Bovine coronavirus (BCoV) represents a significant etiological agent of enteric disease, exhibiting widespread endemicity and imposing substantial economic burdens on the livestock industry through its pronounced pathogenicity in neonatal calves. Within the betacoronavirus lineage A, several species including human coronaviruses (HKU1, OC43), equine coronavirus (ECoV), murine hepatitis virus (MHV), canine respiratory coronavirus (CRCoV), and porcine hemagglutinating encephalomyelitis virus (PHEV) demonstrate phylogenetic relatedness to BCoV. As an enveloped RNA virus with a positive-sense, single-stranded genome, BCoV expresses the hemagglutinin–esterase (HE) glycoprotein, which functions as an auxiliary receptor-binding protein and potentially influences viral evolution through modifications in host range determination and tissue tropism.

This investigation analyzed fecal specimens (n=188) obtained from diarrheic calves to assess HE gene variability. Total RNA was extracted following standardized protocols, and HE-specific amplification was performed using targeted primers yielding 497-bp amplicons. Electrophoretic visualization confirmed successful amplification, with molecular detection revealing BCoV prevalence of 15.42% (29/188 samples). Bidirectional Sanger sequencing was conducted on selected positive isolates, and comparative sequence analysis was performed using BLAST algorithms against established betacoronavirus databases. Molecular characterization identified distinct amino acid polymorphisms in isolates designated HE1, HE10, HE30, and HE40. Phylogenetic reconstruction demonstrated that isolates HE1, HE10, and HE40 exhibited monophyletic clustering, whereas isolate HE30 displayed divergent evolutionary positioning, clustering proximally with SARS-CoV-2 variants of Chinese, Israeli, and American origin.

Our investigation into the effects of the identified mutations in the HE gene is currently ongoing.