The Important Role of Lipid Raft-Mediated Attachment in the Infection of Cultured Cells by Coronavirus Infectious Bronchitis Virus Beaudette Strain

Guo, Huichen; Huang, Mei; Yuan, Quan; Wei, Yanquan; Gao, Yuan; Mao, Lejiao; Gu, Lingjun; Tan, Yong Wah; Zhong, Yanxin; Liu, Dingxiang; Sun, Shiqi

Avian infectious bronchitis virus (IBV) is a member of the Coronaviridae family, which includes many human and animal pathogens of global concern, such as severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome virus (MERS-CoV), and mouse hepatitis virus(MHV) [1] . IBV has a major economic impact on the global poultry industry because this prototype coronavirus considerably decreases hen egg production by impairing the upper respiratory and reproductive tracts of chickens [2] . IBV is an enveloped positive-stranded RNA virus with a 27-30 kb genome that encodes several polyproteins. The polyproteins of IBV a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 are cleaved by viral proteases into at least 15 nonstructural proteins (NSPs) [3] . Four structural proteins, namely, spike protein (S), nucleocapsid protein (N), membrane protein (M), and small envelope protein (E), are encoded by subgenomic RNA species [4] . The binding and entry of IBV into host cells require interactions between cellular surface receptors and viral structural proteins that are involved in the attachment stage. Nearly all IBV field isolates can only be propagated in embryonated chicken eggs or transiently proliferated in primary chicken embryo kidney cells. However, the Beaudette strain, a cell-adapted strain, replicates efficiently in various cultured mammalian cell lines, including African green monkey kidney cells (Vero), human liver cancer cells, lung cancer cell lines, and baby hamster kidney cells through serial passages [5] [6] [7] [8] . However, the detailed mechanism underlying virus-host interactions during viral attachment and entry remains uninvestigated. Here, we used the Beaudette strain as an in vitro model to study the mechanism of IBV infection.