Phylogeny of bovine norovirus in Egypt based on VP2 gene

The first complete genome sequence and genetic evolution analysis of bovine norovirus in Xinjiang, China

Introduction

Viruses are among the main pathogens causing diarrhoea in calves. The current study found that bovine norovirus (BNoV) is one of the principal viruses causing diarrhoea in calves in Xinjiang, China.

Material and Methods

A total of 974 calf faecal samples from six regions in Xinjiang were tested for BNoV using reverse-transcriptase PCR. The genomic characteristics of BNoV and the genetic evolution of the VP1 gene, protein three-dimensional structure characteristics and amino acid variation were analysed using bioinformatics methods.

Results

Epidemiological survey results showed that the infection rate of BNoV was 19.82%, and all samples tested positive in five regions. The results of the genetic evolution analysis showed that BNoV strains from Tacheng of northern Xinjiang and Kashgar of southern Xinjiang both belonged to the GIII.2 genotype of BNoV but were not on the same cluster of evolutionary branches. Additionally, the amino acid variation of the VP1 protein was not observed to significantly affect its spatial structure.

Conclusion

This study is the first to report the genetic characteristics of the BNoV complete genome sequence in Xinjiang and provides a scientific basis for BNoV vaccine development and pathogenesis research.

First Detection and Genomic Characterization of Bovine Norovirus from Yak

Yak are a unique free-grazing bovine species in high-altitude areas. The objective of this study was to investigate the presence and molecular characteristics of BNoV in yak. A total of 205 diarrheal samples of yak (aged ≤ 3 months) were collected from 10 farms in Sichuan Province, China, from May 2018 to October 2020, and four samples were detected as BNoV-positive with RT-PCR. Moreover, a nearly full-length genome of SMU-YAK-J1 containing three complete ORFs was successfully sequenced. Sequence analysis with only nine genome sequences of the GIII genogroup showed that SMU-YAK-J1 was most closely related with GIII.P2 GIII.4, sharing 90.9% gnomic nucleotide identity, but only shared 71.6–85.9% with other genotypes, which confirmed that SMU-YAK-J1 belongs to genotype GIII.P2 GIII.4. However, compared with the sole genome of GIII.4 in GenBank, the BNoV in this study also exhibited many unique amino acid changes among all the three ORFs, which may represent the unique genetic evolution of BNoV in yak. This study first determined the presence of BNoV in yak, contributing to a better understanding of the prevalence and genetic evolution of BNoV.

Evolutionary history and spatiotemporal dynamic of GIII norovirus: From emergence to classification in four genotypes

Noroviruses belong to a genetically diverse group of viruses infecting a wide range of mammalian host species, and those detected in cattle and sheep are classified within genogroup III (GIII). The current classification of norovirus in genogroups and genotypes is based on phylogenetic clustering and average distances within and between these phylogenetic clusters; however, the classification studies have been focused mainly on human norovirus, being GIII norovirus relegated. Due to the increasing number of studies on GIII norovirus, the need of an updated and extensive classification is evident. The aim of this study was to update the classification of norovirus within GIII, to describe the emergence of a circulating recombinant strain, and to reconstruct the evolutionary history of this genogroup. Two P-types (GIII.P1-2) and four genotypes (GIII.1-4) were described. For the genogroup GIII, the evolutionary rate estimated was 2.78E-3 s/s/y (95%HPD, 1.79E-3 s/s/y-3.78E-3 s/s/y), and the tMRCA was estimated around 1500 (95%HPD, 1247-1688). Despite the long history of this genogroup, the genotypes detected at present emerged in the last 100 years. Interestingly, most of the recombinant GIII.2P[1] strains detected worldwide were originated from a single recombination event and this recombinant strain was later dispersed through the world. Finally, our results indicate that a scenario of genotypes replacement through the time is highly probable.

Detection, risk factors and molecular diversity of norovirus GIII in cattle in Uruguay

Uruguay is a leading exporter of bovine meat and dairy products, and cattle production is one of the principal economic backbones in this country. A main clinical problem faced by livestock farmers is neonatal calf diarrhea (NCD); however, causes of NCD have not been extensively studied in Uruguay. Bovine norovirus (BoNoV) has been proposed as one of the possible etiologies of NCD as experimentally infected calves developed diarrhea and enteropathy, although limited information is available from field surveys. The aims of this study were to determine the frequency of infection, to investigate possible risk factors, and to determine the molecular diversity of BoNoV in Uruguay. A total of 761 samples of feces or intestinal contents from dairy and beef calves were analyzed through RT-qPCR. The overall frequency of detection of BoNoV was 66.1% with higher frequency in dairy (70.5%) than beef (15.9%) calves (p < 0.01). BoNoV was detected similarly in diarrheic (78.8%) and non-diarrheic (76.2%) dairy calves (p = 0.50). Calves ≤2 weeks of age (84%) were infected more often than older (62.7%) calves (p < 0.01). Phylogenetic analysis confirmed the presence of GIII.1 and GIII.2 genotypes. In addition, we reported the circulation of recombinant strains and the detection of a strain with the recently described novel VP1 genotype. This study represents the first report describing the circulation, the associated risk factors, and the molecular diversity of BoNoV in Uruguay.