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Construction and properties of a recombinant pseudorabies virus with tetracycline-regulated control of immediate-early gene expression

Muñoz, A.L., Gadea, I., Lerma, L., Varela, L., Torres, M., Martín, B., García-Culebras, A., Lim, F., Tabarés, E.
Journal of virological methods 2011 v.171 no.1 pp. 253-259
Suid herpesvirus 1, doxycycline, gene expression, genes, lethal dose 50, mice, mutants, virulence, virus replication, viruses
A study was carried out to determine whether altering the control of expression of the IE180 gene of pseudorabies virus (PRV), by replacing the IE180 promoter with the tetracycline-responsive promoter (Ptet), affects virus replication and virulence. This PRV-BT90 mutant virus was constructed by complementation and recombination in Hela Tet-Off cells. The virus yield produced by infection of Hela Tet-Off cells with PRV-BT90 was similar to that of the parental virus vBecker2. Viral replication of PRV-BT90 was reduced in Vero cells as reflected by a reduction of virus yield and plating efficiency compared to vBecker2. PRV-BT90 plaque formation in Hela Tet-Off cells was inhibited in the presence of doxycycline, whereas vBecker2 plaque formation was not affected. Subcutaneous infection of mice with the two viruses revealed a LD₅₀ higher than 10⁶ TCID₅₀ for the PRV-BT90 mutant virus while the LD₅₀ was 178 TCID₅₀ for the vBecker2 parental virus.