Molecular characterization of bovine noroviruses and neboviruses in Turkey: detection of recombinant strains

Prevalence of Bovine Norovirus and Nebovirus and Risk Factors of Infection in Swedish Dairy Herds

Enteritis is the major cause of mortality in neonatal calves. Diagnostic work to detect the pathogens involved and identification of risk factors for such infections are imperative to improve calf health. Bovine norovirus (BNoV) and nebovirus prevalence was investigated using RT-PCR in 50 dairy herds in five geographic regions of Sweden. BNoV and nebovirus were found to be common infections in young dairy calves. BNoV was detected in 20% of 250 calves in 48% of the herds. Nebovirus was detected in 5% of the calves in 16% of the herds. Both infections were present in three herds (6%). BNoV-infected calves were younger (median age 7 days) than nebovirus-infected calves (median age 21 days). These infections were not detected in adult cows and young stock over 6 months of age tested in selected herds. Risk factors identified for BNoV infection were a high number of preweaned calves present at the time of sampling, colostrum uptake by suckling the dam only, calf kept in a single pen, and geographic location of herd, while no risk factors for nebovirus infection were identified in the multivariable analysis. Univariable analysis suggested risk factors for nebovirus infection to be geographic location and early separation from the dam.

Literature Review: Coinfection in Young Ruminant Livestock-Cryptosporidium spp. and Its Companions

The protozoan Cryptosporidium parvum is one of the major causative pathogens of diarrhoea in young ruminants; therefore, it causes economic losses and impairs animal welfare. Besides C. parvum, there are many other non-infectious and infectious factors, such as rotavirus, Escherichia coli, and Giardia duodenalis, which may lead to diarrhoeic disease in young livestock. Often, more than one infectious agent is detected in affected animals. Little is known about the interactions bet-ween simultaneously occurring pathogens and their potential effects on the course of disease. In this review, a brief overview about pathogens associated with diarrhoea in young ruminants is presented. Furthermore, information about coinfections involving Cryptosporidium is provided.

Viral Enteritis in Cattle: To Well Known Viruses and Beyond

Livestock products supply about 13 percent of energy and 28 percent of protein in diets consumed worldwide. Diarrhea is a leading cause of sickness and death of beef and dairy calves in their first month of life and also affecting adult cattle, resulting in large economic losses and a negative impact on animal welfare. Despite the usual multifactorial origin, viruses are generally involved, being among the most important causes of diarrhea. There are several viruses that have been confirmed as etiological agents (i.e., rotavirus and coronavirus), and some viruses that are not yet confirmed as etiological agents. This review summarizes the viruses that have been detected in the enteric tract of cattle and tries to deepen and gather knowledge about them.

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.

Genomic characterization of a nebovirus strain with a novel RdRp genotype in yaks

Neboviruses (NeVs) are important causative agents of calf diarrhea that belong to the family Caliciviridae. In this study, we investigated the genomic characteristics of a NeV strain from yaks that has a novel RdRp genotype. The complete genome of this strain (YAK/NRG-A9/19/CH) is 7454 nt in length and shares 68.3%-79.7% nt sequence identity with those of other NeVs. The RNA-dependent RNA polymerase (RdRp) gene of this strain shares 66.5%-78.5% nt sequence identity (74.0%-89.3% aa sequence identity) with the eight available complete NeV RdRp sequences, and a phylogenetic analysis based on these sequences showed that the new strain formed an independent branch, indicating that the RdRp of strain YAK/NRG-A9/19/CH may represent a novel RdRp genotype of NeV. These results contribute to a further understanding of the molecular characteristics and genetic evolution of NeVs.

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.