Novel astrovirus types circulating in Shandong Province (Eastern China) during 2016: A clinical and environmental surveillance

Abstract

Background: In recent years, several novel astroviruses have been discovered by molecular assays. Their prevalence in many parts of the world remains unclear.

Objectives: To investigate the existence and genetic diversity of novel astroviruses in China.

Study design: Stool specimens were collected from patients suffering gastroenteritis from two hospitals in Jinan city in 2016, and were screened for novel astroviruses by real-time RT-PCR assay. Positive samples were subject of ORF2-amplification by conventional RT-PCR and Sanger sequencing. In addition, 1 liter of sewage sample was collected monthly in 2016 and concentrated via the membrane adsorption/elution method. Partial ORF2 amplification, cloning and Sanger sequencing were conducted, and phylogenetic analysis was performed for genotyping all the obtained sequences.

Results: 18 of 635 specimens (2.8%) were positive for novel astrovirus detection by real-time RT-PCR assay and were further genotyped by Sanger sequencing as 13 MLB1, 4 MLB2, and 1 VA3. 100% (12/12) of sewage samples were positive for novel astroviruses by conventional RT-PCR. After cloning and sequencing, six known novel astroviruses (MLB1, MLB2, VA1, VA2, VA3, and VA5) were identified. VA2, MLB1, and VA1 were the most common subtypes being detected in 100.0% (12/12), 91.7% (11/12), and 91.7% (11/12) of the samples, respectively. Eighteen sequences that could not be classified into any known subtypes were found.

Conclusions: These results demonstrate the wide circulation and high diversity of novel astroviruses in Jinan, Shandong Province, China, and underline the significance of environmental surveillance combined with population-based surveillance for understanding the molecular epidemiology of enteric viruses.