Serologic and genotypic studies of the spike glycoprotein of turkey coronavirus
Boynton, Tye O'hara
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The serologic and genotypic relationship of different turkey coronavirus isolates (TCoV) was studied. Recent analysis of available sequence data suggest the presence a hypervariable region (HVR) within the S1 subunit of the spike gene in TCoV. The effect of this region on serotype is unknown. We examined the mutation rate of the putative HVR by studying its sequence from serial passages of each isolate in SPF embryonating turkey eggs. Mutations in one strain were found to be localized to this region and another region upstream, rather than randomly placed throughout the 906 bp sequence. To study the serologic relationships, a novel means of virus neutralization was also developed. Antisera was raised against different TCoV isolates and used in homologous and heterologous neutralization reactions. Neutralization was determined by presence of virus quantified by real-time RT-PCR. Results indicate that a serological difference exists between strains, suggesting that serotypes exist within TCoV isolates.