Hemoglobin subunit beta interacts with the capsid, RdRp and VPg proteins, and antagonizes the replication of rabbit hemorrhagic disease virus.

Rabbit hemorrhagic disease virus (RHDV) causes a highly contagious disease in rabbits that is associated with high mortality. Because of the lack of a suitable cell culture system for RHDV, its pathogenic mechanism and replication remain unclear. This study found that the expression level of host protein rabbit hemoglobin subunit beta (HBB) was significantly downregulated in RHDV-infected cells. To investigate the role of HBB in RHDV replication, small interfering RNAs for HBB and HBB eukaryotic expression plasmids were used to change the expression level of HBB in RK-13 cells and the results showed that the RHDV replication level was negatively correlated with the expression level of HBB. It was also verified that HBB inhibited RHDV replication using constructed HBB stable overexpression cell lines and HBB knockout cell lines. The interaction of HBB with viral capsid protein VP60, replicase RdRp, and VPg protein was confirmed, as was the activation of the expression of interferon γ by HBB. The results of this study indicated that HBB may be an important host protein in host resistance to RHDV infection.