冠狀病毒Poly(A) Tail長度的調節並不具有宿主細胞的專一性

Abstract

The coronavirus genome is a single-stranded, (+)-sense RNA molecule of ~30 kilobases in length. As with a majority of eukaryotic messenger RNAs, the coronavirus genome contains a 5’ cap, 5’ and 3’ untranslated regions of ~200 and ~300 nucleotides, respectively, and a poly(A) tail of >100 nt. We have found that the length of the poly(A) tail in the bovine coronavirus (BCoV), a group β coronavirus, is regulated throughout infection in human rectal tumor (HRT) cells and baby hamster kidney cell line BHK-21. To determine whether regulation of viral poly(A) tail length is a common feature of coronaviruses, and whether it is host-specific, poly(A) tail length of wild-type avian infectious bronchitis virus, strain TW1 (wt IBV-TW1) , a group γ coronavirus, was studied in the primary chicken embryo kidney(CEK) cells and 4-day-old SPF chickens. By ligating head-to-tail pyrophosphatase-treated viral RNA (+) strands and sequencing across the junction, the poly(A) tail length of wt IBV-TW1 was found to vary in CEK cells and in the trachea of the SPF chickens throughout infection, suggesting that regulation of poly(A) tail length is a common coronavirus phenomenon. Poly(A) tail length variation was similarly found with the IBV vaccine strain H-120 in CEK cells although the overall poly(A) tail length was shorter with this virus in comparison with the poly(A) tail length in IBV-TW1 virus. These results together suggest that the regulation of coronaviral poly(A) tail length during infection is a common feature among coronaviruses and is not host-specific. Furthermore, we speculate that the variation of poly(A) tail length may be an indicator of virulence based on the comparisons between wt IBV-TW1 (virulent) and IBV-H120 (avirulent).