Bovine astrovirus (BoAstV) is associated with gastroenterical disorders such as diarrhea, particularly in neonates and immunocompromised animals. Its prevalence is >60 % in the first five weeks of the animal's life. The aim of this study was to detect and perform a phylogenetic analysis of BoAstV in Brazilian cattle. A prevalence of 14.3 % of BoAstV in fecal samples from 272 head of cattle from different Brazilian states was detected, and 11 samples were analyzed by nucleotide sequencing. The majority of positive samples were obtained from diarrheic animals (p < 0.01). Phylogenetic analysis revealed that Brazilian samples were grouped in clades along with other BoAstV isolates. There was 74.3 %-96.5 % amino acid sequence similarity between the samples in this study and >74.8 % when compared with reference samples for enteric BoAstV. Our results indicate, for the first time, the occurrence of BoAstV circulation in cattle from different regions of Brazil, prevalently in diarrheic calves.

It is suggested that Bovine kobuvirus (BKV) is involved in the etiology of gastroenteric diseases especially among calves; however, this association remains unknown. This study evaluated 216 fecal samples from cattle with and without diarrhea symptoms obtained from different regions of Brazil. A 216 bp fragment of the BKV 3D gene was amplified by RT-PCR in 14.4 % (31/216) of the studied samples, and 17 samples were subjected to nucleotide sequencing. All positive samples were obtained from animals aged less than 5 months, and most of animals presented diarrhea (p < 0.05). Phylogenetic analyses showed that the obtained sequences were grouped within the genogroup 2 of BKV forming subclades specific for each Brazilian municipality sampled. In addition, the alignment of the sequences revealed differences of nucleotides between sequences from different locations. Our results indicate for the first time that there is a regional genotypic differentiation of BKV in Brazil.

Nebovirus is a new genus of viruses belonging to the Caliciviridae family recently characterized in cattle, and is associated with gastrointestinal disorders, such as diarrhoea, anorexia and intestinal lesions particularly in calves. The aim of this study was to investigate the prevalence of neboviruses in Brazilian cattle and analyse phylogenetically the virus strains detected. A prevalence of 4·8% of neboviruses in faecal samples from 62 head of cattle from different Brazilian states was detected. All positive animals were aged 96·0% nt (100% aa) sequence identity between the virus sequences in this study and >88·8% nt (>94·4% aa) identity with Newbury1/UK. Our results indicate, for the first time, the occurrence of neboviruses in Brazil as well as in South America, and the first Newbury1-like nebovirus found outside the UK.

Picobirnaviruses (PBVs) are emerging and opportunistic viruses with possible zoonotic potential. In this study, we present the detection, molecular characterization, and genotypic differentiation of PBVs from genogroup I in bovine stool samples from different Brazilian regions. A high proportion of PCR-positive samples (23.4%) was detected in a total of 77 analyzed. Nucleotide identity, alignment, and phylogenetic analyses revealed high diversity among the studied sequences. The results obtained indicate, for the first time, the circulation of bovine PBVs belonging to genogroup I in different Brazilian states, with heterogeneous phylogenetic-clustering profiles.

The Infectious Bursal Disease Virus (IBDV) causes immunosuppression in young chickens. Advances in molecular virology and vaccines for IBDV have been achieved by viral reverse genetics (VRG). VRG for IBDV has undergone changes over time, however all strategies used to generate particles of IBDV involves multiple rounds of amplification and need of in vitro ligation and restriction sites. The aim of this research was to build the world’s first VRG for IBDV by yeast-based homologous recombination; a more efficient, robust and simple process than cloning by in vitro ligation. The wild type IBDV (Wt-IBDV-Br) was isolated in Brazil and had its genome cloned in pJG-CMV-HDR vector by yeast-based homologous recombination. The clones were transfected into chicken embryo fibroblasts and the recovered virus (IC-IBDV-Br) showed genetic stability and similar phenotype to Wt-IBDV-Br, which were observed by nucleotide sequence, focus size/morphology and replication kinetics, respectively. Thus, IBDV reverse genetics by yeast-based homologous recombination provides tools to IBDV understanding and vaccines/viral vectors development.