Severe diarrhea outbreak in beef calves (Bos indicus) caused by G6P[11], an emergent genotype of bovine rotavirus group A

Abstract

The episodes of diarrhea caused by neonatal bovine rotavirus group A (BoRVA) constitute one of the major health problems in the calf rearing worldwide. The main G (VP7) and P (VP4) genotypes of BoRVA strains involved in the etiology of diarrhea in calves are G6P[1], G10P[11], G6P[5], and G8P[1]. However, less frequently, other G and P genotypes have been described in BoRVA strains identified in diarrheic fecal samples of calves. This study describes the identification and molecular characterization of an emerging genotype (G6P[11]) in BoRVA strains involved in the etiology of a diarrhea outbreak in beef calves in a cattle herd of high production in extensive management system. The diarrhea outbreak, which showed high morbidity (60%) and lethality (7%) rates, occurred in calves (n= 384) Nelore (Bos indicus) up to 30-day-old from the State of Mato Grosso do Sul, Brazil. BoRVA was identified in 80% (16/20) of the fecal samples analyzed by polyacrylamide gel electrophoresis (PAGE) technique. In all PAGE-positive fecal samples were amplified products with 1,062-bp and 876-bp in the RT-PCR assays for VP7 (G type) and VP4 (VP8*) (P type) of BoRVA, respectively. The nucleotide sequence analysis of VP7 and VP4 genes of four wild-type BoRVA strains showed G6-III P[11]-III genotype/lineage. The G6P[11] genotype has been described in RVA strains of human and animal hosts, however, in calves this genotype was only identified in some cross-sectional studies and not as a single cause of diarrhea outbreaks in calves with high morbidity and lethality rates as described in this study. The monitoring of the G and P genotypes of BoRVA strains involved in diarrhea outbreaks in calves is important for both animal and public health by allowing the identification of the most frequent genotypes, the characterization of novel genotypes and to identify reassortments with genotypes described in animal and human hosts. The results of this study show the importance of the monitoring of the genotypes of BoRVA strains involved in episodes of bovine neonatal diarrhea as for characterization of frequency of occurrence and pathogenic potential of uncommon genotypes as for monitoring of the emergency of different BoRVA genotypes not included in commercial vaccines.

Longitudinal study of bovine rotavirus group A in newborn calves from vaccinated and unvaccinated dairy herds

“…Alkan et al (2010) reported that the G6P[11] lineage found in Turkey formed a unique G6 lineage with only 90.1% amino acid identity to the G6 strain NCDV found in the vaccines. Medeiros et al (2014a) also reported an outbreak of diarrhea in beef calves in Brazil caused by a G6P[11] distant from the most common lineages of RVA strains G6P[1] and G6P [5]. As the strain found in the vaccinated herd of the present study showed a nucleotide sequence identity of 91.2% to the Fig.…”

“…The strain found in the vaccinated herd (G6P[11]) was different from the strain of the non-vaccinated herd (G6P[5]), and none of these strains were present in the commercial vaccines available by the time of the experiment. In Brazil, G6P [11] has been incriminated as a cause of a diarrhea outbreak in a beef herd (Medeiros et al 2014a), although there are also reports of its occurrence as the most common genotypic combination in some states of country (Silva et al 2012). In Ireland, G6P[11] is reported as a low prevalence genotypic combination found especially in dairy herds (Collins et al 2014), while in Turkey, Alkan et al (2010) reported a high prevalence of this genotype in either unvaccinated herds and in herds immunized against G6P [1].…”

Rotavirus A in wild and domestic animals from areas with environmental degradation in the Brazilian Amazon

“…Although the results of RVA have already been described globally [12,[23][24][25][26][27][28][29][30], in Brazil, the occurrence, diversity and role of rotavirus in these animals are still poorly studied, considering the large number of present species [4,[31][32][33][34].…”

Outbreak of neonatal diarrhea caused by multiple genotypes of rotavirus A in a beef calves herd

“…In Brazil, epidemiological studies conducted to date have shown that, in calves, bovine rotavirus A (BoRVA) is the virus most commonly associated with neonatal diarrhea (Alfieri et al 2004, Silva et al 2012, Medeiros et al 2014. Rotaviruses belong to the Reoviridae family and have a triple-layered icosahedral protein capsid.…”

“…Among the P genotypes, P[1], P[5] and P [11] are found in RVA strains of bovine origin. The G and P genotype combinations most commonly found in bovine RVA strains are G6P (Alfieri et al 2004, Caruzo et al 2010, Martella et al 2010, Freitas et al 2011, Badaracco et al 2012, Papp et al 2013, Collins et al 2014, Medeiros et al 2014. RVs cause malabsorption and toxin-mediated secretory diarrhea, especially in calves less than 3 weeks old (Foster & Smith 2009).…”