Andrej Steyer (Author), Tilen Konte (Author), Martin Sagadin (Author), Marko Kolenc (Author), Andrej Škoberne (Author), Julija Germ (Author), Tadeja Dovč (Author), Miha Arnol (Author), Mateja Poljšak-Prijatelj (Author)

Abstract

Noroviruses are the leading cause of acute gastroenteritis, and they can affect humans of all age groups. In immunocompromised patients, norovirus infections can develop into chronic diarrhea or show prolonged asymptomatic virus shedding. Chronic norovirus infections are frequently reported for solid organ transplant recipients, with rapid intrahost norovirus evolution seen. In this report, we describe a case of chronic norovirus infection in an immunocompromised patient who was followed up for over 5 years. The purpose of the study was to specify the norovirus evolution in a chronically infected immunocompromised host and identify possible selection sites in norovirus capsid protein. During the follow-up period, 25 sequential stool samples were collected and nine of them were selected to generate amplicons covering viral RNA-dependent RNA polymerase (RdRp) and viral capsid protein (VP1) genes. Amplicons were sequenced using next-generation sequencing. Single nucleotide polymorphisms were defined, which demonstrated a nearly 3-fold greater mutation rate in the VP1 genome region compared to the RdRp genome region (7.9 vs. 2.8 variable sites/100 nucleotides, respectively). This indicates that mutations in the virus genome were not accumulated randomly, but are rather the result of mutant selection during the infection cycle. Using ShoRAH software we were able to reconstruct haplotypes occurring in each of the nine selected samples. The deduced amino-acid haplotype sequences were aligned and the positions were analyzed for selective pressure using the Datamonkey program. Only 12 out of 25 positive selection sites were within the commonly described epitopes A, B, C, and D of the VP1 protein. New positive selection sites were determined that have not been described before and might reflect adaptation of the norovirus toward optimal histo-blood-group antigen binding, or modification of the norovirus antigenic properties. These data provide new insights into norovirus evolutionary dynamics and indicate new putative epitope "hot-spots" of modified and optimized norovirus-host interactions.

Keywords

norovirus;molecular evolution;chronic infection;solid organ transplantation;HBGA binding;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL MF - Faculty of Medicine
UDC: 578
COBISS: 33668057 Link will open in a new window
ISSN: 1664-302X
Views: 419
Downloads: 77
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Other data

Secondary language: Slovenian
Secondary keywords: norovirus;molekularna evolucija;kronična okužba;presaditev organov;vezava HBGA;
Type (COBISS): Article
Pages: str. 1-12
Issue: ǂVol. ǂ9
Chronology: Mar. 2018
DOI: 10.3389/fmicb.2018.00371
ID: 13177520