Characterization of an attenuated TE3L-deficient vaccinia virus Tian Tan strain

An attenuated vaccinia virus (VACV), TE3L(-)VTT, was evaluated for virulence and safety to determine its potential use as a vaccine or as a recombinant virus vector to express foreign genes. The virulence of TE3L(-)VTT was compared with that of the wild-type VTT both in vivo and in vitro. The humoral and cellular immune responses were detected in a mouse model to test the vaccine efficacy of the TE3L mutant. The results suggested that deletion of the TE3L gene decreased the virulence and neurovirulence significantly in mice and rabbit models, yet retained the immunogenicity. Thus, the deletion of TE3L improved the safety of the VTT vector; this approach may yield a valuable resource for studies of recombinant VACV-vectored vaccines.