Regulation of coronaviral poly(A) tail length during infection is not coronavirus species- or host cell-specific

It has been demonstrated that the length of the poly(A) tail in the bovine coronavirus (BCoV), which belongs to genus betacoronaviruses, is regulated throughout infection in human rectal tumor-18 (HRT-18) cells, and the length of the poly(A) tail is associated with the efficiency of virus translation. Here, we examined whether the regulation of viral poly(A) tail length is cell-type independent and whether it is a common feature of coronaviruses to assess the significance of the regulation. By ligating head-to-tail viral RNA positive strands and sequencing, we found that (1) the regulation pattern of coronaviral poly(A) tail length in BCoV-infected hamster kidney-21 (BHK-21) cells was similar to that in BCoV-infected HRT-18 cells and (2) the poly(A) tail length of wild-type avian infectious bronchitis virus (IBV) virulent strain IBV-TW1, which is in the genus gammacoronaviruses, varied throughout infection in primary chicken embryo kidney (CEK) cells and in the tracheas of 1-day-old chicks. Interestingly, the poly(A) tail length variation was similarly found in the avirulent IBV strain H120 in CEK cells, although the overall poly(A) tail length was shorter for this virus. The results suggest that the regulation of coronaviral poly(A) tail length during infection may be a common feature among coronaviruses and can occur in a noncancerous cell line (BHK-21 cells), primary cell culture (CEK cells), and living system (chickens), further reinforcing the biological significance of this regulation during coronavirus infection.