants would receive the same treatment. In randomized controlled trials only some participants receive the treatment in addition to standard care, while others serve as a control group and receive standard care only, or standard care plus a placebo. Such studies allow stronger conclusions to be drawn about whether a treatment is safe and whether it works or not. The researchers had two main reasons for this decision. First, patients from the same family or village often sought EVD treatment at the same time, and the researchers felt that it was ethically unacceptable to randomize such groups, with only some of them receiving the experimental drug. Second, the strict isolation procedures imposed to interrupt virus transmission had intensified fear in affected communities and fueled rumors of illicit drug experimentation and organ theft at the treatment centers. In this context, the researchers worried that a randomized study might increase distrust among the community and the reluctance of patients to seek care. Rather than seeking definitive answers about the safety and efficacy of favipiravir in patients with EVD, the objectives of the study as it was designed were to test the feasibility and acceptability of an emergency trial in the context of a large Ebola outbreak and to learn lessons from the experience. In addition, the researchers planned to collect data on the safety and effectiveness of favipiravir in reducing mortality and viral load in patients with EVD in the hope that their preliminary findings could improve the design of subsequent trials and the chance to provide conclusive answers. After 13 weeks of preparation, the trial took place from December 2014 to April 2015 at four separate Ebola treatment centers, three in rural areas and one in an urban setting. In addition to standard care (which included rehydration, antimalarial and antibacterial therapies, and medication to reduce fever, pain, and nausea), all participants were given favipiravir by mouth for ten days, at doses substantially higher than those recommended for patients with influenza. Outcomes measured were mortality, viral load changes over time (based on blood samples), and adverse events. EVD was confirmed with an assay that used patient blood and provided an estimate of the viral load, that is, of how much virus the blood contained. Because viral load was known to influence the course of EVD, the researchers analyzed the participants in two groups, namely, those with a viral load estimate above a certain threshold and those with viral load estimate below the threshold. They also used existing data from Guinean patients diagnosed with Ebola earlier in the outbreak who had received only standard care and calculated an expected mortality rate for patients above and below the viral load threshold. The researchers were able to enroll 126 participants in the trial. Of these, 111 were included in the final analysis. Of 99 adult and adolescent participants 13 years and older, 55 were in the lower viral load group and 44 in the higher viral load group. Mortality was 20% in the former and 91% in the latter. Neither mortality rate was significantly different from that of earlier patients who had received only standard care. The researchers also found that favipiravir was well tolerated. None of the patients stopped the course of treatment, vomiting following drug intake was rare, and no severe adverse events were attributed to the drug. The researchers did not see a difference in mortality between patients who reported onset of symptoms less than three days before the start of treatment and those whose symptoms had started more than three days the start of treatment. The report shows that it is possible to conduct an emergency trial during an outbreak in a low-resource setting. In fact, at the time of its acceptance, this paper reported on an Ebola treatment trial larger than any other yet published. The experience described should be useful for similar undertakings in the future. The following conditions contributed to the success of the trial: close collaboration between researchers, local health officials, and affected communities on one hand, and flexibility in design, conduct, and analysis based on close monitoring and interim assessments on the other. Besides using interim results to influence the conduct and analysis of their own trial, the researchers also shared these results with the scientific community in real time, and this feedback influenced other research during the outbreak. The trial could not answer definitively whether favipiravir treatment was safe or reduced mortality in patients with EVD. The results suggest that the drug is unlikely to be beneficial for patients with very high viral loads, at least when given by itself. They also suggest that favipiravir is safe in patients with lower viral loads, and that in such patients additional efficacy studies are warranted. Intermediate analysis of various measurements in trial participants showed that the estimate of viral load from the field EVD diagnosis test is a good proxy for the actual viral load (determined after the samples were shipped to and analyzed in a reference laboratory in France) and suitable as a surrogate marker. The results also confirm that viral load is a strong predictor of mortality. This list of resources contains links that can be accessed when viewing the PDF on a device or via the online version of the article at http://dx.doi.org/10.1371/journal.pmed.1001967.

7 May 2019 in Archives of Virology
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AAAbulikemu Abudurexiti
Abulikemu Abudurexiti
SAScott Adkins
Scott Adkins
DADaniela Alioto
Daniela Alioto
SASergey Alkhovsky
Sergey Alkhovsky
TATatjana Avsic-Zupanc
Tatjana Avsic-Zupanc
Jens H. KuhnJens H. Kuhn
Jens H. Kuhn