Objective   To investigate the effects of special deoxyribozyme DZ1133 targeting N gene of respiratory syncytial virus (RSV) on viral replication and airway inflammation in mice.    Methods   RSV infected BALB/c mice were nasally dripped with DZ1133

mutant DZ1133 and antisense oligonucleotide AS1133 respe-ctively. Pulmonary viral titers were detected by plaque forming experiment. Pulmonary RSV N mRNA expression was assayed by RT-PCR. Leukocytes and t

he subgroup cells in bronchoalveolar lavage fluid (BALF) were counted

and the concentration of cytokines such as TNF-α

IL-12

IFN-γ and IL-10 in BALF were assayed by ELISA. Pulmonary histopathology was performed to observe the inflammation of airway.     Results   Pulmonary titers of 0.2

0.4 and 0.8 mg DZ1133 treated mice were (2.75±0.21)×10

5

(1.86±0.20)×10

5

and (1.02±0.22)×10

5

PFU/g respectively

which were significantly decreased as compared with those of infected control mice [（7.94±0.42)×10

5

PFU/g

P0.01

]

. Meanwhile the pulmonary viral mRNA of 0.2

0.4 mg and 0.8 mg DZ1133 treated mice were inhibited by 30.51%

47.38% (P0.05) and 53.97% (P0.01) respectively compared with infected control mice. The inhibitory effects of DZ1133 on viral titer and mRNA expression were much stronger than AS1133. The treatment of 0.4 mg mutant DZ1133 had no significant inhibitory effect on RSV. In 0.4 mg DZ1133 treated group

total number of leukocytes in BALF was decreased dramatically and pulmonary histology was significantly improved compared with infected control (P0.05). But the treatment of 0.4 mg DZ1133 did not affect the productions of TNF-α

IL-12

IFN-γ and IL-10 in BALF of RSV infected mice (P0.05).    Conclusion   Special deoxyribozyme DZ1133 targeting RSV N gene effectively inhibits viral replication and reduces airway inflammation. DZ1133 is a potential therapeutic agent against RSV infection in vivo.