Formation of virus-like particles from cloned cDNAs of Thogoto virus

This study investigated whether virus-like particles (VLPs) of Thogoto virus (THOV) can be generated entirely from cloned cDNAs and whether these particles are functionally competent. Using a plasmid-based reverse genetics system, the authors co-expressed all six structural proteins of THOV (PB1, PB2, PA, NP, GP, and M) along with a minireplicon encoding a reporter gene flanked by viral promoter sequences. The viral polymerase complex and NP successfully reconstituted functional ribonucleoprotein complexes capable of replicating and transcribing the minireplicon RNA. Upon inclusion of GP and M, these artificial nucleocapsids were efficiently packaged into VLPs and released into the supernatant. The VLPs were able to transfer the minireplicon into indicator cells, although detectable reporter expression required prior infection with helper virus, indicating limited intrinsic polymerase activity. Importantly, all six structural proteins were necessary for the formation of infectious VLPs, as omission of either GP or M abolished particle infectivity. Neutralization assays confirmed that the VLPs structurally resembled authentic virions. Overall, this study establishes a functional THOV VLP system and provides a foundation for full virus rescue and detailed analysis of viral replication and assembly mechanisms.
(TMR)