A reassortant G3P[12] rotavirus A strain associated with severe enteritis in donkeys (Equus asinus)

Abstract

Background: In contrast to horses, the only evidence suggesting gastrointestinal disease in neonatal donkeys is associated with Group A rotaviruses (RVAs) is the detection of viral antigens by ELISA in just 1 of 82 symptomatic donkey foals. No additional, more comprehensive investigations have been conducted, and RVAs if circulating in donkey populations have not been molecularly characterised.

Objectives: To investigate if RVAs are associated with an outbreak of severe enteritis in neonatal donkeys and if associated determine the genotype(s) along with the phylogenetic relationship to RVA strains circulating in horses.

Study design: Cross-sectional.

Methods: RT-PCR-based techniques were used for RVA diagnosis and gene amplification. Statistical significance was determined by Chi-square and Fisher's exact two-sided tests. Genotyping was performed by RotaC and phylogenetic analysis by neighbour joining.

Results: In 2019, acute enteritis occurred in 119 of 206 donkey foals (≤4 months) at two intensive donkey farms in the Shandong province of China. The highest morbidity (68.1%), mortality (29.5%) and fatality levels (45.5%) occurred in foals in the 30-89 day, 30-59 day and 0-29 day age groups respectively. RVA gene sequences were detected in 107 (89.9%) of the symptomatic individuals while further analysis demonstrated the outbreak was associated with the same G3P[12] RVA strain designated RVA/Donkey-wt/CHN/Don01/2019/G3P[12]. Although the VP4 gene of Don01 exhibited close phylogenetic relationships with equivalent RVA sequences commonly circulating in horses, encoding VP7 was more closely associated with sequences isolated from bats suggesting this new donkey strain arose via an intergenogroup reassortment event.

Main limitations: Actual prevalence not determined because <7% of asymptomatic donkey foals were included in this study. The complete genomic sequence of RVA/Donkey-wt/CHN/Don01/2019/G3P[12] remains to be determined.

Conclusions: Valuable new information about the molecular epidemiology of rotaviruses in different equid species is provided by isolation and molecular characterisation of a novel RVA strain from neonatal donkeys.

Keywords: G3P[12]; VP4; VP7; donkey; rotavirus; severe enteritis.