Quantitative and molecular analysis of noroviruses RNA in blood from children hospitalized for acute gastroenteritis in Belém, Brazil

Abstract

Background: Noroviruses (NoVs) are a common cause of acute gastroenteritis (AGE) and until now, little is known about its ability to spread outside the gut.

Objectives: We aim to investigate the role of NoVs causing viremia in children hospitalized for AGE, as well as to correlate the presence of NoVs RNA in serum with clinical severity and stool viral load.

Study design: Paired stool and serum samples were collected from 85 pediatric patients under 6 years hospitalized for AGE from March to September 2012 in Belém, Brazil. Enzyme-linked immunosorbent assay (EIA) and reverse transcription quantitative PCR (RT-qPCR) were used to detect and quantify NoVs, respectively. Phylogenetic analysis of the partial ORF2 region was used to genotype the strains detected.

Results: NoVs were detected in 34.1% (29/85) of stool samples. By qRT-PCR, we found a high rate of NoVs' RNA in serum samples (34.5%) among NoVs-positive AGE cases, and was associated with a longer hospitalization (6.5 vs. 4.0 days; p=0.006), as well as with a higher stool viral load (3.9×10(11) vs. 1.1×10(11) GC/g; p=0.0472). NoVs strains were classified as GII.4 (90% of genotyped strains) and GII.7 (10%). The same genotype was found in paired stool and serum samples.

Conclusion: Detection and molecular characterization of NoVs GII in paired stool and serum samples suggest that the dissemination of NoVs to the blood stream is not uncommon, but the role of viruses spread outside the gut and the relationship with disease severity need to be further addressed.

Keywords: AGE; EIA; NoVs; Noroviruses; RT-qPCR; Serum samples; Viral load; Viremia; acute gastroenteritis; enzyme-linked immunosorbent assay; noroviruses; nt; nucleotide; reverse transcription quantitative PCR.