Packaging of Rift Valley fever virus pseudoviruses and establishment of a neutralization assay method

Li, Yuetao; Zhao, Yongkun; Wang, Cuiling; Zheng, Xuexing; Wang, Hualei; Gai, Weiwei; Jin, Hongli; Yan, Feihu; Qiu, Boning; Gao, Yuwei; Li, Nan; Yang, Songtao; Xia, Xianzhu

Certain viruses, such as the severe acute respiratory syndrome-associated coronavirus (SARS-CoV), Ebola virus (EBOV), and H5N1 subtype avian influenza virus, are highly infectious and highly pathogenic, presenting tremendous difficulties and dangers during research [8, 13, 19] . In contrast, pseudovirus technology is a very safe and effective research tool [18] . Briefly, a pseudovirus is a type of retrovirus that can integrate with the envelope glycoprotein of another type of virus to form a new virus with an exogenous viral envelope and a genome that maintains the characteristics of the retroviral genome. Compared with natural viruses, pseudoviruses integrate with the envelope protein of another virus by using an envelope protein-encoding gene within a modified nucleic acid molecule; pseudoviruses can only accomplish one infection cycle because they lose their self-replicating ability. Thus, pseudoviruses are more biologically safe than infectious viruses. Pseudoviruses also have extensive host ranges and higher transfection efficiencies, can be more easily concentrated than the original viruses, can defend against the deactivation function of serum complement, have a non-cell-cycle-dependent integration feature, and can efficiently transfect quiescent cells. Pseudovirus preparation is thus an effective, safe, and reliable method for application in the study of viruses with high pathogenicity that are difficult to culture in vitro. Because pseudoviruses are relatively safe and have the advantages of extensive host range, non-cell-cycle-dependence, and highly efficient transfection of quiescent cells, they can have particularly important roles in studies of virus-host cell interactions, neutralizing antibody titer evaluation, and gene therapy. Thus, pseudoviruses can be used as a novel, safe experimental tool.