Roles Of Matrix Metalloproteinases In Poxvirus Replication

The host range of poxvirus is very broad, including human, mammalian and insects. Poxvirus can affect skin tissue, cause febrile illnesses in human and animals with a prominent vesicular rash,even death, such as variola virus. The poxvirus infection can induce primary and adaptive immune responses, the symptoms associated with serious poxvirus infections are a result of a"cytokine storm"or sepsis and that this may be the underlying cause of pathology. As technical advances in engineering have resulted in the creation of numerous recombinant poxviruses for use as candidate vaccines, vectors for gene delivery, cancer immunotherapy and oncolytic agents in the treatment of cancer. Central to the rational design of these therapies is the need for detailed information about the immune interaction between poxvirus and hosts.MMPs play important roles in both physiological and pathological processes such as cancer metastasis and virus infection. The main MMPs involved in different virus replication and the modulation modes are different. Until now, the roles and expressiong of MMPs in poxvirus replication have not been reported. MMPs get involved in immune responses through breakdown of ECM, BM and modulate cytokine and chemokine to help immune cells arrive at inflammation sites through ECM. So, MMPs may play very important role in poxvirus replication.In this project, we studied on the procesure of vaccinia virus, myxoma virus and tanapox virus infection in their adaptive cells. The objectives of this study are determining the contribution of MMP activity to poxvirus virulence and the specific MMPs upregulated during poxvirus infection. This study can help us understand the mechanisms of poxvirus replication and find a new way for preventing poxvirus replication.1. Depression MMPs activity induce the suppressing of VV,MV and TPV replicationIn this study, a panel of eleven synthetic MMP inhibitors was tested the inhibitory effects on VV,MV and TPV replications. The effects of MMPs inhibitors on cell viability at their working concentrations were tested by standard tetrazole reduction (MTT) assay.The results showed, MMPs inhibitors have general inhibition effects on poxvirus infection. All three viruses'replications were suppressed remarkably by CHX in a dose-dependent manner. MTT results showed that there was no any visible cytotoxic effect on cell survival by any of the concentrations of inhibitors in all treatment groups compare to untreated cells. According to the substrates of MMPs inhibiors, the main MMPs involved in poxvirus infection may be MMP-2 or MMP-9.VV,MV and TPV replication can be suppressed by MMPs inhibitors in the absence of inhibitor-associated cytotoxicity. So, depression MMPs activity induce the suppressing of VV,MV and TPV replication, MMPs activity may play an important role in VV,MV and TPV replication.According to the substrates of MMPs inhibiors, the main MMPs involved in poxvirus infection may be MMP-2 or MMP-9.2. MMP activity is a main factor of VV,MV and TPV replicationThe MMP activity following poxvirus replication was evaluated by analyzing the activity in the serum free culture medium of cells using a colorimetric substrate cleavage assay. XG076 was applied to blockade of zymogen processing and test the influence of this procedure on poxvirus replication. The inhibition of zymogen activity by XG076 did not significantly alter poxvirus infection comparing with the untreated groups (XG076 untreated).MMP activity is a main factor of VV,MV and TPV replication. And, MMPs may exert biological effects in manners that are independent of their enzyme activation pathway.3. VV and MV infection are associated with imbalance of MMP-9, MMP-2, TIMP-1 and TIMP-2Real time PCR was applied to evaluate the mRNA levels of MMPs and TIMPs. Gelatin zymogaphy was applied to evaluate the protein levels of MMP-2 and MMP-9.The mRNA and protein levels of MMP-2 and MMP-9 were up regulated after VV and MV infection. At the same time, the mRNA levels of TIMP-1 and TIMP-2 were down regulated.Thus, VV and MV infection are associated with imbalance of MMP-9, MMP-2, TIMP-1 and TIMP-2.In summary, the MMP activity is a main factor of VV,MV and TPV replication. And, the expression of MMP-9 and -2 were up regulated at mRNA and protein levels, in contrast, the mRNA levels of TIMP-1 and -2 were down regulated. Poxvirus infection is associated with imbalance MMP-9, MMP-2, TIMP-1 and TIMP-2. The results suggest that MMPs, especially MMP-9 and MMP-2, may be a target molecule in the strategy of treatment of poxvirus replication and related diseases. This study can help us find a new way to prevent poxvirus infection, understand the mechanisms of poxvirus replication in order to apply poxvirus in gene enginerring and cancer immunotherapy and virotherapy.