In baculovirus, a large double stranded enveloped DNA virus, so far only a single protein, named GP41, has been identified as an O-glycosylated tegument protein. Baculoviruses are specific for insects and have been widely used as biocontrol agents of insect pests, as well as efficient gene expression and gene delivery vectors for human therapy.

GP41 was originally identified as an O-linked glycoprotein and most likely to occupy the space between the nucleocapsid and the envelope of the ODV, i.e. within the tegument. Whether GP41 is associated with BVs, however, remains controversial. 

In a recent study, the research group led by Prof. WANG Hualin in Wuhan Institute of Virology of the Chinese Academy of Sciences pointed out a close correlation between GP41 oligomerization and its function. They highlighted the oligomeric state as the functional form of GP41 in baculovrius replication cycle. 

In this study, for the first time, the gp41 gene of AcMNPV was knocked-out by using the λ-Red homologous recombination method, and its function during the virus replication cycle was comprehensively investigated.

GP41 was found to be not only essential for nucleocapsid egress from the nucleus to produce BV, but was also indispensable for ODV morphogenesis, therefore the nature of GP41 was further investigated.  

When GP41 was found as dimers and trimers in infected cells and as trimers in both BVs and ODVs, the scientists set out to investigate whether or not disulfide bridging and protein-protein interactions were involved in the oligomerization of GP41 and what the consequences of specific mutations in GP41 to prevent oligomerization would be on the morphogenesis and assembly of BV and ODV. 

The results have been published in Journal of Virology entitled "The functional oligomeric state of tegument protein GP41 is essential for baculovirus BV and ODV assembly". 

This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China, the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences, the Virology Key Frontier Science Program of State Key Laboratory of Virology and a grant to JMV from State Key Laboratory of Virology And Wuhan Institute of Virology.  

Proposed model for GP41 transportation, oligomerization, and function in the AcMNPV life cycle. (Image by WANG Hualin)