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

IBV is a prototype avian coronavirus that belongs to the genus Gamma-coronavirus. It is an enveloped, positive-strand RNA virus. Its envelope contains the major attachment spike protein (S), the membrane protein (M), and the minor envelope protein (E). The spikes are composed of S protein trimers, which are necessary for viral attachment and subsequent fusion of viral and cellular membranes. Therefore, the IBV S protein and other structural proteins likely interact with lipid rafts. These direct or indirect interactions can affect the infection cycle of the virus. To test this hypothesis, we performed several experiments to determine the function of lipid rafts in IBV infection. Our data showed that IBV structural proteins co-localized with lipid rafts in the plasma membrane and that IBV structural proteins remain localized with the GM1 protein. In addition, the drug-induced disruption of lipid rafts in Vero cells inhibited IBV infection, which likely occurred because lipid rafts are involved in viral attachment. These results indicated that lipid rafts in the cellular surface may mediate viral adhesion to facilitate IBV endocytosis.